CH428757A - Process for the preparation of p-nitrosophenyl ethers and their use for their conversion into N-substituted anilines - Google Patents

Description

The present invention relates to the preparation of p-nitrosophenyl ethers and to the use thereof for the manufacture of p-nitroso-N-substituted anilines. The invention relates in particular to the manufacture of p-nitroso-diphenyl-amine (p-nitroso-N-phenylaniline) which can then be reductively alkylated to form an N-isopropyl-N'-phenyl-p-phenylenediamine which is characterized by special antiozonant and antioxidant properties, and the manufacture of p-nitroso-N-methylaniline which is an important intermediate product in the production of vulcanizing agents for certain rubbers.

The p-nitroso-N-substituted anilines have special utility as chemical intermediates, particularly with regard to the case in which the nitroso-group can be reduced to give corresponding phenylenediamine derivatives. A preferred method for the preparation of these compounds would appear to be to directly aminate p-nitrosophenol and thereby provide a direct route from phenol as the starting material, but this route gives only useful results. very small yields, 3-5 /o. The present invention is based on the discovery that p-nitroso phenyl ethers can be made by direct etherification of p-nitrosophenol with an alcohol under mild conditions with a high yield of ether. The p-nitrosophenyl ethers so produced can then be aminated directly to form the corresponding p-nitroso-N-substituted anilines.

Not only are these etherification and amination phases both novel in themselves, but it will also be realized that the ethers produced by etherification represent valuable chemical intermediates for the manufacture of p-nitroso phenylamines at from p-nitrosophenol. In addition, etherification allows a direct route of amination from phenol because p-nitrosophenol can easily be made from the latter.

Other methods for the production of p-phenylenediamines are also more expensive, such as nitrosation and the subsequent rearrangement and reduction of the corresponding substituted aniline or the doubling of an aromatic amine diazotized at the para-d' position. an N-substituted aniline with subsequent reduction.

The present invention therefore provides a process for the manufacture of a substituted-p-nitroso-N-aniline, characterized by the reaction of p-nitrosophnol with a primary or secondary alcohol in the presence of an acid and at a temperature comprised in the range of The present invention also includes the subsequent reaction of the p-nitrosophenyl ether thus produced with an aliphatic or phenyl primary amine in the presence of an acid and at a temperature of 0-160°C.

Although p-nitrosophenyl ethers are known, there has previously been no method of obtaining them from readily available materials and by direct techniques. The known methods are indirect and give low overall yields. For example, the method generally employed involves a reduction of a p-nitrophenyl ether to the corresponding hydroxyl-amine which is then oxidized to the p-nitroso-phenyl ether. Product recovery usually requires the cumbersome operation of steam stripping under reduced pressure. This method is not interesting for an industrial development.

On the other hand, when one tries to etherify p-nitrosophenol directly with the usual etherifying reagents, one obtains mixtures of products in which the ether of the tautomeric oxime form of p-nitrosophenol is the predominant product.

In the present invention, following etherification, the unreacted solvent-reactant alcohol, which contains in solution both the product ether and unreacted p-nitro sophenol, can be replaced in a solvent exchange phase by a solvent having a sufficiently low solvent action for the p-nitrosophenol and a sufficiently high solvent action for the ether to cause precipitation of the p-nitrosophenol for repair and easy recovery of this p-nitrosophenol for recycling, but that it retains the ether produced in solution with it for receiving operation of this ether in a later phase.

If the alcoholic reactant is immiscible with water, and following the etherification, the acid constituents and the non-reacting p-nitrosophenol of the resulting etherification reaction mixture can be reacted with an aqueous alkaline agent in neutralization conditions to neutralize the acid and convert the unreacted p-nitrosophenol into the corresponding phenolate, the latter then being extracted into the aqueous phase thus obtained, followed by acidification of the said aqueous phase to convert the p-nitrosophenol phenolate which precipitates under these conditions to be separated and recycled, and where the ether produced is recovered in the form of a constituent of an organic phase, also formed during the neutralization, to be isolated or to be reacted subsequently, as we want.

Any primary or secondary alcohol can be used as alcoholic reagent. However, those more generally used and preferred do not contain more than about 30 carbon atoms. Examples of alcoholic reagents used in the practice of the invention are n-propyl alcohol, i-butyl alcohol, n-decyl alcohol, lauryl alcohol, tridecyl alcohol, stearyl alcohol, n-octacosanol, ceryl alcohol, cinnamic alcohol, tetrahydrofuryl alcohol, furfuryl alcohol, ethylene glycol, glycerol, penta-erythritol, p-octylbenzyl alcohol, p-methylbenzyl alcohol, p-chlorobenzyl alcohol, propargyl alcohol, isopropylpropargyl alcohol, 2-phenyl methanol, p-hexoxybenzyl alcohol, p-methoxybenzyl alcohol, p-nitrobenzyl alcohol and hexamethylene glycol. Other examples are the alcohol reagents listed below. The presently preferred alcoholic reagents in the practice of the invention are those characterized by the structural formula:

wherein each R is selected from hydrogen, an alkyl, alkenyl, alkynyl, phenyl, alkylphenyl, phenylalkyl, phenyl alcoholate, phenylalkenyl, alkyl alcoholate, hydroxyalkyl, cycloaliphatic, halophenyl, nitrophenyl, furan or tetrahydrofuran radical, but said alcohol not containing more than 30 carbon atoms.

The alcohol/p-nitrosophenol molar ratio is generally in the range of about 1:1 to 100:1, a preferred raw material often including 10-30% p-nitrosophenol, 70-90% alcohol and 0.25 to 10% acid, by mole.

The p-nitrosophenol-alcohol reaction is preferably carried out at a temperature comprised within the range of approximately 15 to 70°C. The reaction time is generally at least about 2 minutes and up to about 500 minutes, and under preferred temperature conditions is generally in the range of 10 to 200 minutes, and often 15 to 150 minutes. . Although the etherification generally takes place under conditions of temperature and time outside the ranges mentioned above, the yield of product under these conditions is generally lower than that economically feasible for industrial work, owing to side reactions. undesirable at higher temperature levels and as a result of excessively slow reaction rates at lower temperatures.

The choice of contact time naturally depends on the temperature employed. Since higher temperatures promote an increased rate of the etherification reaction and since various alcoholic reagents are used in the practice of the invention, it is important to match the time and temperature conditions in the limits of the above ranges to provide optimum performance.

The pressure conditions for etherification are not critical except that sufficient pressure is required to retain the reactants in the liquid phase. Pressures at least equal to the vapor pressure of the system are therefore employed.

Any acid can be used as a catalyst in carrying out the etherification, although stronger acids are preferred because they provide a higher rate of reaction. If an acid catalyst is not used, no reaction takes place, the reaction rate depending on the quantity of catalysts in the system, i.e. higher reaction rates are obtained with an increasing amount of catalyst. The acid catalyst/p-nitroso phenol molar ratio introduced into the etherification reaction is preferably no greater than about 1:1 and is generally in the range of about 0.005:1 to 0.2:1. With a catalyst content exceeding said 1:1 molar ratio, undesirable side reactions often occur with concomitant lowering of the ether yield. Usually with a given catalyst there is an optimum concentration which depends on the temperature and the particular ether being formed. For example, when sulfuric acid is employed as the catalyst, a concentration of about 2 mole percent (based on p-nitroso phenolic reactant) is advantageously used. Examples of catalyst acids are sulfuric, hydrochloric, phosphoric, p-toluenesulfonic, hydrobromic acids. hydriodic, iodic, perchloric, periodic, nitric, benzenesulfonic, methanesulfuric, orthophosphoric, pyrophosphoric, mono-, di- and tri-chloroacetic and maleic; phosphorus pentachloride, titanium titrachloride, aluminum chloride, boron trifluoride, ferric chloride, acid earths, for example silica-alumina, superfiltrol and acid ion exchange resins such as, for example, a polymerized sulfonated vinyl benzene. and others. Solid acid catalysts are particularly advantageously employed in the practice of the invention in the form of beds, for example in the form of columns or layers, in fixed catalyst bed type operations.

Although any acid catalyst can be used in the practice of the invention, the yields of ether obtained are often slightly lower when using carboxylic acid catalysts due to a tendency of the carboxylic acids to enter into secondary reactions. undesirable in the etherification reaction mixture. Certain high oxygen acids such as nitric acid, perchloric acid, periodic acid and others are also less desirable among inorganic acid catalysts due to the oxidative tendencies of these acids in the etherification reaction mixture. , accompanied by a reduction in the yield of ether produced.

The reaction rate and equilibration concentrations depend on the product of the concentration of the reactants.

Accordingly, the highest yield of ether is obtained under any given set of conditions when the alcoholic reactant serves as the sole solvent for the etherification reaction mixture and the p-nitrosophenol is maintained in the alcoholic solvent reactant at the level saturation, for example in the form of a paste, in which case the concentration range of the p-nitrosophenol is generally of the order of 0.2 to 3.5 molar, preferably 1 to 3 molar.

The etherification itself can advantageously be carried out using the alcoholic reagent as sole solvent of the reaction mixture for the reasons studied above. However, any suitable solvent chemically inert under the etherification conditions of the invention may be used in the etherification when reacting alcohols which are solid under the etherification conditions, and for complete the solvent action of a liquid alcoholic reagent.

The complementary solvent employed is preferably one in which the solubility of the unreacted p-nitroso phenol is only slight or practically zero, in order to facilitate the separation of the unreacted p-nitroso phenol for a reaction. later. The hydrocarbon solvents are advantageously employed as complementary solvents and are, when desired, conveniently exchanged, downstream of the etherification, for an alcoholic reagent in order to facilitate the precipitation and the removal of the p-nitrosophenol for recycling while preserving in solution the ether produced.

The equilibrium in the ether formation reaction can be shifted towards the ether side by fractional distillation under vacuum of the water of etherification of the reaction mixture. The alcohol reactant can also be partially distilled off by this technique as an alcohol-water azeotrope.

Although this increases the conversion per pass of p-nitrosophenol to ether from about 45-55% to about 60-65%, yet another improvement in the conversion per pass, up to about 95- 99 can be made by sparging a dry gas or dry vapor through the etherification reaction mixture. This improvement comes from the fact that. in the vacuum fractional distillation method, the water of etherification is returned as reflux. This tends to prolong the etherification reaction period to such an extent that undesirable side reactions occur, so that the distillation in practice can only be carried out for a period of time short enough to exclude side reactions, which which, in turn, lowers the degree of increase in conversion per pass obtainable without it.

When reference is made herein to sparging, it is meant the steps of passing a dry, i.e. substantially anhydrous, gas or vapor through the etherification reaction mixture for part or all of the formation of ether, and thereafter removing said vapor or gas from said reaction mixture under non-reflux conditions. The sprinkling agent emerging carries with it, in the form of entrainment or saturation steam, the etherification water generated during the etherification reaction. In all continuous flow type implementations, it is preferred to add the spray agent continuously as a separate stream and remove it from the reaction mixture at the same rate, as illustrated with reference to the drawing.

When this agent is an alcohol which is the same as the alcoholic etherification reagent, it can, in particular, in a discontinuous type operation, be included with the other etherification reagents and introduced with them into the reaction zone of etherification. In this case, the etherification reaction mixture thus obtained is maintained under the conditions of etherification temperature and pressure to cause the alcohol it contains to boil and thereby form alcohol bubbles. rising upwards to ensure sprinkling. Other liquid sprinkling agents can likewise be added with the filler to the etherification and vaporized for sprinkling.

Any suitable sparging agent may be used provided that it is in a gaseous state and is, except when it is the alcoholic etherification reagent, chemically inert when sparged through the etherification reaction mixture. .

Gases such as carbon dioxide, hydrogen, nitrogen, coal flue gases and the like can be employed as suitable sparging agents. Preferably, an alcohol, the same as that introduced into the etherification zone as an etherification reagent, is used as spraying agent, given that there are no separation problems involved with regard to the sprinkling agent and the alcoholic reagent. Most advantageously employed as sprinkling agents are those alcoholic reactants containing from 3 to 5 carbon atoms in the molecule. namely n-propanol, isopropanol, n-butanol, isobutanol, n-amyl alcohol, isoamyl alcohol and the corresponding unsaturated alcohols. These alcohols are preferred sparging agents because of their vapor pressure relationship with the water of etherification in the etherification reaction mixture, whereby the concentration of water in the vapor above the liquid during the sprinkling is greater than the concentration of water in the liquid, so it takes per volume of water removed. a proportionately smaller amount of sprinkling agent than when the water content of the vapor is less than that of the liquid. Of these preferred sprinkling alcohols the C1 and C5 n-butanol alcohols are preferred. The n-butanol is used particularly advantageously, since in this case the water content in the vapor is often of the order of ten times-and more-greater than that in the liquid, which is higher than that obtained when other products of the preferred Cg-Cg group are used. Other liquid spray agents can be employed alone or diluted with an inert gas such as nitrogen, carbon dioxide and the like to maintain the spray agent in a gaseous state. Diluting the spray agent introduces an additional constituent! into the reaction mixture, along with additional rectification problems, and are therefore dispensed with in the preferred practice of the invention. However, this practice is most advantageously employed when a high molecular weight alcoholic etherification reagent is to be used as the sparging agent and a diluent is required to maintain said alcoholic sparging agent in vapor form. In general, however, the pressure and temperature conditions of the etherification promote vaporization of the liquid spray agent and dilution is not necessary.

Examples of sprinkling agents, in addition to those mentioned above, which can be used in the practice of the invention are hydrocarbons such as benzene, toluene, n-hexane and cyclohexane; esters such as ethyl acetate, n-propyl acetate, n-butyl formate, n-butyl acetate, isobutyl formate and isobutyl acetate; chlorinated hydrocarbons such as chloroform, carbon tetrachloride and ethylene chloride; ketones such as diethyl ketone and methyl ethyl ketone; and ethers such as di-n-butyl ether, diethyl ether, di-n-propyl ether and the like.

In the preferred practice the sprinkling agent employed is saturated and characterized by a boiling point at 1 mm/Hg not exceeding about 700°C, since higher boiling products are, as well as some unsaturated, in many cases unstable to the point that they may undergo some decomposition with the introduction of impurities or undesirable side reactions which lead to purification problems and loss of yield.

The spray phase can be carried out under any temperature and pressure conditions suitable for etherification. Naturally, it is carried out most advantageously under conditions of temperature and pressure for the etherification which lead to the reduction to a minimum of the undesirable side reactions during this etherification and which, when a normally liquid sprinkling agent is used, are also suitable for maintaining said liquid spray agent in vapor form. Accordingly, in most cases the spray phase is conducted, when employing a normally liquid spray agent, at sub-atmospheric pressure. Thus, by way of example, when p-nitrosophenol is etherified with n-butanol at a temperature of approximately 550° C. for example, and n-butanol is used as spraying agent, the etherification reaction mixture is maintained during spraying at a pressure in the range of about 35-45 mm/Hg. If a different etherification temperature had been chosen, an appropriate pressure-probably sub-atmospheric-would have been chosen in accordance with which the vaporization of the n-butanol spray would have been ensured from one end of the tank to the other. 'aspersion. In general, therefore, when a normally liquid spraying agent is used, and depending on the specific etherification reagent, it is advantageous to carry out the spraying phase with a sub-atmospheric pressure, for example of the order of 15 to 30 mm/Hg.

When continuously introducing a normally liquid sparge into the etherification reaction zone, the rate of introduction will of course depend on the particular etherification reaction mixture. However, a rate of from about 1 to 20 moles, and more preferably from about 3 to 10 moles, of liquid spray agent per mole of p-nitrosophenol in the reaction mixture per hour may be employed in the most cases.

The sparge time to achieve substantially complete elimination of the etherification water does not exceed the time of the etherification reaction except in cases where the etherification equilibrium, before displacement, is reached in a short time. time, for example up to 20 minutes. The minimum spray time is generally around 20 minutes and the more commonly used spray time, although in some cases up to 500 minutes and more, is more often in the range of 30 minutes. at 50 minutes. Although longer spray times favor the occurrence of side reactions in the etherification reaction mixture, the time required will be even shorter than if fractional distillation under vacuum were employed.

Any aliphatic or phenyl primary amine can be used as aminating agent, its choice being generally determined by the final product sought. Aniline is a preferred amination reagent now not only because of its reactivity and stability under amination conditions, but also because it leads to the formation of diphenyl amine derivatives which have many applications as well. known in the art. Examples of amine reactants are: ethylamine, isopropylamine, isobutylamine, allylamine, laurylamine, beta-phenylethylamine, tetrahydroabietylamine, deshydroabiethylamine, hexamethylenediamine, p-aminodiphenylamine and 2-amino-2-methyl-1-propanol.

Other examples of amines as reagents are given in Table 1 below.

Primary amines preferred as reagents in the practice of the present invention are those represented by the structural formula RNH: 2 wherein R is a radical selected from the group consisting of: alkyl, alkenyl, phenyl, halophenyl, amino phenyl, phenylalkyl , abietylalkyl, cycloaliphatic, hydroxyalkyl, alkylphenyl, alkoxyphenyl, aminotolylphenyl, hydroxyphenyl, aminobiphenyl and phenyl aminophenyl, but said amine containing not more than 30 carbon atoms in the molecule.

Any p-nitrosophenyl ether produced by the first stage of etherification can be used for the amination, but it is preferable that it does not contain more than 36 carbon atoms. Examples of such ethers are octacosanol p-nitrosophenyl ether, mono-p-nitrosophenyl ether of ethylene glycol. glycerol mono-p-nitrosophenyl ether, penta-erythritol mono-p-nitrosophenyl ether, hexamethylene glycol mono-p-nitrosophenyl ether, p-nitrosophenylhexoxybenzyl ether, n- nitrosophenyl-n-propyl, p-nitrosophenyl-i-butyl ether, p-nitrosophenyl-n-decyl ether, p-nitrosophenyl-lauric ether, p-nitrosophenyl-stearyl ether, p-nitrosophenyl-ceryl ether, p-nitrosophenyl-cinnamic ether, p-nitrosophenyl-tetrahydrofuryl ether, p-nitrosophenyl-furfuryl ether, p-nitrosophenyl-octylbenzyl ether, p-nitrosophenyl-p-methyl-benzyl ether, p-nitrosophenyl-p-chlorobenzyl ether, p-nitrosophenyl-propargyl ether, p-nitrosophenyl-isopropylpropargyl ether, p-nitrosophenyl-2- phenyl-ethyl ether, p-nitrosophenyl-methyl ether, p-nitrosophenyl-cetyl ether, p-nitrosophenyl-benzyl ether, p-nitrosophenyl-allyl ether, p-nitrosophenyl-oleyl ether, p-nitrosophenyl-isopropyl ether, p-nitrosophenyl-isoamyl ether, p-nitrosophenyl-2-octyl ether and p-nitrosophenyl-cyclohexyl ether.

The now preferred reactive ethers employed in the practice of the invention are those characterized by the structural formula

wherein each R is selected from the group consisting of: hydrogen, alkyl, alkenyl, alkinyl, phenyl, alkylphenyl, phenylalkyl, alkoxyphenyl, phenyl alkenyl, alkoxyalkyl, hydroxyalkyl, cycloaliphatic, halophenyl, nitrophenyl, furan and tetrahydrofuran, but the aforesaid

containing no more than 30 carbon atoms, and said ether thereby containing no more than 36 carbon atoms.

Preferred temperatures employed in the ether-p-nitrosophenyl-primary amine reaction, also referred to herein as amination, are generally in the range of about 150 to 100 C, more often in the range of about 25 to 750 C. Temperatures slightly above 160 C may be employed when desired, although at these levels undesirable side reactions occur, due at least in part to the decomposition of either the reactive ether or amination product, or both, with concomitant low yield. At temperatures below 0°C, some amination takes place, but the rate of reaction is generally too slow to be of any industrial importance, ie from the point of view of economic factors.

The reaction time used to carry out the amination is generally within the range of from about 1 minute to 48 hours, this reaction time being inversely related to the temperature, with the amine/acid ratio, and with the concentration. of the reagent. Thus, at a concentration of amine and reactive ethers of two molar each and at temperatures in the range of 35 to 500°C, using an amine/acid molar ratio of, for example, 10:1 to 20:1, the preferred reaction time is about 1/2 hour to 4 hours.

Similarly, using the same reactants and the same amine/acid molar ratio, at a concentration of reactants of 0.8 molar each and at a temperature of 25° C., the reaction time extends up to 20 to 24 hours or more. In contrast, at a temperature of 1600°C, a time of the order of 1 minute is often used and even under these conditions quite low product yields can be obtained due to undesirable side reactions.

The pressure does not materially affect the amination reaction, any pressure which keeps the reactants in the liquid phase being sufficient.

While the amination would proceed without the addition of an acid catalyst, the rate of reaction under such conditions would be extremely slow. It is therefore necessary that an acid catalyst be employed at all times in order to force the reaction to produce a high yield. Any acid can be used as a catalyst in the practice of the invention. However, in a particular case, it is advantageous to choose an acid catalyst whose amine salts are soluble, at least to a moderate degree, in the other constituents of the reaction mixture. In most systems the choice of preferred catalyst will also depend on the particular ether and the particular amine employed as reactants. Thus, by way of example, when aniline is employed as the aminating agent, it is advantageous to employ HCl and the sulfonic acid of toluene, which form soluble sols with the aniline; and again, when a monomethylamine is employed as the aminating reagent, sulfuric acid is a suitable catalyst. Examples of acids which can be employed as catalysts in carrying out the amination reaction are sulfuric, hydrochloric, phosphoric, periodic, perchloric, nitric, benzenesulfonic, methanesulfonic, orthophosphoric, pyrophosphoric, mono-, diet tri- chloroacetic and maleic; cuprous chloride, zinc chloride, boron trifluoride, ferric chloride, acidic earths, for example silica-alumina, superfiltrol, and acidic ion exchange resins such as, for example, polymerized sulfonated vinyl benzene , and others. Solid acid catalysts are particularly advantageously employed in the practice of the invention in bed form, eg, columns or layers, in fixed catalyst bed type operation. High oxygen acids such as nitric acid, perchloric acid and periodic acid are less desirable among inorganic acid catalysts because of the oxidative tendencies these acids exhibit during amination with concomitant decrease in carbon yield. amination product. Also, inorganic halides are among the least desirable catalysts due to a tendency, in some cases, to lead to undesirable side reactions and concomitant decreased yield.

The amination is generally carried out in the presence of a solvent, although in certain cases the use of a solvent can be dispensed with when, for example, aniline is used, which can play the role of both reagent and of solvent. A preferred solvent is the alcohol which corresponds to the reactive ether, since the alcohol solvent and the alcohol produced as a by-product of the amination are one and the same product and, consequently, the Separation of the solvent from the alcoholic by-product for recycling to the system is not a problem. However, if desired, any suitable solvent other than the preferred solvent described above can be used. Toluene and toluene-methanol mixtures are advantageously used as the solvent.

Glacial acetic acid is another advantageously employed solvent, particularly since in this case there is no need to add a separate acid catalyst, i.e. acetic acid functions as catalyst and solvent. . Other weak acids can be used likewise. The choice of solvent naturally depends on the solubility of the various constituents of the amination reaction mixture, so that, in any amination, a choice of solvent, if it is other than the preferred alcohol, can be based on the reagents used. . When a solvent is employed, all of the reactants, including the product, are present in the reaction mixture in a concentration on the order of about 1 to 6 molar. However, any proportion of solvent which retains the reactants in solution can be employed. Examples of solvents other than alcohols which can be employed are hydrocarbons, for example toluene, benzene, xylene, n-hexane and n-heptane; chlorinated hydrocarbons, for example, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, 1,1,1 trichloroethane, chlorobenzene and 1,2,4-trichlorobenzene; ethers, for example, diethyl ether, diethylene glycol, dimethyl ether, and esters, for example, ethyl acetate, n-butyl acetate, dimethyl formamide, tributyphosphate and ethylene glycol.

In carrying out the amination, the ether and amine may be charged to the system in any suitable proportions. Thus, although it is advantageous for the ether/aniline filler molar ratio to be 1:1, it can be varied to obtain a more complete conversion of one or the other of these reagents. Generally, however, an amine/ether molar ratio in the range of 0.5:1 to 2:1 is used. preferably in the range of about 2:1 to 40:1 and higher. The amine/acid molar ratio chosen can vary with the nature of the amine reactance. For example, when reacting methylamine, a suitable amine/acid molar ratio is on the order of about 1.5:1 to 6:1, often about 2:1, and when reacting aniline, an aniline/acid molar ratio in the range of about 5:1 to 20:1, often about 10:1, is generally employed.

When a suitably high amine/acid molar ratio is employed, eg, an aniline/acid ratio of 10:1 or greater, the rate of amination appears to be approximately proportional to the product of the reactant concentrations. Thus, when such amine/acid ratios are employed, a molar excess of amine relative to the reactive ether increases the reaction rate with a concomitant decrease in the time required for amination.

The etherification phase of the invention is illustrated with reference to the following examples.

Example 1 One hundred and twenty-three grams (1 mole) of p-nitrosophenol were charged at the same time as 355 cc of dry methyl alcohol and 145 cc of toluene in a two-liter reactor and then brought to a temperature of 450° C. in an atmosphere nitrogen. One cmc of concentrated sulfuric acid (0.018 mol) was then added to the p-nitrosophenol-alcohol-toluene reaction mixture thus obtained. The reactant-catalyst mixture was maintained, under nitrogen, at said above temperature for 52 minutes, after which the acid catalyst was neutralized by the addition of 1.5 moles of aqueous sodium hydrate followed by the addition of of 500 cmc Ide toluene to the neutralized mixture.

Methanol and water were removed by vacuum distillation from the neutralized solution thus obtained, each of them in the form of an azeotrope. of toluene, the toluene-methanol azeotrope being the one with the lowest boiling point and therefore being removed first.

By the resulting solvent exchange, ie unreacted toluene instead of alcohol, the unreacted p-nitrosophenol precipitated due to its low solubility in toluene. This precipitated p-nitrosophenol was removed by filtration from the toluene solution containing it, with recovery of 638 cmc of filtrate. This filter cake was dissolved in 300 cc of methanol, filtered to remove the catalyst salt, and then returned to the reactor. Fifty-five cc of methanol, 70 g of p-nitrosophenol and 145 cc of toluene were then also added to the reactor along with 1 cc of concentrated sulfuric acid to start a second cycle. The process was continued for 4 cycles. A total of 2.7 moles of p-nitrosophenol was employed. In the fourth cycle the catalyst concentration was doubled.

The filtrates in each cycle, i.e. the toluene solution of the product ether, were combined and stripped of the toluene under vacuum and the solution thus obtained was dissolved in two volumes of n-pentane and cooled to- 400 C to effect the crystallization of the p-nitrosophenyl-methyl ether produced. One hundred and ninety-two grams of dry p-nitrosophenyl-methyl ether, with a purity of over 95%, were recovered for an average conversion in each cycle of 55% and a yield of 88%. .

Example 2 One hundred and twenty-three grams (0.9 moles) of p-nitroso phenol of 90% purity were charged to a two liter nitrogen flushed reactor together with 500 cc of anhydrous ethanol. and 4.75 g (0.025 mole) of p-toluenesulfonic acid hydrate in 50 cc of ethanol, and the system was brought to 450 C and then maintained at this temperature, under nitrogen, for one hour. in the reaction mixture was neutralized with alcoholic KOH and the volume of the solution thus obtained was then reduced to 200 cc under vacuum Five hundred cc of n-heptane was then added and the system was again of stripping under vacuum of 300 cc. A charge of 250 cc of n-heptane was then added and the stripping operation was repeated. In this way, n-heptane replaced methanol as the solvent for the remix. - actionnel and p-nitrosophenol, and the latter, having low solubility in the n-heptane solvent thus obtained, precipitated and was removed by filtration. 360 cc of n-heptane solution of p-nitrosophenyl-ethyl ether (filtrate) were recovered and subjected to crystallization at -400° C. to give 54 g of p-nitroso-phenyl-ethyl ether crystals of a purity higher than 95 /o. The process conversion was 40%.

Example 3 The procedure of Example 2 was repeated except that the product p-nitrosophenyl alkyl ether was isolated by pouring the equilibrium mixture of ethanol, catalyst, p-nitrosophenol and p-nitrosophenyl ether in 10 volumes of H2O containing approximately 0.5 mole of NaOH. This was extracted twice with one volume of n-pentane. The volume of the thus obtained solution of p-nitrosophenyl-ethyl ether was reduced to 100 cc under vacuum and this mixture was allowed to crystallize.

The crystals were separated and dissolved in 50 cm of pentane and recrystallized. This twice recrystallized product was dried and subjected to carbon-hydrogen-nitrogen analysis, the results of which by comparison with the empirical molecular formula of p-nitrosophenyl alkyl ether are shown in the table below.

Calculated for Percent C8H9NO2 Found Carbon 63.6 63.7 Hydrogen 6.00 6.04 Nitrogen. 9.28 9.32 Molecular weight 151.2 152 The following alcohols were reacted with p-nitroso phenol in the presence of an acid catalyst at a temperature of the order of about 250 C to form the corresponding p-nitrosophenyl ether which, in the order of alcohols listed ,, was respectively: p-nitrosophenyl-methyl ether, p-nitrosophenyl-ethyl ether, p-nitrosophenyl-n-butyl ether, p-nitrosophenyl-cetyl ether, p-nitrosophenyl-benzyl ether, mono-p- nitrosophenyl ethylenic glycol, p-nitrosophenyl-allyl ether, p-nitrosophenyl-oleyl ether, p-nitrosophenyl-isopropyl ether, p-nitrosophenyl-sec-amyl ether, p-nitrosophenyl 2-octyl ether and p- nitro sophonyl-cyclohexyl. The results are given in the table as follows: acid catalyst Molar ratio, (p-toluene-sulfonic acid), Conversion Reactive alcohol alcohol/p-nitrosophenol molar ratio, based on initially added nitrosophenol acid/reactive p-nitrosophenol (2) Methanol 21 0.02 55 Ethanol 15 0.025 50 n-Butanol 9 0.02 45 Cetyl alcohol 2 0.16 13 Benzyl alcohol 8 0.16 20 Cellosolve (1) 9 0.16 20 Allyl alcohol 13 0.16 20 Oleyl alcohol 3 0.16 11 Isopropyl alcohol 11 0.04 10 Dry amyl alcohol 8 0.16 8-10 2-octyl alcohol 5 0.16 8-10 Cyclohexyl alcohol 8 0.16 8-10 (1) Monoethyl ether of ethylene glycol.

(2) Determination based on the ultraviolet spectrum.

Example 4 54 g of p-nitrosophenol, 300 cm of ethanol, 620 cm of toluene and 3 cm of concentrated sulfuric acid were charged to a two-liter reactor. The reaction mixture thus obtained was brought to a vacuum of 167 mm/Hg at 390° C. over a period of 18 minutes, after which the methanol already present in the reaction mixture was sparged through said mixture and discharged from the reactor. Sprinkling in this manner took place over a period of one hour with condensation of 585 cc of liquid. The temperature rose to 520 C during this period during which time the pressure was reduced to 136 mm/Hg. At the end of the one hour period, the reaction mixture was neutralized with caustic soda and analyzed by ultraviolet spectroscopy, which showed the presence of 49 g of p-nitrosophenetole corresponding to a conversion per pass of 74 /o.

Example 5 61 and 5 tenths g (0.5 moles) of p-nitrosophenol having a purity of about 980% was charged together with 230 cc (2.5 moles) of dry n-butanol into a reaction flask. 'one liter. 2 g and 2 tenths of p-toluene-sulfonic acid monohydrate were added and the reaction mixture thus obtained was maintained at 250C for a period of 15 minutes during which etherification took place to form p-ether. nitrosophenyl-n-butyl. At the end of this period, the etherification equilibrium was shifted to the ether side by sprinkling 500 cc of dry n-butanol vapor, added from outside the reactor, through the reaction mixture to remove water from the reactor. etherification at a pressure of about 26 mm/Hg and a temperature of 450° C. for a period of 60 minutes. The reaction mixture thus obtained was cooled to a temperature of −400° C., and the p-nitrosophenyl-n-butyl ether obtained was crystallized and separated by filtration.

The per-pass conversion of p-nitrosophenol to p-nitrosophenyl-n-butyl ether, determined by ultraviolet analysis, was 93%.

Example 6 61 g and 5 tenths of p-nitrosophenol and 230 cc of dry n-butanol were charged into a one-liter reactor by adding 0.5 cc of concentrated sulfuric acid with stirring, and the system was maintained under vacuum of 40 mm/Hg for 15 minutes at about 50-550°C. present in the etherification reaction mixture, with formation of methanol bubbles and rise of methanol bubbles through the reaction mixture; the n-butanol vapor sparged through the reaction mixture as described vented through the top of the reactor and substantially condensed.

After 115 cc of condensed distillate had been collected at the top, the temperature of the etherification reaction was raised to about 550 C and dry n-butanol was added-as a liquid-to the mixture continuously, for about 7 to 8 cc per minute, over a period of about 25 minutes with spraying into the reaction mixture and continuous spraying at the same rate during this period. The total distillate collected was 315 cmc, the reaction temperature not exceeding 560 C. The conversion of p-nitrosophenol to p-nitrosophenyl-n-butyl ether, determined by ultraviolet analysis, was 96.7 /o.

Example 7 3 g 69 hundredths of p-nitrosophenol were stirred at the same time as 46 cc of n-butanol and 1 cc of SO4H2 3 molar, in n-butanol in a 125 cc reactor, under nitrogen, for 3 hours, at about 25 vs.

10 cc of 2 N sodium hydrate and 30 cc of water were then added to the reaction mixture thus obtained, with formation of separate organic and aqueous layers, the latter containing p-nitrosophenol not reacting in the form of p -nitrosophenolate of sodium and acid salt, and the first having n-butanol and p-nitrosophenyl-n-butyl ether dissolved therein. These layers were separated and analyzed by ultraviolet spectroscopy, the organic layer containing 2.5 g of p-nitrosophenyl-butyl ether and the aqueous layer containing p-nitrosophenolate in an amount equivalent to 1.85 g of p-nitrosophenol. The conversion per passage of p-nitrosophenol to p-nitroso-n-butyl ether was 47%.

Example 8 3.69 g of p-nitrosophenol were stirred, at the same time as 46 cc of n-butanol and 1 cc of SO4H2 3 molar in n-butanol, in a 125 cc reactor, under nitrogen, for 3 hours at approximately 25° C. 10 cc of 2N sodium hydrate and 30 cc of water were then added to the resulting reaction mixture, forming separate organic and aqueous layers, the latter containing unreacted p-nitrosophenol under pnitroso-n-butyl acid salt and phenolate form, and the former having-n-butanol and p-nitrosophenyl-n-butyl ether dissolved therein.

These layers were separated and analyzed by ultraviolet spectroscopy, the organic layer containing 2.5 g of p-nitrosophenyl-butyl ether and the aqueous layer containing p-nitrosophenolate in an amount equivalent to 1.85 g of p-nitrosophenol . The conversion per passage of p-nitrosophenol to p-nitroso-n-butyl ether was 47%.

The following examples illustrate the amination phase of the invention.

Example 9 50.2g (0.33 mole) of p-nitrosophenyl ethyl ether was dissolved in 175cc of absolute ethanol in a one liter reaction flask and kept under a nitrogen blanket. A paste of 30.9 g (0.33 mole) of aniline and 1.51 g (0.015 mole) of concentrated sulfuric acid in 140 cc of absolute ethanol was added to the alcohol-ether solution. The mixture thus obtained containing the ether and the aniline was maintained in the nitrogen atmosphere with stirring at about 25° C. for 16.5 hours and was then neutralized with 22 cm of alcoholic KOH at 10% in weight. The precipitated p-nitrosodiphenylamine produced was then separated from the reaction mixture by filtration, washed with 3 50 cc portions of n-pentane and air dried. The filtrate and washings were combined and filtered to remove SO4E (2) and then evaporated over steam. The residue was dissolved in 50 cc of methanol and crystallized at about -300 C to give crystals of p-nitrosodiphenylamine which were then separated by filtration.

The combined crude product (56.3 g, 81.5% conversion based on reactive ether) was recrystallized from methanol to give 42.0 g of purified p-nitrosodiphenylamine having a point melting temperature of 144-145° C., the infrared spectrum of which was the same as that of a known sample of p-nitrosodiphenylamine. The results of a carbon-hydrogen-oxygen analysis of this product are as follows: Calculated for Percentage of weight Ct2Ht0N2O Found Carbon. 72.71 72.36 72.56 Hydrogen 5.09 5.19 5.24 Oxygen 8.08 8.35 Example 10 Example 11 The reaction method of Example 9 was repeated and the reaction mixture was analyzed by ultraviolet spectroscopy. A reaction conversion to p-nitro sodiphenylamine of 93% was obtained after 20.5 hours at room temperature.

10 cc of 4.0 M p-nitrosophenyl-methyl ether solution (0.040 mole) in methanol (40 volume percent)-toluene (60 volume percent) was added to 10 cc of a solution of 4.0 M aniline (0.040 mole)-0.2 M p-toluenesulfonic acid monohydrate (0.002 mole) in absolute methanol, contained in a 125 cmc centrifuge tube. This centrifuge tube was capped, flushed with nitrogen and placed in a bath at 50° C., the reaction mixture being stirred magnetically. After 90 minutes at 50°C, the reaction mixture was cooled in an ice bath and centrifuged to separate a crystalline product. The mother liquor was decanted and the dark blue solid was washed with 20 cc portions of n-pentane. The washed crystals were dried at 60° C., under reduced pressure, for 6.5 hours. The conversion by this method to p-nitrosodiphenyl-amine (90% purity) was 81% (7.1g) based on the reactive ether.

Example 12 The method of example 11 was repeated, but on a smaller scale and the products were analyzed by ultraviolet spectroscopy, the conversion to p-nitroso diphenylamine being 95/0 following a reaction for 90 minutes at 50 C.

Example 13 A reaction mixture, with a volume of 160 cc, resulting from the preparation of p-nitrosophenyl-butyl ether by reaction of p-nitrosophenol with n-butanol in the presence of p-toluene-sulfonic acid as catalyst, had the following composition, determined by ultraviolet spectroscopy: 0.436 mole of p-ni trosophenyl-butyl ether, p-nitrosophenol 0.0582 mole of nonreacted, the remainder being n-butanol.

The above reaction mixture was maintained under a nitrogen blanket and in a water bath, at a temperature of about 450 C. A solution (63 cc) of 42.6 g (0.457 mole) of aniline and 3.04 g (0.16 mole) of p-toluenesulfonic acid monohydrate in n-butanol was added to the reactants blanketed with nitrogen and the resulting reaction mixture was stirred at said above temperature for 2.5 hours, after the temperature was lowered to 20, with continuous stirring for 0.5 hour, the precipitated product (p-nitrosodiphenylamine) was filtered off. The product, a dark blue-black solid, was collected on the filter washed with three 100 cc portions of water and dried above P-'05 at laboratory temperature under reduced pressure. The crystals produced had a purity of 88 µ and were obtained at a conversion level of 90 µ.

Example 14 A reaction mixture of 7 cc of n-butanol, 41.1 g of p-nitrosophenyl-butyl ether, 25 cc of aniline and 3.3 g of aniline hydrochloride-the molar ratio of p-nitrosophenyl-butyl ether- butyl/aniline/HCl being 1/1.30/0.11-was stirred for 2 hours at 350° C., and at the end of this time 25 cc of n-hexane and 100 cc of water were added. The paste thus obtained was cooled to 10° C. and was filtered, and the cake was washed with 100 cc of nhexane. Analysis by ultraviolet spectroscopy of the total of the precipitated product and the filtrate showed a conversion to p-nitrosodiphenylamine of 91% based on the reactive ether.

The following ether-amine reactions were carried out in a closed system to yield a corresponding p-nitroso-N-substituted aniline product. These reactions were carried out either in ethanol or in methanol as the solvent, at temperatures ranging from 25-400 C, with an amine/acid molar ratio ranging from 2:1 to 20:1. In all cases the reactive ether was p-nitrosophenetole to form the corresponding p-nitroso-n-substituted aniline. Conversions, based on reactive ether, were at various levels up to 92%.

Table 1 Example? Amine Reagent Acid Catalyst Product 15 Methylamine SO iHs p-nitroso-N-methylaniline 16 n-Butylamine p-toluene p-nitroso-N-butylaniline sulfonic acid 17 Cyclohexylamine HCl p-nitroso-N-cyclohexylaniline 18 Benzylamine HCl p-nitroso-N-benzylaniline 19 Ethanolamine HCl p-nitroso-N-(-hydroxyethyl)aniline 20 Octadecylamine HCl p-nitroso-N-octadecylaniline 21 o-Toluidine HCI o-Methyl-p'-nitrosodiphenylamine 22 m-Toluidine HCl m-Methyl-p'-nitrosodiphenylamine 23 p-Toluidine HCI p-Methyl-p'-nitrosodiphenylamine 24 p-Anisidine SO4H p-Methoxy-p'-nitrosodiphenylamine 25 p-Ph6netidine HCl p-Ethoxy-p'-nitrosodiphenylamine 26 p-Chloroaniline SOtH2 p-Chloro-, p'-nitrosodiphenylamine 27 p-Phenylenediamine HCI p-Amino-p'-nitrosodiphenylamine 28 p-Cyanoaniline SO4H2 p-Cyano-p'-nitrosodiphenylamine 29 p-Nitroaniline HCI p-Nitro-p'-nitrosodiphenylamine 30 p-Amino-benzoic acid HCI p-Carboxyl-p'-nitrosodiphenylamine Example NO Amine reactant Acid catalyst Product 31 o-Phenylenediamine HCl o-Amino-p'-nitrosodiphenylamine 32 m-Aminophenol HC1 m-Hydroxy-p'-nitrosodiphenylamine 33 p-Phenylenediamine HC1 N,N'-bis(p-iiitrosophenyl)-p,p-diaminodiphenyl-methane 34 p,p'-Diaminodiphenyl-SO4H2 N,N'-bis(.p-nitrosophenyl)-p,p'^diaminodiphenyl -methane methane 35 Benzidine HCl N,N'-bis(p-nitrosoph6nyl)benzidene Example 36 15.7 cc of methylamine 0.86 molar in methanol and 6 mcc of SO4HS 0.5 molar in methanol were introduced with 0.75 g of p-nitrosophenetole and the mixture thus obtained was stirred at 250° C. for 23 hours. A sample of the reaction mixture thus obtained was analyzed by ultraviolet visible spectroscopy and a conversion of the ether to p-nitrosophenyl-N-methylaniline of 41% was observed.

The following examples 37-44 illustrate combined sequences of etherification and amination phases.

Examples 37-44 A series of etherification reactions were carried out, in each of which an alcohol was reacted with p-nitrosoph6nol at 25°C, in the presence of p-to luenesulfonic acid as a catalyst to form a corresponding p-nitrosophenyl ether, according to the process described in the preceding examples. Aniline was mixed with the etherification reaction mixture thus obtained, in each case, and reacted with the ether contained therein at about 25° C. to produce p-nitrosodiphenylamine, sufficient p-toluene acid - sulphonic catalyst being present in the reaction mixture of etherification thus obtained to catalyze the aniline-ether reaction. Conversions to p-nitroso diphenylamine, based on the reactive ether, were at various levels up to. plus ide 90 0/0. The amine/ether and amine/acid molar ratios were about the same as those in Table I.

The alcohols reacted separately with p-nitroso phenol in the presence of the acid catalyst to form the corresponding ether are as follows, aniline being then added to the etherification reaction mixture thus obtained to form p-nitrosophenylamine as described above.

Table II Example N Alcohol Ether produced 37 2-Octyl Ether p-Nitrosophenyl-2-octyl alcohol 38 Cyclohexyl p-Nitrosophenyl-cyclohexyl alcohol 39 2-Ethoxyethyl p-Nitrosophenyl-ethoxy6ethyl alcohol 40 Oleyl p-Nitrosophenyl-oleyl alcohol 41 Benzyl alcohol p-Nitrosophenyl-benzyl 42 Allyl alcohol p-Nitrosophenyl-furfurylallyl 43 p-Nitrosoph6nyl-furfuryl furfuryl alcohol 44 p-Nitrosophenyl-cetyl c6tyl alcohol The process of the invention is further illustrated with reference to the schematic tables of sequence of operations in the appended drawings, in: FIG. 1 illustrates the amination phase; the figs. 2a, 2b and 2c illustrate a process for manufacturing p-nitroso-N-substituted anilines starting from phenol as the basic raw material; fig. 3 illustrates a discontinuous type process using the p-nitrosophnol obtained from the primitive phenol as in the process of FIG. 2; the figs. 4a-b illustrate another implementation of the process for the manufacture of p-nitroso-N-substituted anilines but differing from that of FIGS. 2a-c, with respect to steps involving recovery of p-nitrosophenol and unreacted reactant amines for return to the system; fig. 4c illustrates a succession of phases after the amination which can replace those of FIGS. 4a-b; and fig. 5 illustrates a batch-type operation implementation of the overall method of FIGS. 4a-c; the figs. 6 and 7 are illustrative implementations of the etherification phase in which the reactive alcohol is employed both as a reactant and as a solvent with subsequent solvent exchange (fig. 6) and in which a complementary solvent is initially used for etherification, with or without subsequent solvent exchange, as desired (Fig. 7); fig. 8 illustrates the fractional distillation of water of etherification out of the ether-forming reaction mixture during etherification to cause a shift in equilibrium towards the ether side, with concomitant increase in conversion per pass, all in the same area; fig. 9 illustrates the etherification and the spraying phase carried out concurrently in the same reaction vessel; fig. 10 also illustrates the etherification and the spray phase carried out concurrently, except that the initial etherification is carried out in a first reaction zone without the spray phase and is completed in a second zone with concurrent removal of the etherification water in accordance with the concept of sprinkling.

With reference to fig. 1, a p-nitrosophenyl ether and an alcohol, for example an alkanol, advantageously in the form of a mixture via line 1, are introduced into the amination zone 2 at the same time as a reactant amine and the acid catalyst for the amination via line 3. The molar ratio of ether to amine charged in zone 2 is preferably on the order of about 1:1, and the reaction mixture contains the acid in a ratio amine/acid molar ratio on the order of about 2:1 to 40:1, as described above. The alcohol introduced via line 1 functions as a solvent for the amination and preferably corresponds to the ether charged with it, as discussed above. The volume of alcohol solvent in the amination zone 2 is largely a matter of choice provided the reactants are retained in solution, the amount of alcohol generally constituting 25 to 50 volume percent of the titmouse. amination reaction.

The amination zone 2 is maintained at a temperature generally within the range described above and more often within the limits of about 15 to 1000 C. The residence time in zone 2, generally comprised within the reaction time range described above, is more often between about 12 and 3 hours. The p-nitroso-N-substituted aniline produced, having a low solubility in solvent alcohol, precipitates out of the reaction mixture and is discharged, pulped with the remaining constituents of the reaction mixture, as the total output product via the pipeline. 4 to separation zone 5 which includes various means for breaking down this output product from line 4 into separate product and component streams. Zone 5 therefore contains any suitable combination of elements such as centrifuge, separation means, neutralization means, filtration means, rectification means, crystallization means, designers and others for the dissociation of said output product. Consequently, the p-nitroso-N-substituted aniline can be evacuated from zone 5 in the form of a paste in the solvent alcohol or in the form of dry crystals via line 6. The alcohol and the ether which have not entered into reaction, generally in the form of a mixture, are discharged from zone 5 via line 6a for recycling, if desired, to zone 2 via line 1, the unreacted reactive amine is discharged via the line 6b also for recycling. if desired, to zone 2 via line 3, and the catalyst salt produced by the neutralization is discharged via line 6c.

The product coming from line 6, in the form of a paste or of dry crystals as desired, is, although it can be sent to storage, advantageously sent directly to any appropriate subsequent use, alone or in mixture with other solvents or reagents (not shown) introduced into line 6.

The most common use of the product from Line 6 is as an intermediate in the manufacture of its diamine derivatives which generally involves, at least as an initial step, the reduction of the nitroso-group to the amine. Various other uses of the product from line 6 are well known in the art.

With reference to fig. 2a, the phenol is nitrosated in nitrosation zone 12 by reaction with nitrous acid formed by the in sirli reaction, in zone 12, of nitrite and suitable acid reagents well known in the art. In general, an alkali metal nitrite, preferably sodium nitrite, is reacted. with an inorganic mineral acid, preferably sulfuric acid, for this purpose. Thus, according to a method applicable to all of these reagents, but illustrated with reference to the reagents preferred herein, namely sodium nitrite and sulfuric acid. separate streams comprising water, molten pllenol, aqueous sodium nitrite, aqueous sodium hydroxide and aqueous sulfuric acid are introduced into zone 12 via lines 7,8,9,10 and 11 respectively, preferably in relative proportions, to give nitrous acid in a stoichiometric excess of about 10"/o of reactive phenol. line 18, is-on the basis of weight: water 87/o, phenol 5/0; sodium hydroxide 0.6/o; sodium nitrite 4/o; acid salt 0.4/o, and sulfuric acid 3 /o The optimum proportions are dictated to a large extent by the choice of reagents employed in zone 12.

By carrying out the nitrosation in the zone 12, it is possible advantageously to use the negative heat of the dissolution of the sodium nitrite in the water by forming an aqueous solution of nitrite in the pipe 9 just before its introduction into the nitrosation zone, this solution aqueous of newly formed nitrite thereby functioning as a coolant to help bring reaction zone 12 to the desired level, which is generally on the order of about 20 to 30 C. The p-nitro sophenol formed in zone 12 precipitates out of the reaction mixture.

The total output product, a paste, is removed via line 13 to separation zone 14 which includes suitable means for separating solid p-nitrosophenol for the etherification described below. Zone 14 can, for example, be a centrifugal separation system or, if desired, it can constitute a filtration system comprising two separate filtration apparatuses for continuous filtration in an apparatus with concurrent removal from the other apparatus of the previously collected precipitated p-nitrosophenol. In either case, the water-wet p-nitrosophenol is separated and removed from zone 14 via line 15 for subsequent drying in drying zone 31. A reactive alcohol for the etherification described above after with reference to area 34-preferably at least partially immiscible with water such as n-butanol, and illustrates with specific reference to n-butanol is added to the system via lines 19, 19' and 21 not only to serve of reagent-solvent during the etherification described below but also to be available for distillation in zone 31 as a constituent of an n-butanol-water distillate for drying the p-nitrosophenol in zone 31. When adding n-butanol to the system via line 19', it also functions as a carrier for wet p-nitroso phenol from area 14.

If desired, n-butanol can be added to line 21 via lines 19, 20, separation zone 14 and line 15, thereby helping to remove solid p-nitrosophenol from the media. of separation used. In any case, the charge introduced into zone 31 generally contains from about 60 to 90% by weight of n-butanol, from 10 to 30% by weight of p-nitrosophenol, the remainder being water. . The residual liquid, that is to say stripped of the solid p-nitrosophenol, is evacuated from zone 14 via lines 16 and 17 for use outside the process or else is partly recycled to zone 12 via line 18; it includes water, acid salt and some dissolved nitrosophenol. It is generally more advantageous to send the current from line 16 to a use external to the process.

A slurry of n-butanol, water and p-nitrosophenol from line 21 is subjected to distillation in zone 31, under vacuum, to remove water from this slurry, to some extent if not completely, in the form of a slurry. of constituent of an n-butanol-water distillate. The distillation in zone 31, which is advantageously carried out under vacuum to facilitate the removal of water, results in a bottoms product containing less than about 0.2% water by weight. Zone 31 is therefore advantageously operated at a pressure in the range of about 20 to 50 mm/Hg and at a temperature in the range of 25 to 60°C. temperature and pressure conditions outside these ranges.

The dry paste, that is to say substantially free of water, is discharged from zone 31 via line 33 to etherification zone 34 with an acid, for example sulfuric acid, from line 36, this acid being advantageously dissolved in dry n-butanol which serves as its carrier, this n-butanol also serving to compensate for the n-butanol lost from zone 31 via line 32. Although the acid does not does not need to be added with the dry n-butanol carrier, it is important that it is in any case added in the dry state, since the presence of water must be reduced to a minimum in zone 34 to because of its deleterious effect on the etherification equilibrium reaction.

The p-nitrosophenol in zone 34 is etherified with n-butanol to form the corresponding ether, ie p-nitrosophenyl-butyl ether. The molar ratio of alcohol to p-nitrosophenol introduced into zone 34 ranges from about 1:1 to 100:1; and the molar ratio of acid to p-nitrosophenol introduced into zone 34 ranges from about 0.005:1 to 0.2:1. - fluids in zone 34 are generally of the order of 10 to 30 /0 of p-nitrosophenol, 70 to 90 /o of n-butanol, and 0.20 to 2 /o of acid, the n-butanol as well added as both reagent and solvent. Zone 34 is generally maintained at a temperature in the range of 0 to 150°C, and more often in the range of about 15 to 70°C, and at any suitable pressure sufficient to maintain liquid phase reactants. However, since the distillation in zone 31 is preferably carried out under sub-atmospheric pressure and since the distillation in zone 38, FIG. 2b, described below, is also advantageously conducted at sub-atmospheric pressure, it is very advantageous that zone 34 is also at sub-atmospheric pressure, for example about 20 to 50 mm/Hg from the point view of the problems involved in the flow of products through these three zones, particularly since the level of pressure employed in zone 34, assuming a reaction in the liquid phase, has no influence. measurable effect on the conversion achieved in said area.

The reaction time in zone 34, under the preferred temperature conditions, is generally in the range from 2 to 500 minutes, although reaction times outside this range can be employed, particularly if they are inversely related to etherification temperatures in zone 34 outside the temperature range described above.

The maximum conversion in zone 34 is generally on the order of 50-55 /o and is determined by the equilibrium of the etherification reaction, which is the following: p-nitrosophenol + p-nitrosophenyl alcoholic ether + water. The above equilibrium equation clearly shows that by removing the water of etherification the reaction can be made to proceed more completely towards the formation of ether. Thus the total output of the etherification zone 34 is evacuated via line 37, in the liquid phase, at the top of the water removal zone 38, see fig. 2b, which it is made to cross by flowing downwards. Dry n-butanol is introduced into a lower portion of this zone 38 via line 35 and is sent as a vapor through the downwardly flowing liquid mass in said zone 38, and this under a pressure under atmospheric pressure of approximately 20 to 50 mm/Hg for example, a temperature of the order of approximately 20 to 500 C being advantageously employed. Under these conditions, the n-butanol in vapor form rises in contact with the liquid mass in zone 38 and condenses with repeated revaporization and recondensation, the water content in the n-butanol vapor at high water content, approaching, for example, the water content of the n-butanol-water azeotrope, which is about 38% water, but being generally less than this. Zone 38 functions as a vacuum spray distillation to remove water of etherification from the etherification reaction mixture. The n-butanol sparging through the liquid mass as described exits zone 38 together with the water as a mixture of vapors, via line 39. the water of etherification being substantially completely removed, the etherification equilibrium is shifted to the ether side so as to raise the conversion by shifting zone 34 to a value significantly above the value of 50-55 / o described above. Thus, under spray conditions in zone 38, conversions of up to 90% and higher are obtained. n-Butanol as etherification reagent-solvent is particularly advantageously applied in its use in zone 38 since the vapor thus obtained in zone 38 is suitable for water and therefore a large proportion of water (eg 20-30 μ) is removed via line 39 per volume of n-butanol removed with it. Thus n-butanol can be distilled in a relatively small amount to remove substantially all of the water of etherification in the equilibrium displacement phase.

The water-free bottoms product is removed from zone 38 via line 41 and includes product ether, unreacted p-nitrosophenol, n-butanol and acid catalyst; it is sent to neutralization zone 42 together with an aqueous neutralizing agent from line 43, usually an aqueous alkali metal hydroxide such as sodium hydroxide. Neutralization zone 42 is maintained at any suitable temperature to effect neutralization of acid from line 41 and conversion of p-nitrosophenol therein to the corresponding phenolate for separation described below. Zone 42 can therefore advantageously be operated at temperatures of the order of 20 to 350 C.

Two phases separate in neutralization zone 42, namely an organic phase and an aqueous phase, the relative densities depending on the relative concentrations of n-butanol and reactive ether in the output product from line 41. organic phase 46 comprises the product ether dissolved in n-butanol, accompanied by a small proportion of water. The aqueous phase 44 comprises the nitrosophenolate mentioned above, water, acid salt from the neutralization, and n-butanol.

The aqueous phase 44 is evacuated via line 48 to the acidification zone 51 at the same time as an aqueous acid such as sulfuric acid via line 53, the zone 51 being maintained at any temperature suitable for the acidification of the phenolate to p-nitrosophenol, for example, 20-350 C. Distinct organic and aqueous phases are formed in this zone 51, namely an aqueous phase 52 and a lighter organic phase 50, this organic phase 50 comprising a solution p-nitrosophenol non reacts in n-butanol removed via line 54 for recycling to the system via drying and distillation zone 31, and the aqueous phase 52 containing extracted catalyst salt from the neutralization, water and some n-butanol removed via line 55. n-butanol as an extraction solvent for the p-nitrosophenol and supplementing the n-butanol from line 48 is added to zone 51 via line 64 .

The organic phase 46 is removed from the neutralization zone 42 via line 47 to the amination zone 49. The stream in this line 47 generally contains about 50 to 65% by weight of ether p -nitrosophenyl-butyl, from 2 to 5% by weight of water, the balance being n-butanol. Aniline-which represents the reactive amine in zone 49-is sent to this zone 49 via line 56 together with an acid as catalyst for the amination, for example aqueous HCl. The acid catalyst used in the amination reaction in zone 49 can be the same as that used in the etherification of zone 34. The total charge for zone 49 generally contains p-nitrosophenyl-butyl ether in a ratio molar ratio with aniline on the order of about 1:1, and in a molar ratio with acid on the order of about 10:1.

However, as discussed above, other suitable ether/aniline and aniline/acid ratios may be employed. The amination zone 49, which can advantageously be maintained at a temperature comprised in the range going from approximately 0 to 160° C., is in the present embodiment, that is to say, the reaction involving aniline-preferably at 25 to 50°C approximately, the corresponding residence time generally being at least half an hour and possibly up to approximately 4 hours. Any suitable pressure can be used in the zone 49, a pressure of the order of atmospheric pressure being generally employed.

In the amination of zone 49 the aniline reacts with the p-nitrosophenyl-butyl ether component of the stream from line 47 to produce the corresponding p-nitro sodiphenylamine which precipitates due to its low solubility in the reaction mixture thus obtained. . The total product exiting zone 49 comprises precipitated p-nitrosodiphenylamine, unreacted ether and aniline reactants, acid catalyst, water and n-butanol, and the resulting paste is sent via line. 57 to a suitable separation zone 58 for separation of the crystalline p-nitroso phenylamine from the residual liquid. The separation zone 58 comprises any suitable means for separating the precipitated product and may be, for example, a centrifugal separation system or a filtration system comprising two filtration apparatuses to provide continuous filtration in an apparatus with concurrent removal from the other device of the previously collected precipitate. In any event, the solid p-nitrosodiphenylamine produced is removed from area 58 by any suitable means for recovery or further use. Thus, in a preferred practice of the invention the precipitated product from zone 58 is dissolved in acetone or other suitable agent to n-alkyl the produced p-nitrosodiphenylamine to form the derivative corresponding N-alkyl-p-amino-diphenylamine, as described below, by introducing the alkylating liquid via line 60 into contact with the p-nitrosodiphenylamine produced in separation zone 58 and evacuation in line 67 of the solution as well formed.

Residual liquid is removed from area 58 via line 59 and includes a small proportion of p-nitrosodiphenylamine, unreacted amine and ether reactants, acid, n-butanol and water; it is sent directly to the distillation zone 61 where it is. distilled, preferably under vacuum, to remove the water overhead with the n-butanol, as an overhead, via line 62. The bottoms from the distillation zone 61 are recycled to the amination in area 49 via line 63.

The p-nitrosodiphenylamine solution in line 67 comprises the alkylating agent and p-nitrosodiphenylamine with some n-butanol and is sent to area 68 where it is reacted, reduced to form the derivative corresponding p-amino or, by reductive alkylation, a combination of reduction and condensation with a carbonyl compound, to form N-alkyl-N'-phenyl-p-phenylenediamine. Thus zone 68 contains a suitable hydrogenation catalyst, alone or with a suitable condensation catalyst, which is generally an acid when a ketone is employed as the alkylating agent. When the reduction alkylation is carried out, both types of catalyst (hydrogenation and condensation or alkylation) can be used as a mixture. Therefore, in one implementation, a solid granular hydronation catalyst, for example a nickel catalyst fixed on a support, can be mixed with an acid alkylation catalyst, for example phosphoric acid, and brought into contact with any manner desired with free hydrogen and feed from line 67 under appropriate conditions of temperature, pressure and time for reductive alkylation.

The conditions, temperature and time employed in zone 68 naturally depend on the particular catalysts employed. In carrying out the reductive alkylation with the use of a single catalyzing mass, that is to say a mixture of the two catalysts, it is of course important that these catalysts be chosen to cause the respective reactions under the same conditions. temperature, pressure and time. An example of a pair of catalysts is palladium on carbon (hydrogenation) and phosphoric acid, both of which may be employed, in zone 68 at a temperature in the range of 25 to 700C for a period of 1 to 4 hours at pressures in the range of atmospheric pressure to 106.48 kg/cm2 and above. Any suitable hydrogenation and condensation or alkylation catalyst can be chosen from those well known in the art. Particularly suitable hydrogenation catalysts are platinum and palladium, each on carbon support, and the supported nickel type catalyst. Examples of alkylation catalysts are catalysts of the silica-alumina type and acids such as phosphoric acid or sulfuric acid.

In accordance with a now preferred implementation, a solid granular catalyst mixture is supported in zone 68. The p-nitroso diphenylamine solution from line 67 is introduced into the top of zone 68 and passed into This is in countercurrent contact with upward flowing hydrogen from line 69. Residual hydrogen is vented from zone 68 via line 70. The total liquid product, with some hydrogen, is vented from area 68 via line 71 and in this case includes hydrogen, n-iso propyl-N'-phenyl-p-phenylenediamine, acetone, n-butanol and water.

The total output from zone 68 in line 71 is fed to vacuum distillation zone 72 maintained at conditions suitable for removal of hydrogen from above via line 75 for recycling, if the it is desired, via line 69, and for the distillation of n-butanol and acetone separated overhead distillates via lines 73 and 74 respectively, the residual distillation product being discharged via line 76 to the distillation zone. flakes 77, operation followed by the recovery of the product in flakes via line 78.

As illustrated, the n-butanol-water overhead streams in each of lines 73,62,55,39 and 32 are recycled via line 80 to an n-butanol rectifier 79 from which the water is removed via line 81 (Fig. 2a), the n-butanol being removed via line 82 for recycling to the system via line 19 or, if desired, via any one or more of lines 36,35 and 64 .

With reference to fig. 3, a paste, the same as that of pipe 21 of FIG. 2a, is sent to zone 101 which, in the order indicated, serves as a zone for drying, etherification, distillation, neutralization and acidification, the product leaving it being discharged via line 102 to an amination zone 107 and of combined distillation described below.

The paste of p-nitrosophenol, n-butanol and water in line 21 as it passes through zone 101 is first held at an appropriate temperature for drying under vacuum to remove the water component, the conditions temperature, vacuum distillation and duration of zone 31 of FIG. 2a being employed with advantage. Additional dry n-butanol and an acid catalyst suitable for etherification ~ for example sulfuric acid - both coming from line 103, are introduced into zone 101 for etherification of the p-nitrosophenol as described in reference to etherification in area 34 of FIG. 2a, and etherification is carried out. The system in area 101 is then maintained under the same vacuum and temperature conditions as in area 38 of FIG. 2b to effect the removal of etherification water as a component of an n-butanol-water overhead via line 104 by spraying, using n-butanol, from line 100, as a spraying agent, as illustrated with reference to area 38 of FIG. 2b. A suitable neutralizing agent, preferably an aqueous alkali metal hydroxide, is then added to zone 101 via line 106 to effect neutralization of the acid catalyst and unreacted p-nitrosophenol, the reaction mixture containing ether. corresponding in composition to that of zone 42 of FIG. 2b, which causes the reaction mixture to separate into aqueous and organic phases corresponding respectively to phases 44 and 46 of zone 42. The organic phase thus obtained, that is to say similar in composition to phase 46 of the fig. 2b, is discharged via line 102 to amination zone 107.

The residual aqueous phase in zone 101 is then acidified with additional sulfuric acid introduced via line 108 to convert the sodium nitrosophenolate therein to p-nitroso phenol for disposal via line 109 for reuse with n-butanol in the etherification reaction in zone 101. The n-butanol, water and catalyst salt from the acidification which constitute the residue are removed from zone 101 via line 111, the composition of this residue corresponding to the product found in line 55 of FIG. 2b.

The organic phase from line 102 is sent to zone 107 together with an amine which is an aminating agent for it and acid, from line 112, the amine, the water and the acid being preferably mixtures. The reaction mixture thus obtained in zone 107 is maintained under the amination conditions of zone 49 of FIG. 2b.

This reaction mixture in zone 107 is then subjected to the distillation conditions of zone 61 of FIG. 2c, whereby the water with the butanol is distilled overhead via line 113 and the residual product is withdrawn via line 114 to the separation zone 116 which may be a filtration or centrifugation zone. and wherein the aniline-p-nitroso-N-substituted is separated, the residual liquid being recycled in part, if desired, to the amination in zone 107 via line 117 and the remainder, or the whole portion, if desired, being withdrawn via line 119. The solid product is evacuated in dry or wet form, as desired, via line 118, for storage or later use, for example, in the alkylation phase. reduction of zone 68, fig. 2c.

With reference to Figs. 4a-c, a dry paste, that is to say practically free of water, of p-nitrosophenol in n-butanol and an acid catalyst are introduced into the etherification zone 122, preferably in the form of a mixture, via lines 120 and 121, in proportions similar to those introduced into area 34 of FIG. 2a for an etherification identical to that described with reference to said zone 34. The total output product of this zone 122, similar in composition to that of zone 34, fig. 2a, contains the product ether, i.e. p-nitroso-phenyl-butyl ether, at a conversion per pass of the order of 50 to 55% and is discharged via line 123 to to zone 124 where it is countercurrently contacted with upwardly flowing n-butanol vapor under spray conditions for removal of water of etherification from said output to to thereby cause a displacement of the equilibrium of the etherification reaction towards the ether side to give a conversion per passage of the order of 95 to 99%. The conditions used in zone 124 are the same as those in zone 38, FIG. 2b. dry n-butanol being added to zone 124 via line 126 with removal of n-butanol-water via line 125. Residual output product, substantially free of water, is removed from zone 124 via line 127 directly to the amination zone 128 as well as the reactive amine, anilinea in this case, and the acid catalyst for the amination, often HCl, from line 129, the proportions and conditions for the reactants being the same as those used in carrying out the amination of zone 49, FIG. 2b. Amination of p-nitrosophenyl-butyl ether with aniline as the aminating agent takes place in zone 128 to produce the corresponding amine derivative, in this case p-nitrosodiphenylamine. The product, i.e., the p-nitroso-N-substituted aniline, precipitates out of the reaction mixture in zone 128 and the total output therefrom, a paste,

* is discharged via line 130 to separation zone 131 which may be any suitable means of separation, as described with reference to separation zone 58 of FIG. 2b. The residual liquid from area 131 includes water, unreacted reactive ether-i.e., unreacted p-nitrosophnyl-butyl ether-unreacted n-butanol, some unprecipitated so-N-substituted p-nitro aniline, in this case p-ni trosodiphenylamine, some unreacted p-nitrosophenol, HCl and SO4H2, and is discharged via line 132, together with aqueous alkali metal hydroxide-for example, NaOH-coming from line 134, to the naturalization zone 133, the amount of NaOH coming from line 134 being sufficient not only to neutralize the acid catalyst by from line 132 but also to react with the non-reacting p-nitrosophenol therein to form the corresponding phenolate. An organic phase 136 and an aqueous phase 137 are formed in zone 133.

The aqueous phase 137 comprises water, NaCl, SONa, sodium p-nitrosophenolate and n-butanol and is evacuated from zone 133 via line 138, at the same time as acid coming from the pipeline 139, up to the acidification zone 141, fig. 4a, wherein sodium p-nitrosophenolate is acidified to form p-nitrosophenol which precipitates in area 141.

A resulting paste of p-nitrosophenol in water together with the remaining constituents from line 138 is discharged via line 142 to separation zone 143 which includes any suitable means for separating the p- nitrosophenol precipitated from the mixture containing it and coming from line 142. Zone 143 may therefore comprise a filtration system or a centrifugal separation system as described in more detail above with reference to separation zone 58 of FIG. 2b. The residual liquid is evacuated from zone 143 via line 144.

The wet solid p-nitrosophenol is discharged from zone 143 via line 146 to water wash zone 147 to be washed with water from line 148 and discharge of the wash waters via the lines 149 and 144. The water-wet p-nitrosophenol is removed from zone 147 via lines 150 and 151, together with additional n-butanol from line 150, to the distillation stage. 152 maintained under the same drying distillation conditions as those described above with reference to zone 31 of FIG. 2a, and with removal of the n-butanol-water distillate via line 155. A dry paste of p-nitrosophenol in n-butanol is removed from zone 152 via line 153 and line 121 for recycling to the production zone. etherification 122.

The organic phase 136 in area 133 includes some p-nitroso-N-substituted aniline, i.e., p-nitrosodiphenylamine in this case, n-butanol, and ether and aniline reactants not reacted and is discharged via line 154, along with aqueous HCl from line 156, to acidification zone 157 for conversion of unreacted aniline component to aniline hydrochloride or in any case into a water-soluble aniline salt. Under these conditions, an organic phase 159 and an aqueous phase 161 are formed in zone 157 and the soluble aniline salt thus formed is separated from the p-nitrosoaniline-N-substituted by extraction in phase 161. The aqueous phase 161 comprises n-butanol, aniline hydrochloride and water and is removed from zone 157 via line 162 to solvent removal zone 163 for distillation of the water as a distillate. n-butanol-water, evacuation of the residual liquid, namely aniline hydrochloride, n-butanol and p-dinitrosodiphenylamine, via line 166 for recycling to the amination zone via lines 127 and 127.

Organic phase 159 comprises p-nitroso diphenylamine not precipitated in zone 128, together with some ether in n-butanol and is removed from zone 157 via lines 165 and 167 for recovery. of the product or its subsequent use as desired. The p-nitroso-N-substituted aniline produced from separation zone 131 of FIG. 4a is recovered via line 135 in any suitable manner. In a now preferred embodiment, acetone is introduced into zone 131 via line 140 in solution with the solid product, i.e. p-nitrosodiphenylamine, and the solution thus obtained is discharged. via line 135 to line 171, fig. 4b, together with the organic phase removed from zone 157 via lines 165 and 168, as feed, via line 171, to reductive alkylation such as that described herein with reference to zone 68 and phases associated therewith of fig. 2c. However, any suitable solvent or carrier via line 135 can be used to remove the solid product from zone 131 for transfer to line 171 with the organic phase from line 168 for any recovery and/or phase. desired use of the product. If desired, the product from zone 131 can be discharged in any suitable form from line 135 via line 139.

The order of the phases of neutralization and acidification of the zones in fig. 4b, 133 and 157 respectively, can be reversed if desired. Thus, with reference to FIG. 4c, that zones 157′ and 133′ are acidification and neutralization zones similar to the respective zones 157 and 133 of FIG. 4b. Therefore, as shown with reference to FIG. 4c, the residual liquid coming from the separation zone 131 of FIG. 4a and evacuated via the pipe 132 to 132′ at the same time that the water or the aqueous HCl coming from the pipe 156′ is sent via the pipe 132″ into the zone 157′, the conditions of this zone 157′ being the same as those of zone 157 of Fig. 4b Although the proportion of catalyst in the amination of zone 128 of Fig. 4a is considerably less than that of the reactive aniline, the proportion of HCl and Residual unreacted aniline from line 132 may be about 1:1 or slightly more, in which case just add water to zone 157' through line 156'. sufficient HC1, if needed from line 156', is that required to ensure complete conversion of the unreacted aniline in the residual liquid from line 132 to the salt soluble in water, so that the aniline, like the hydrochloride, is extracted into an aqueous phase 161'. This aqueous phase is evacuated from the zone 157' via the pipe 162' to a stripping phase like that of the area 163 of fig. 4b for removal of water as an n-butanol-water distillate to yield a residue of aniline hydrochloride, n-butanol and p-nitrosodiphenylamine as a bottoms product for reference to 1 friendship.

The organic phase 159', in zone 157', comprises n-butanol, ether, a little p-nitrosodiphenyl-amine and p-nitrosophenol does not react and is evacuated via line 154' at the same time an aqueous alkali, typically an alkali metal hydroxide, from line 134' to zone 133' where phases 136' and 137' form and separate. The aqueous phase 137′ is the same as the phase 137 of the zone 133 of FIG. 4b and is evacuated via line 138' for subsequent operations identical to those described above with reference to the aqueous phase in line 138 of FIG. 4b. The organic phase 136′ has the same composition as the phase 136 of the zone 133 of FIG. 4b, except that it is aniline-free and is removed via line 168' for further processing such as the reductive alkylation described above with reference to the organic phase removed from area 157 via lines 165 and 168 until reductive alkylation.

With reference to fig. 5, a paste of p-nitrosophenol, n-butanol and sulfuric acid, composition similar to that found in line 121 of FIG. 4a, is introduced via line 121' into etherification zone 501 and maintained under the temperature, pressure and time conditions for etherification described above with reference to zone 122 of FIG. 4a for the etherification of p-nitrosophenol with n-butanol to form the corresponding p-nitrosophenyl-butyl ether. During the etherification reaction dry n-butanol from line 502 is introduced into zone 501 and is sent upwards there as a vapor through the etherification reaction mixture and is vented with it. than water as distillate via line 503 to provide the spray phase to cause an equilibrium shift to the ether side to provide a higher yield of ether, for example, of the order of 95/o and above as described above. Following the sprinkling and equilibrium displacement operation, the total output product is removed from zone 501 and sent directly to amination zone 506. At this point zone 506 is operated in the amination conditions described above with reference to area 128 of FIG. 4a for the amine-ether reaction to form the corresponding p-nitroso-N substituted aniline, the amine reactivating—in this case the aniline—being introduced into zone 506, at the same time as hydrochloric acid as catalyst for amination, via line 508. After the amination phase, a gaseous alkaline agent is introduced into zone 506 via line 507 and under these conditions the acid present in the amination reaction mixture obtained is neutralized and the p-nitrosophenol not reacted therein is converted into the corresponding phenolate, the latter being extracted into the resulting aqueous phase discharged from area 506 via line 509. Following neutralization, aqueous HCl is introduced into the amination zone 506 via line 511 and under these conditions the unreacted aniline forms aniline hydrochloride, a water-soluble aniline salt, and is extracted into the resulting aqueous phase which is discharged via line 512 and comprises water, aniline hydrochloride and n-butanol. A slurry of p-nitroso-diphenyl-amine, n-butanol and water is then withdrawn from zone 506 via line 513 and may then be sent to separation and purification means for recovery of the p-nitroso-diphenylamine produced.

Because of the small proportion of residual organic phase in zone 506 following removal of the aqueous phase via line 512, zone 506 may be added with a suitable inert diluent, such as n-hexane, via line 506. 514 to facilitate handling of this phase during product recovery, and in this case this diluent is also present in line 513.

In carrying out the discontinuous type operation described above, it is necessary to provide in zone 506 means, for example a filter assembly, to collect the precipitated p-nitrosodiphenylamine produced and prevent its passage into the aqueous phase. to remove.

As an alternative to the succession of neutralization and acidification operations in zone 506 described above, said succession can be reversed in accordance with the implementation illustrated with reference to FIG. 4c.

Thus, following the amination phase in zone 506, water or an acid in line 511 is introduced into zone 506 and, under these conditions, the unreacted reactive amine is converted into a water-soluble salt and extracted into the resulting aqueous phase, the latter then being removed from area 506 via line 512 for further processing as discussed above. The organic phase remaining in zone 506 is then neutralized with an aqueous alkaline agent from line 507 with formation of separated organic and aqueous phases, the aqueous phase being removed via line 509 for further treatment as discussed above and the organic phase being removed via line 513 for further processing, the dying compositions in each case being the same as those illustrated above.

The implementations described above with reference to FIG. 4a-c and 5 differ from the implementation of the overall method of FIGS. 2a-c, in particular in that: 1) the total exit product of the etherification is sent to the amination without the need to first remove the unreacted p-nitrosophenol; 2) a system of additional neutralization and acidification stages following the amination is provided for recovery and recycling to the process of the unreacted aniline and p-nitrosophenol reactants. The implementations of FIGS. 4a-c, however, require that the conversion per etherification pass be of the order of 90% or more since larger proportions of unreacted accompanying p-nitrosophnol tend to enter. in undesirable side reactions during amination, with concomitant decreased yield of amination product. The implementations of FIGS. 4a-c and 5 are therefore only employed when such conversions by passing through etherification are carried out. As described above, the sparging phase whereby the equilibrium is shifted to the ether side, with sparging conditions suitable to effect substantially complete removal of water, is required in the practice of such implementations. work.

With reference to fig. 6, dry p-nitrosophenol, dry methanol and p-toluenesulfonic acid hydrate are added to the etherification zone 223, preferably as a mixture, via lines 221 and 222, in the preferable relative proportions of 10 to 30% p-nitrosophenol, 70 to 90% alcohol, and 0.25 to 10% acid, all on a molar basis. The addition of these materials can be made, if desired, as separate streams, although in this case some methanol will be required as a solvent for the p-nitrosophenol unless, alternatively, , the p-nor trosophenol is added in the solid state.

The etherification zone 223 is maintained at any suitable temperature within the range described herein, preferably on the order of about 15 to 70°C, under which conditions the p-nitrosophenol is reacted. with methanol to form p-nitrosophenylethyl ether. The reaction time in zone 223 is sufficient to practically reach etherification equilibrium, it is generally about 10 to 200 minutes.

The total output from etherification zone 223 is sent via line 224 to neutralization zone 226 along with an aqueous alkaline agent, for example an alkali metal hydroxide such as sodium hydroxide, from the line 227, suitable-and in a substantially exact amount-for neutralizing only the acid component of the output from line 224, which output comprises p-nitrosophenetole (the ether), p-nitrosophenol not reaction ; the reaction in zone 226 is carried out at any suitable temperature, advantageously at approximately 20-300° C., and is controlled as described above so as to neutralize only the acid catalyst, so as to retain the p-nitrosoph6nol in its initial form not reacted to recycle it as described below.

The output from zone 226 includes ether, unreacted reactants, water, and catalyst salt, and is sent to solvent exchange and distillation zone 228 via line 229. zone where it is distilled under suitable vacuum conditions in the presence of a solvent which has, vis-à-vis the p-nitrosophenol, a sufficiently weak solvent action to cause the precipitation of this p-nitrosophenol when it has replaced the alcohol-reactive solvent, but which then shows, with respect to the ether produced, a solvent power, sufficiently high to retain this ether in solution.

Examples of these solvents are hydrocarbons such as n-pentane, n-hexane, n-heptane, benzene, toluene and xylene; chlorinated hydrocarbons such as carbon tetrachloride, chloroform and methylene chloride, and esters such as ethyl acetate and butyl acetate. This solvent is preferably a liquid hydrocarbon, for example n-heptane, and it is introduced into zone 228 via line 230. Under the distillation conditions of zone 228, the water comprising the etherification water-and methanol is removed from the system, n-heptane is exchanged for methanol and unreacted p-nitrosophenol is precipitated for separation and recycle. Thus, in zone 228, the output from zone 226 is distilled under vacuum conditions for removal of ethanol and water as a distillate via line 232 and for removal of methanol and n -heptane as a fraction separated via line 231. Enough n-heptane is admitted via line 23Q to compensate for that lost via line 231.

If desired, zone 228 can be operated discontinuously in conjunction with a holding tank, the latter to receive output product from zone 226 with cyclic evacuation of said product to zone 228. In such an operation , the output liquid from zone 226 is first distilled in zone 228 to remove methanol and water as overhead, for example, via line 232. N-heptane is periodically adds as a make-up to the system from line 230. Upon removal of all the water via line 232, distillation is continued to remove the remainder of the methanol as an n-heptane- azeotrope. ethanol via line 232. In such a batch operation, line 231 is not necessarily used. As methanol is removed from the system and n-heptane is added, the solubility of the unreacted p-nitrosophenol in the distillation mixture decreases until almost all of the methanol is removed and replaced with n-heptane, substantially all of the unreacted p-nitrosophenol has precipitated, and the bottoms thus obtained comprise a paste of unreacted p-nitrosophenol and catalyst salt. in a solution of p-ni trosophenetole in n-heptane.

Either way, it is. that is, whether the operation in zone 228 is continuous or discontinuous, the total output product-a paste-is sent to zone 228, via line 233, to separation zone 234 which may be any suitable means for separating solid p-nitrosophenol for recycle to etherification zone 223. Thus, zone 234 may include a centrifugal separator system in which solid p-nitrosophenol is separated from residual liquid and disposed of in any suitable manner. , for example in the form of a paste with water from line 225. via line 236 to a. a water wash zone 237 in which the catalyst salt is washed away from the solid p-nitrosophenol and is discharged, together with water from line 235, via line 238. filtration as a remedial means in zone 234, the output from zone 228 may be discharged into a holding tank and fed in portions to a filtration apparatus which is cycled to collect a cake of p -nitrosophenol non reacts solid and then discharge this cake, preferably in the form of a paste with water from line 225, via line 236. Another possible operation of the filtration system may include two devices filtration units connected in parallel to line 233 and operable in cycles such that one operates to collect precipitated p-nitrosophenol while the other operates to remove previously collected p-nitrosophenol. The collected precipitate can be washed with water after removal of the filtrate from the filtration apparatus, the washings being discarded.

Regardless of the particular separation means employed in zone 234, wet p-nitrosophenol from line 239 is thermally dried under vacuum in zone 241, for example under a vacuum ranging from 10 to 60 mm/Hg at a temperature of 35 to 600 C, for sufficient time to distill substantially all of the water out of the solid p-nitrosophenol for disposal via line 242. Residual dry p-nitrosophenol is removed from area 241, either alone or mixed with dry methanol from line 243, and is recycled to zone 223 via lines 244 and 222.

The residual liquid from the repair of the p-nitrosophnol in zone 234 comprises an n-heptane solution of the ether produced and is evacuated via line 246 to the crystallization zone 247 maintained at a temperature low enough to cool the solution coming from line 246 in order to cause crystallization of the p-nitrosophenetole, i.e. ether, this cooling temperature being generally of the order of about -400 C. The cooling in the Zone 247 generally requires about 100 to 500 minutes although, of course, the actual time required will depend on the concentration of the solution and the cooling temperature employed.

Alternatively the solvent can be separated from the ether by conventional vacuum distillation. The p-nitrosophenetole crystals are removed from area 247 as a paste in n-heptane from line 250, if desired, via line 254 to area 256 from which the residual solvent-in in this case the n-heptane is vented via line 258 to storage, or for recycling to line 230 for reintroduction into the system. The dry crystals from area 256 are evacuated via line 257 to storage.

The mother liquor resulting from the crystallization in zone 247 and which contains a little p-nitrosophenetole not crystallized in n-heptane is evacuated from this zone 247 via line 248 to the distillation zone 251, the latter being maintained under vacuum distillation conditions to ensure that a substantial portion of the n-heptane from line 249 is sent as overhead via line 252 to n-heptane storage or to recycle via line 230. The bottoms product from zone 251 comprises a low n-heptane ether solution which is recycled to zone 247 via line 253.

With reference to fig. 7, p-nitrosophnol with methanol, toluene as the balance solvent, and an acid as the etherification catalyst, e.g., sulfuric acid, are sent together to the etherification zone 263, preferably in the form of mixed, via lines 261 and 262 and are added to this zone 263 in the preferred relative proportions described with reference to FIG. 6. The temperature, pressure and time conditions for etherification in zone 163 are the same as those described above with reference to zone 223 of FIG. 6 to effect acid-catalyzed etherification, in this case the etherification of p-nitrosophenol to form p-nitrosoanisole.

The total output from zone 263 includes ether, unreacted p-nitrosophnol, unreacted methanol, toluene, water, and acid catalyst, and is vented via line 264 to to neutralization zone 266 for neutralizing the acid catalyst with a suitable neutralizing agent, preferably an alkali metal hydroxide such as sodium hydroxide, from line 267.

The neutralization conditions in this zone 266 are the same as those carried out in the zone 226 of FIG. 6: It is important to add only enough alkaline agent to neutralize the acid. Output from area 266 includes p-nitrosoanisole, p-nitrosophenol no. reacts methanol, toluene, water and acid salt and is discharged via line 268 to distillation zone 269 which is a distillation to remove methanol and water from the system and replace the methanol with toluene, i.e. in solvent exchange, to cause precipitation of the unreacted p-nitrosophenol due to its low solubility in toluene, for separation and recycling to the etherification zone 263. Distillation zone 269 is maintained under vacuum distillation conditions to ensure removal of water, including water of etherification, and methanol as separate toluene azeotropes via the lines 271 and 272 respectively. Thus, as methanol is distilled from the system and replaced with toluene from line 273, the solubility of p-nitrosophenol in the distillation mixture decreases and substantially complete precipitation occurs. Supplemental toluene is added via line 273 in an amount such that it compensates for that lost as a constituent of the two azeo, topic fractions.

If desired, the output from line 268 can be sent to a holding tank for delivery of the liquid to zone 269 for portion distillation. In this case, the liquid in zone 269 is first distilled to remove a metanol-toluene azeotrope via line 272, and the distillation is continued to remove water as a toluene-water azeotrope by line 272, line 271 not being used in this discontinuous operation.

Bottoms from zone 269 include catalyst salt and unreacted p-nitrosophenol slurry in the toluene-ether solution, they are discharged via line 274 to separation zone 276 which, like zone 234 of fig. 6, can be any suitable means for separating the solid p-nitrosophenol from the paste. Thus, when a centrifugal separator is used in zone 276, the p-nitroso phenol separated in this zone 276 is discharged via line 277 to the washing zone 278 in any suitable way, for example in the form a slurry with water from line 275, and is washed therein with water from line 279 to remove catalyst salt, i.e. sodium sulfate salts, via line 281 at the same time as the washing water. If area 276 is a filtration system, the collected filter cake can be removed and transferred to area 278 in the same manner as described with reference to FIG. 6 regarding the removal of solid p-nitrosophenol from a system in area 234 and sending it to area 237.

The moist p-nitrosophenol in zone 278 is then sent to drying zone 282 via line 283 and is heat treated there at a certain temperature and under vacuum for the repair of water in the form of vapor via line 283. 284.

Dry p-nitrosophenol is sent from area 282, mixed with toluene and/or methanol, as desired. from line 287, and the formed mixture is recycled to etherification zone 263 via line 286.

The residual liquid from zone 276 comprises a toluene solution of the product ether and can be sent via lines 288 and 289 directly to the crystallization zone 291 for cooling and crystallization of the product ether for recovery of this ether under form of crystals. Similar to what has been illustrated with reference to areas 247 and 251 of FIG. 6 and the streams associated therewith, the residual solution of ether in toluene can be evacuated from zone 291, if desired, for distillation in order to remove the toluene and ensure the recycling of the residual toluene-ether solution to the crystallization zone.

However, the last traces of toluene are difficult to remove crystals in area 291 and therefore it is preferable to first pass the liquid in line 288, via line 290, to area 291. distillation 292 in which the toluene is distilled in the form of an overhead distillate via line 285 to ensure its replacement by an appropriate solvent which is more volatile than toluene and which can be easily removed from the crystals formed in zone 291 and dried in drying zone 294. A solvent with a lower boiling point than toluene, for example an alkane such as n-pentane, is advantageously used for this purpose and is added to the bottoms product of zone 292 via line 295 as a replacement for the toluene distilled overhead. Although the bottoms product from zone 292 contains some toluene, the molar fraction of it in the solution in line 289 is so low that it does not pose a problem in terms of its removal. crystals in zone 291. The n-pentanep-nitrosoanisole solution is sent, via line 289, to crystallization zone 291 and is cooled there under conditions suitable for crystallizing the ether; a slurry of n-pentane crystals from area 291 is removed via line 293 to desiccator 294 and treated there to remove the n-pentane via line 299 for storage or recycling to area 292 and to yield dry crystals of p-nitrosoanisole for disposal to storage via line 301.

The mother liquor from area 291 comprises n-pentane with a small amount of toluene and some uncrystallized p-nitrosoanisole; it is removed via line 297 to distillation zone 302 where a major proportion of the n-pentane is distilled as overhead via line 303 for storage or recycling to the system via line 295. Distillation bottoms from zone 302 are recycled to zone 291 via line 304.

With reference to fig. 8, a paste of p-nitrosophenol, a primary or secondary alcohol and an acid, all in the preferred relative proportions identical to those indicated above with reference to FIGS. 6 and 7, are introduced via line 305 into etherification zone 306 which is maintained under etherification conditions identical to those described herein with reference to FIGS. 6 and 7, conditions under which etherification takes place to form the corresponding p-nitrosophenyl ether.

The maximum etherification reaction equilibrium that ordinarily takes place in zone 306 is on the order of 50-55% towards the ether side. However, by removal of the water of etherification from the ether-forming reaction zone during the ether-forming reaction, the equilibrium is shifted to the ether side with concurrent conversion by increased passage of p -nitroso phenol to ether. Accordingly, zone 306 is maintained under vacuum fractional distillation conditions also suitable for etherification such that the water of etherification is distilled therefrom, during the ether-forming reaction, in the form of etherification. a constituent of a reactive water-alcohol overhead distillate, sometimes an alcohol-water azeotrope, evacuated via line 307. Suitable vacuum fractional distillation conditions in area 306 are, for example, of the order of about 20 to 50 mm/Hg at about 20 to 500 C.

The water-alcohol from line 307 can be sent via line 308 for use outside the process but is preferably sent to zone 309 via line 310, zone in which the alcohol component is separated by any separation means. appropriate and discharged via line 311 for recycling to the etherification zone via line 305, the water thus separated being discharged via line 312.

The residual output from zone 306 contains p-nitrosophenyl ether obtained at a conversion by passage of p-nitrosophenol to ether exceeding 55%, for example about 60-65%, and is discharged via lines 313 and 314 to any suitable ether recovery system to recover the ether produced.

However, it is advantageous to send the total output from line 313 via line 315 to crystallization zone 316 and maintain it there under cooling conditions for the formation of p-nitrosophenyl ether crystals. , as described with reference to the crystallization of ether in the process of FIGS. 6 and 7.

Output toat1 is sent from zone 316 via line 317 to zone 318 which includes any suitable means to separate the crystals from line 317 from their mother liquor, such as a filtration system or centrifugation.

Wet crystals of alcohol from zone 318 are discharged via line 319 to drying distillation zone 321 and dried there under conditions to separate the alcohol for disposal via line 322 for recycling, if desired, via line 305, and the ether, not crystallized in zone 316, evacuated via line 323, for recycling, if desired, to zone 316 via line 314. The mother liquor from the zone 316 is evacuated from zone 318 via line 320.

Neutralization of acid and unreacted p-nitrosophenol in the etherification output from line 313 can be omitted when the conversion of p-nitrosophenol to ether is order of 60 to 65 per cent, because of the correspondingly smaller proportion of p-nitrosophenol not reacting in the output product of the etherification which, although it crystallizes with the ether produced in the form of contaminant, can be separated from it to eliminate the neutralization phase before crystallization. However, if desired, and if the reactive alcohol is not miscible with water, the output from line 313 can be neutralized with an aqueous alkaline agent to convert the p-nitrosophenol not between in reaction therein in the corresponding phenolate, operation followed. separating an organic phase free of p-ni trosophenol and cooling said organic phase to crystallize the ether produced therefrom; and if said reactive alcohol is absolutely immiscible with water, the output product from line 313 may first be subjected to a solvent exchange phase as illustrated with reference to FIGS. 6 and 7, phase followed by the crystallization of the ether crystals from the solvent phase thus obtained.

With reference to fig. 9, a paste of p-nitrosophenol in a primary or secondary alcohol such as methanol or isopropanol, and an acid such as sulfuric acid are introduced, preferably as a mixture, via line 410 into zone etherification unit 411 maintained under conditions for the etherification of p-nitro sophenol with alcohol generally at a temperature in the range of 0 to 150°C, for any suitable period of time, e.g. 10 to 200 minutes. The molar ratio of alcohol to p-nitrosophenol added to zone 411 is generally in the range of 1:1 to 100:1, the resulting reaction mixture generally containing an acid catalyst/p-nitrosophenol molar ratio of about 0.01:1 to 0.2:1.

The etherification usually taking place in zone 411, governed by the equal range noted above, provides maximum conversion on the order of 50 to 55 per pass. The reaction mixture in zone 411 may be subjected to vacuum distillation to remove water of etherification to shift the equilibrium to the ether side with improved conversion per pass.

However, the normal technique of vacuum distillation for this purpose is in most cases undesirable, particularly in that it is excessively time-consuming, labor-intensive and material-intensive and comes with undesirable side reactions and lowered ether yield. It is therefore more advantageous to employ a spray phase instead of the normal vacuum distillation to remove the water of etherification. Consequently, as shown in fig. 9, a suitable dry spray medium is sent via line 412 up and through zone 411 in contact with the etherification reaction mixture in this zone, and is discharged via line 413 at the same time. than the etherification water, part of which is entrained in the spray gas but the majority of which is present in the form of saturated vapor. As sparging continues, the water of etherification is removed via line 413 and an equilibrium shift to the ether side occurs. Generally, the liquid reactors coming from the line 410 introduced into an upper part of the zone 411 descend there by gravitation for the removal of all of the reaction titmouse thus obtained via the line 414, in countercurrent flow relation. with the sprinkling agent, so that the equilibrium shift etherification has taken place at the time the output product is withdrawn via this line 414. The sprinkling agent and the water withdrawn via the 413 can be evacuated for use outside the system via line 416 or else can be recycled via line 417 to the drying zone 418 for separation of the water from the spray agent, the former being removed via line 419 and the second discharged via line 421 either for storage outside the system via line 422 or for recycling to line 412 via line 423. If the spray agent from line 423 is a alcohol identical to the reactive alcohol in zone 411, it can, if desired, be recycled in part or in whole to zone 411 via line 410.

The etherification output, withdrawn via line 414, includes some reactants, unreacted p-nitroso phenol and alcohol, acid and product p-nitrosophenyl ether, e.g. p-nitrosophenyl ethyl ether, and is sent as a solution to crystallization zone 424 where it is cooled to cause crystals to form and separate from the product p-nitrosophenyl ether, the output product of the zone 424 thus obtained, and which contains the crystals, being evacuated via the pipe 426 to the separation zone 427 which comprises any suitable means for separating the crystals from the mother liquor, for example by filtration or centrifugation. Residual liquid from this area 427 is removed via line 428 and includes unreacted p-nitro sophenol and alcohol reactants which can be recycled to the system via lines 428 and 410.

The alcohol-wet ether crystals are removed from the separation zone 427 via lines 429 and 431 for recovery or further reaction of the ether produced, or via lines 429 and 432 to the distillation zone 433 for separation of the alcohol as a distillate fraction removed via line 434, residual ether bottoms product being removed via line 436.

With reference to fig. 10, the etherification reagents are sent via line 410' to the etherification zone 436 maintained under conditions of temperature and time suitable for the etherification of the p-nitrosophenol with the alcohol to form the ether. corresponding p-nitro sophenyl, as described with reference to the etherification in area 411 of FIG. 9. However, etherification in zone 436 controlled by the equilibrium characteristics described above gives no more than about 50-55% conversion per passage of nitroso phenol to ether. The total output is sent from zone 436, via line 437, to distillation and equilibrium displacement zone 438 also maintained at conditions suitable for the etherification reaction of zone 436. Zone 438 comprises a vacuum-spray distillation phase in which, as illustrated with reference to FIG. 9, a dry sparge is introduced and passed through the etherification reaction mixture via line 439, this gaseous or vapor sparge, along with the water, being removed from zone 438 via line 441. In this manner etherification has been effected at a conversion per pass approaching the maximum allowable equilibrium value in zone 436 and etherification is then substantially complete in zone 438 by removal of etherification water accompanied by equilibrium shift and high conversion per pass. By carrying out the etherification initially in one time and ending it in another time, with sprinkling as illustrated, the water of etherification accumulates in this second time and requires a lesser amount of sprinkling agent for its removal. than when the etherification and spraying phases are carried out in a single container. In addition, in the second stage, the reactive p-nitrosophenol in suspension introduced in the first stage is passed into solution, to replace that which reacts in the first stage, to ensure the reaction of a solution instead of a paste. in the second time. This is particularly important when carrying out the etherification-spray under countercurrent flow conditions in a packed vessel. The spray agent and the water in line 441 can be dried and recycled to the system as illustrated with reference to the stream of spray agent-water in line 413 of FIG. 9, or they can be evacuated to points outside the system, as desired. The etherification output product evacuated from zone 438 via line 442 can be sent for product recovery as illustrated with reference to zones 424 and 423 of FIG. 9.

CLAIMS I. Process for the manufacture of a p-nitroso phenyl ether, characterized in that p-nitrosophenol is reacted with a primary or secondary alcohol in the presence of an acid and at a temperature comprised in the range from 0 to 150 C.

II. Use of the p-nitrosophenyl ether resulting from the process according to claim 1 to produce a p-nitroso-N-substituted niline, characterized in that the p-nitrosophenyl ether is reacted with an aliphatic or phenyl primary amine in presence of an acid and at a temperature of 0 to 160 C.

SUB-CLAIMS 1. Process according to claim 1, characterized in that the water of etherification is removed by sprinkling the reaction mixture with a substantially anhydrous sprinkling agent.

2. Method according to sub-claim 1, characterized in that 1'on employs, as sprinkling agent, the same alcohol as that used to react with the nitroso phenol, preferably n-butanol.

3. Process according to claim 1, characterized in that the water of etherification is removed by fractional distillation.

4. Process according to claim 1, characterized in that a water-miscible alcohol is employed and in that, after completion of the etherification, the acid catalyst is neutralized with an aqueous alkali, preferably a metal hydroxide. alkaline, in that the p-nitrosophenyl ether is separated from the unreacted p-nitrosophenol by exchange of the reactant-solvent alcohol with a solvent having a high solvent power for the p-nitrosophenyl ether but low for the p-nitrosophenol, and in that the separated p-nitrosophenol is recycled.

5. Process according to sub-claim 4, characterized in that the exchange solvent is incorporated into the etherification reaction mixture, in that the reagent-solvent alcohol is removed from this mixture after the etherification, by distillation, in such a way as to cause the precipitation of the p-nitrosophenol which does not enter into reaction, and in that the exchange solvent in the filtrate thus obtained is replaced with ether and the solvent of exchange with a more volatile solvent so as to aid the subsequent crystallization of the ether.

6. Process according to claim 1, characterized in that a water-immiscible alcohol is used and in that the unreacted nitrosophenol present in the reaction mixture is neutralized with an aqueous alkali, preferably an alkali metal hydroxide, in that the nitrosophenolate thus formed is separated, in that the nitrosophenolate is acidified to regenerate the nitrosophenol and in that the nitrosophenol thus produced is recycled to the etherification phase.

7. Process according to claim 1 and sub-claim 2, characterized in that the etherification reaction mixture is sprinkled to obtain a conversion per passage of the nitrosophenol of at least 90%.

8. Process according to sub-claim 7, characterized in that the etherification is carried out in two stages, with sprinkling in the second stage.

9. Process according to claim, characterized in that the alcohol/p-nitrosophenol molar ratio is 1: 1 and 200: 1, the acid/p-nitrosophenol molar ratio is 0.005: 1 and 0.2: 1, the temperature is 15 to 700 C, and the reaction time is 10 to 200 minutes in the etherification phase.

10. Use according to claim II, characterized in that 1'on employs aniline as amine, so <

**WARNUNG** Ende DESC Feld konnte Anfang CLMS uberlappen**.

Claims (11)

**WARNUNG** Anfang CLMS Feld konnte Ende DESC uberlappen **. With reference to fig. 10, the etherification reagents are sent via line 410' to the etherification zone 436 maintained under conditions of temperature and time suitable for the etherification of the p-nitrosophenol with the alcohol to form the ether. corresponding p-nitro sophenyl, as described with reference to the etherification in area 411 of FIG. 9. However, etherification in zone 436 controlled by the equilibrium characteristics described above gives no more than about 50-55% conversion per passage of nitroso phenol to ether. The total output is sent from zone 436, via line 437, to distillation and equilibrium displacement zone 438 also maintained at conditions suitable for the etherification reaction of zone 436. Zone 438 comprises a vacuum-spray distillation phase in which, as illustrated with reference to FIG. 9, a dry sparge is introduced and passed through the etherification reaction mixture via line 439, this gaseous or vapor sparge, along with the water, being removed from zone 438 via line 441. In this manner etherification has been effected at a conversion per pass approaching the maximum allowable equilibrium value in zone 436 and etherification is then substantially complete in zone 438 by removal of etherification water accompanied by equilibrium shift and high conversion per pass. By carrying out the etherification initially in one time and ending it in another time, with sprinkling as illustrated, the water of etherification accumulates in this second time and requires a lesser amount of sprinkling agent for its removal. than when the etherification and spraying phases are carried out in a single container. In addition, in the second stage, the reactive p-nitrosophenol in suspension introduced in the first stage is passed into solution, to replace that which reacts in the first stage, to ensure the reaction of a solution instead of a paste. in the second time. This is particularly important when carrying out the etherification-spray under countercurrent flow conditions in a packed vessel. The spray agent and the water in line 441 can be dried and recycled to the system as illustrated with reference to the stream of spray agent-water in line 413 of FIG. 9, or they can be evacuated to points outside the system, as desired. The etherification output product evacuated from zone 438 via line 442 can be sent for product recovery as illustrated with reference to zones 424 and 423 of FIG. 9. CLAIMS I. Process for the manufacture of a p-nitroso phenyl ether, characterized in that p-nitrosophenol is reacted with a primary or secondary alcohol in the presence of an acid and at a temperature comprised in the range from 0 to 150 C. II. Use of the p-nitrosophenyl ether resulting from the process according to claim 1 to produce a p-nitroso-N-substituted niline, characterized in that the p-nitrosophenyl ether is reacted with an aliphatic or phenyl primary amine in presence of an acid and at a temperature of 0 to 160 C. SUB-CLAIMS 1. Process according to claim 1, characterized in that the water of etherification is removed by sprinkling the reaction mixture with a substantially anhydrous sprinkling agent. 2. Method according to sub-claim 1, characterized in that 1'on employs, as sprinkling agent, the same alcohol as that used to react with the nitroso phenol, preferably n-butanol. 3. Process according to claim 1, characterized in that the water of etherification is removed by fractional distillation. 4. Process according to claim 1, characterized in that a water-miscible alcohol is employed and in that, after completion of the etherification, the acid catalyst is neutralized with an aqueous alkali, preferably a metal hydroxide. alkaline, in that the p-nitrosophenyl ether is separated from the unreacted p-nitrosophenol by exchange of the reactant-solvent alcohol with a solvent having a high solvent power for the p-nitrosophenyl ether but low for the p-nitrosophenol, and in that the separated p-nitrosophenol is recycled. 5. Process according to sub-claim 4, characterized in that the exchange solvent is incorporated into the etherification reaction mixture, in that the reagent-solvent alcohol is removed from this mixture after the etherification, by distillation, in such a way as to cause the precipitation of the p-nitrosophenol which does not enter into reaction, and in that the exchange solvent in the filtrate thus obtained is replaced with ether and the solvent of exchange with a more volatile solvent so as to aid the subsequent crystallization of the ether. 6. Process according to claim 1, characterized in that a water-immiscible alcohol is used and in that the unreacted nitrosophenol present in the reaction mixture is neutralized with an aqueous alkali, preferably an alkali metal hydroxide, in that the nitrosophenolate thus formed is separated, in that the nitrosophenolate is acidified to regenerate the nitrosophenol and in that the nitrosophenol thus produced is recycled to the etherification phase. 7. Process according to claim 1 and sub-claim 2, characterized in that the etherification reaction mixture is sprinkled to obtain a conversion per passage of the nitrosophenol of at least 90%. 8. Process according to sub-claim 7, characterized in that the etherification is carried out in two stages, with sprinkling in the second stage. 9. Process according to claim, characterized in that the alcohol/p-nitrosophenol molar ratio is 1: 1 and 200: 1, the acid/p-nitrosophenol molar ratio is 0.005: 1 and 0.2: 1, the temperature is 15 to 700 C, and the reaction time is 10 to 200 minutes in the etherification phase. 10. Use according to claim II, characterized in that aniline is used as the amine, whereby <BR> p-nitrosodiphenylamine is obtained. 11. Use according to claim II, characterized in that the amine/acid molar ratio is from 5:1 to 20:1, the amine/ether molar ratio is from 0.5:1 to 2:1, the temperature is from 15 to 1000 C, and the reaction time is from 1 minute to 48 hours. **WARNUNG** Ende DESC Feld konnte Anfang CLMS uberlappen**. **WARNUNG** Anfang CLMS Feld konnte Ende DESC uberlappen **. BR> which gives p-nitrosodiphenylamine. 11. Use according to claim II, characterized in that the amine/acid molar ratio is from 5:1 to 20:1, the amine/ether molar ratio is from 0.5:1 to 2:1, the temperature is from 15 to 1000 C, and the reaction time is from 1 minute to 48 hours.