DE2653641C3 - Process for the preparation of 1,3-diaryltriazene - Google Patents

Description

1,3-Diaryl triazenes (also called »Diazoaminoarylverbin · fertilize «) can by heating, z. Am In the presence of a Friedel-Crafts catalyst, the rearrangement can be caused to form aromatic aminoazo compounds. From the latter connections is obtained by reduction with hydrogen aromatic diamines, which in turn are used as starting materials bonds for the synthesis of z. B, polymers or antioxidants are suitable.

According to US-PS 2894942 aromatic Aminoazo compounds prepared by

ίο an inorganic nitrite in a mixture of an excess of a primary aryl monoamine, a mineral acid and a Friedel-Crafts catalyst at a temperature of 0 to 50 ⁰ C (preferably 20 to 30 ⁰ Q and then the approach to about 40 to 75 ° C (preferably 45 to 55 ° C) heated Part of the amine is diazotized and the diazonium salt formed couples with unreacted amine to form the diazoaminoaryl compound, which under the combined thermal-catalytic action of the aminoazo- connection surrounded A disadvantage of this method, which is noticeable in large-scale operation power consists in the fact that the salt formed as a by-product during the diazotization (e.g. sodium chloride) must be separated and disposed of.

From time to time within at least a century there have been publications showing the Describe the diazotization of primary aromatic amines with the aid of certain nitrogen oxides. Semolina reported, for example, in 1862 (Ann. 121, No. 3, Pages 257 to 280) on a synthesis of diazoaminobenzene, in which a so-called »weak stream of nitrous acid ”in a cold, alcoholic aniline solution until all of the aniline is used up is initiated. Griess used the formula »NO3« for nitrous acid, without describing the composition or origin of its diazotization agent.

From US-PS 26 22 078 it is known to diazotize aminoaromatic sulfonic acids Carry out diazonium compounds in water / ketone mixtures. Although, according to this patent specification, a "nitrous gas" (described as N ₂ O ₃ or a mixture of NO and NO2 with a composition approximately corresponding to N2O3) is suitable for the reaction suitable, the gas is converted into a mixture of at 20 ° C Acetone or butanone, water and nitric acid introduced and the amino compound is the one Temperature of less than 35 ° C maintained mixture is also incorporated according to the mentioned

so patent specification of the entire amine for the synthesis of the Diazonium compound is consumed and the latter is not subjected to any coupling.

Love joy et al. describe in J. Chem. Soc (A) (1968), Pages 2325 to 2328 the manufacture of a Diazoniumni trits by converting a primary aromatic Amine with liquid, undissociated nitrous oxide at -85 "C in an organic solvent, whereby at times a small amount of the diazoamino compound is isolated, however, the authors describe neither the effect of gaseous nitrogen trioxide on the amines nor the conditions which are necessary for the Synthesis of a diazoamino compound would be required as the main product The diazotization of aromatic amines by means of

es N] Oj-GaS in the absence of water (solvent) and the coupling of the resulting diazo compound with phenols or naphthols, which also takes place in the absence of water, is disclosed in the published

Japanese Patent Application 15631/61 (Sep. 7, 1961).

Primary aromatic aroins have also already been made using pure nitrogen tetroxide in the presence of Solvents diazotized O. N. Witt, Tagbi. Natf.-Vers. s Baden-Baden 1879, page 194 (Chem, Zentr, 1880, II, Page 226) describes the production of benzene diazonium nitrate by converting pure, anhydrous Nitrogen tetroxide with aniline in anhydrous benzene solution; B. Houston et al., J. Am. Chem. Soc. 47 (1925), Pages 3011 to 3018 presented a diazoaminobenzene derivative and the corresponding diazonium nitrate Effect of pure, anhydrous nitrogen tetroxide on o-, m- and p-nitroaniline in anhydrous benzene solution.

Although the hot gases formed during ammonia oxidation were previously absorbed in inorganic liquids - for example for the production of ammonium nitrite (US Pat. No. 2,797,144 and US Pat objections to the association of a primary aromatic monoamine (that is, a strong reducing agent) with the product obtained by oxidation of ammonia hot gas, since the controllability of the reactions between derarti- v> gen substances is doubtful According to the invention has been surprisingly found that the reaction between the through Ammonia oxidation obtained hot gas and an aromatic monoamine can be carried out in a smooth and controllable manner

The subject matter of the invention is reflected in the claims

In the inventive method, ammonia gas and a diluted molecule "tn oxygen-containing forming gas (yorzugsweise air) are passed at elevated temperature over a catalyst whereby the NH ₃ is oxidized to nitrogen oxide (NO); the gas obtained, which is a mixture of nitrogen oxide, oxygen, water vapor and an inert diluent (e.g. nitrogen) is cooled, the nitrogen oxide being completely or (preferably) partially _{oxidized to nitrogen dioxide (NO 2} ) and a gas mixture being obtained, which nitrogen dioxide (preferably also nitrogen oxide), the diluent, water vapor and - depending on the respective special conditions - possibly some residual oxygen

The oxidation of ammonia and then the nitrogen oxide obtained by air at elevated temperature with the formation of _{gas mixtures containing a "nitrogen oxide component" NO x} is dealt with comprehensively in the literature. A platinum or platinum alloy catalyst and temperatures in the range of about 800 to 950 ^° C. is used. The work is carried out at pressures from about atmospheric pressure up to an overpressure of 8.16 atm. Air enriched with oxygen can also be used. The ammonia content of the ammonia / air mixture is generally in the range from about 11 to 13 mol%, the oxygen / ammonia w molar ratio in the range from about 1.3: 1 to 1.7: 1. For further details see Mellor's Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. VIII, Erg. II, Chap. XXIX or Riegel's Handbook of Industrial Chemistry, 7th edition, Van Nostrand (1974), pages 94 to 98.

The oxidation of nitrogen oxide takes place at a lower temperature than the oxidation of ammonia, for example in the range of about 100 to 500 ⁰ C, because the rate of oxidation at lower temperatures and higher pressures is higher, the NO ₂ content of the Stickstoffoxidkomponente representing a MAQ for the oxidation state of Stickstoffoxidkomponente, by suitable choice of pressure, temperature, and the contact time of the gases in the NO oxidizer can be varied; the NOz content of the nitrogen oxide component increases with the duration of the contact. The contact time required to achieve a desired proportion of NOr can be determined from the known oxidation rates at various temperatures and pressures.

The content of the nitrogen oxide component in the gas mixture produced by air oxidation of nitrogen oxide is generally about 10 to 12 mol% and depends on the oxygen / ammonia molar ratio and the yield. Higher oxygen / ammonia ratios and yields lead to higher NO _x concentrationsa

Theoretically, up to about 17% NO can be achieved. A range of about 1 to 20 Moi-% NO _x can be achieved, for example, by dilution or removal of water vapor; Mixtures at such concentrations can be used in the diazotization / coupling stage. Mixtures with higher ΝΟχ-οη concentrations (e.g., up to about 30 mol%) can be achieved by combining the 1 to 20 mol% mixtures with more concentrated mixtures; Such mixtures are also suitable for the diazotization / coupling stage. However, NO * concentrations greater than about 12 mole percent are not preferred because of the added cost of attaining them and the loss of the beneficial effects of dilution on reaction control or the removal of water vapor from this mixture does not appear to achieve any advantage, which is why the aforementioned range of 10 to 12 mol% is preferably wild.

The NOj component can _{consist exclusively of NO 3} , but is preferably a combination of NO2 and NO. When NO _{consists only of NO 2} (ie, when χ 2 ), the 1,3-diaryltria tends to be yield in the subsequent diazotiemng / coupling due to

(1) a competing nitration reaction which in the case of aniline e.g. B. p- and o-nitroaniline results and

(2) a rearrangement of the triazene to the aminoazo compound catalyzed by the nitric acid formed as a by-product

is decreased. Although the nitro and aminoazo products can also be used, since they can be reduced to diamines, preferably as high a proportion of the monoamine as possible is converted into the triazene in the diazotization / coupling stage, which is why a NO _x with x <2 (ie a not nitrogen oxide consisting only of NOj) is preferred. By suppressing the formation of the aminoazo compounds during the diazotization / coupling as far as possible, the probability of the formation of by-products, which could subsequently pose problems, is reduced

The value for χ in NO is at least about 1.1, preferably at least about 13 · If the NO2 proportion of the mixture decreases, more nitrogen oxide remains

unconsumed, resulting in the triazene result has a low conversion at very low proportions NO2 excessive amounts have to be handled by unreacted nitric oxide, χ has preferably a value of at most about 1.7, so that there is no increased danger that rearrangements and nitrations or . Or oxidations take place, which then, as mentioned, prove to be disruptive. With regard to a good utilization of the nitrogen oxide and the greatest possible suppression of side reactions, a NO _{x is} particularly preferred in which χ in the vicinity of about 1.5 (equimolar NC ^ / NO mixtures), for example in the range of about 1, 4 to 1.6

The gas mixture obtained in the ammonia oxidation can be mixed with the monoamine in unchanged form to be brought into contact; this is the preferred mode of operation. A separation of water vapor from the reaction mixture before it comes into contact with the monoamine is of no advantage, although such a procedure is within the scope of the invention Frame lies

_{The nitrogen oxide component NO x} used in the diazotization / coupling reaction according to the invention is, as mentioned, in diluted form. The diazotization / coupling gas of the process according to the invention differs as such clearly from the pure N2O3 and N ₂ O * used in conventional diazotizations. The use of the dilute gas mixtures not only has the advantage that the diazotization gas is more readily available, but also ensures a smoother, more easily controllable conversion and therefore a reduction in the risk of yield losses caused by an uncontrolled reaction at the gas / liquid interface . Also in contrast to the conventional nitrite / acid diazotization method, no salt by-products are formed in the process according to the invention, which require complex separation processes.

In the method according to the invention, the temperature of the NOx-containing gas mixture immediately before it comes into contact with the monoamine (preferably aniline) is preferably in the range from about 25 to 35O ⁰ C, in particular from 110 to 275 ⁰ C. If the mixture, which corresponds to the normal case, containing water vapor, a gas temperature of at least about 110 ° C prevents condensation of water vapor from the gas and the associated formation of nitric acid, which catalyses the rearrangement of the 13-Diaryltriazens to aminoazo Above takes about 35O ⁰ C, the oxidative degradation of the monoamines place at at such temperatures it becomes more difficult to maintain higher oxidation states of the NO due to the increased rate of decomposition of nitrogen dioxide to nitrogen oxide and oxygen. Temperatures above about 275 ° C. are not preferred if the work is to be carried out with the exclusion of oxygen; Another reason for this is that expensive cooling measures have to be taken in order to keep the amine in the required temperature range, as will be explained in more detail below. In the process according to the invention, the monoamine for diazotization is advantageously brought into contact with a considerably hotter gas than was used in the conventional methods.

The diazotienip.ijs / coupling temperature or the Temperature at which the monoamine during the Contacts with the Stickstoffoxidkomponente NO _x containing gas mixture is maintained is in the range of about 25 to 9O ⁰ C temperatures above about 90 ⁰ C are not used because of the instability of the triazene and therefore feared yield losses The applied in a particular case temperature depends on various Factors. First, the temperature of the amine increases when it comes into contact with the hot NO _r gas mixture the heat of reaction and the heat transferred from the hot gas to the amine. It is therefore advisable to when the reaction temperature is in the vicinity of the temperature which results from the aforementioned exothermic and heat transfer and which can be easily maintained by moderate cooling (e.g. water cooling)

The reaction temperature can also take into account the solubility of the triazene and the consumed Amine amount can be selected. If a homogeneous If product is desired, it may be beneficial in the case of to work at a temperature at which the triazene at The degree of consumption or conversion of the process is soluble in the amine. 1,3-Diphenyltriazene, for example, has sufficient solubility at 50 to 55 ° C in aniline, that the product is homogeneous at the temperatures mentioned if about 20 to 40% of the Aniline were consumed. If more than 40% is used, higher temperatures are required for the Homogeneity required. In the diazotization / coupling Treatment of aniline is therefore a temperature of about 50 to 55 ⁰ C with consumed proportions up to about 40% particularly preferred, while higher temperatures with higher consumed proportions (z. B. with consumed proportions of more than about 40% temperatures up to to about 90 ° C) are particularly preferred.

Low temperatures such as about 25 ° C can be used in the diazotization / coupling reaction will; In the case of aniline, the homogeneity is still at this temperature with a consumed portion of 20% achievable. With regard to all factors to be considered, ie, the yield, the ease of maintenance of the temperature and the homogeneity of the product, the temperature range of about 40 to 6O ⁰ C is preferable

The diazotization / coupling process proceeds satisfactorily at atmospheric pressure, although one also does can apply increased pressures. In the latter case one usually works at those pressures which are soft nitric oxide oxidation are used, for example at pressures up to about 8.4 kp / cm ² .

In the process according to the invention, the NOr-containing gas mixture is mixed with an excess of the Mcnoamin brought into contact with it the initially formed diazonium salt (nitrite or nitrate) immediately with non-um set monoamine to a 1,3-diaryltriazene can couple. "Excess" monoamine means that there is always unused or unreacted monoamine is present; at least about 5% (preferably at least about 40%) of the Monoamins remain in the unconverted form. If the contact between NO _x and the reaction mixture is broken at a point in time when at least about 5% of the monoamine remains unconsumed, the enrichment can begin VGi; Avoid uncoupled diazonium nitrate in the reaction mixture.

The monoamine is made to react in the liquid phase. In the case of monoamines, which under

the reaction conditions are liquid, no solvent or diluent is required. For economic reasons For reasons, the monoamines are preferably used without the use of a solvent or diluent If the monoamine is solid under the reaction conditions, you can use a solvent use for it; Examples of suitable solvents are aromatic hydrocarbons, such as benzene or xylene and aliphatic halogenated hydrocarbons such as carbon tetrachloride or methylene to dichloride. The simultaneous presence of a as a solvent or diluent liquid (such as water) and a liquid monoamine implementation is not affected.

The reaction mixture should have a sufficient ii Liquid quantity include that with the resulting solid triazene a stirrable slurry or Suspension or solution is formed. Others-

fii 1j:: rr: j r Jl j

f-ii- 1

IOII3 ch

J ... "l. j "

uuit.it uu

Even if there is an excess of monoamine, the reaction mixture takes place so slowly that the Diazonium nitrate due to a reaction between the gas and the triazene on the surface of the solid Triazene can accumulate. Therefore, in the case of an unused monoamine content of only 5% To maintain stirrability an additional solvent is used if higher proportions of Unused monoamine are present, the required flowability of the reaction mixture with pure monoamine by using higher reaction temperatures. The conversion product preferably represents a homogeneous liquid; if pure monoamine is used, it will be sufficient The unused remaining portion is therefore sufficient to act as a solvent for the triazene.

Regardless of whether you are using pure, dissolved or diluted monoamine, you interrupt it Contact between the NOr-containing gas and the Reaction mixture always preferably at a point in time at which at least about 40% by weight (in particular at least about 60% by weight) of the monoamine remain unused. The triazene yield drops due to a rearrangement abruptly when the unused monoamine content has a value of about 40% even with a reduction in the unused monoamine content below about 60% there is a noticeable loss of yield. The proportion of the unconsumed monoamine is preferred no higher than about 85% to allow handling and reconditioning of excessively high volumes from low Triazenkonzentratioiiii-en containing materials avoided will. When the process is carried out semi-continuously, the NOx-containing gas becomes the monoamine incorporated and the addition stopped when the predetermined monoamine consumption has been reached (which can be determined by analyzing the reaction mixture). With a continuous process the product stream is separated from the gas stream when the predetermined monoamine consumption - like can be determined by analyzing the product flow - has been achieved

The agitating the reaction mixture has no detectable influence on the course of the reaction as such, but calls for the distribution of the gas hn monoamine and the good contact between the gas and the liquid phase.

The inventive method is suitable for. Diazotiertmg / Knpphmg of unsubstuated primary aromatic monoamines, such as aniline or α- or 0-naphthylamine, and of primary aromatic monoamines with substituents inert to NO, e.g. B. halogen atoms, nitro groups or alkyl, haloalkyl or alkoxy radicals. The alkyl, haloalkyl and alkoxy substituents preferably have from 1 to 4 carbon atoms. Examples of suitable substituted monoamines are o- and m-toluidine, 23-, 2,5-, 2,6- and 3,5-dimethylaniline, trifluoromethylaniline, o- and m-chloro-, bromo- and -fluoroaniline and the Nitroanilines.

The accumulation of aromatic diazonium nitrate at any point in the reaction system is in the The method according to the invention is undesirable because it can create a risk of explosion. The excess monoamine contained in the reaction mixture makes it possible that the initially formed Diazonium nitrate soiun with the monoamine for

tion of uncoupled diazonium nitrate in the reaction mixture.

The residual gas, which mainly consists of the diluent (usually nitrogen) of the oxygen-containing gas used to produce the nitrogen oxide-containing gas mixture from ammonia and possibly unconverted NO ₁ and unconverted oxygen and H ₂ O, monoamine and 13-DiaryKr. contains azenes in the vapor phase, is separated from the triazene-containing reaction liquid and expediently transferred through a pipeline into an exhaust gas removal system under such conditions that there is no deposition of aromatic diazonium nitrate on the pipe walls. An advantageous method for preventing the accumulation of diazonium nitrate in the pipeline is described in the separating application P 26 60 144.5.

The following examples illustrate the invention.

example 1

A gas mixture consisting of 4.5 mol% NO, 63 mol% NO ₂ , 683 mol% nitrogen and 193 mol% water vapor (NC concentration 11 ^ mol%; * -1.6) is prepared by applying an ammonia / air mixture with a content of 12.1 mol% ammonia, 18.1 mol% oxygen and 1.7 mol% water vapor (from the ambient air) at an overpressure of 8.16 atm directing a heated at 900 ⁰ C network catalyst comprising a platinum / rhodium alloy (10% Rh) and cool the resulting gas mixture at 200 ⁰ C and about under said pressure holding Under these conditions all of the oxygen in about 3 sec. consumes

132.4 g of aniline are introduced into a 150 ml glass reactor at room temperature, which is equipped with a stirrer, external cooling jacket, a heated side arm gas inlet capillary tube (opening near the reactor floor), a thermocouple and a 150 mm long , water-cooled condenser or condenser connected, 150 mm long upper outlet pipe is excluded

The aforementioned gas mixture is then introduced at an average tea door of 200 ° C. (175 to 225 ° C.) and a pressure of 1 atm through the heated GueinlaB tube with a throughput of 342 ml / mm, with aniline having room temperature the gas supply is du stirred at a speed of about 2000 rpm This stiffens Anflin 1

temperature of the aniline to 45 to 50 ⁰ C; it is kept in this area by air cooling. Exit the reactor through the outlet tube and condenser at a rate of 274 ml / min. Exhaust gases (0.5 to 0.7% by volume NO, no NO ₂ and no oxygen), which are released into the atmosphere.

After 180 min. Interrupting the gas stream, let d-! S cool reaction mixture at 3O ⁰ C, separating the organic layer from the aqueous layer. The organic layer (133.2 g) has the following composition after neutralization: 19.8% by weight 13-diphenyltriazene, 1.63% by weight p-aminoazobenzene, 0.121% by weight o-aminoazobenzene, 0.177% by weight % o-, m- and p-aminodiphenyl, 0.086% by weight HNO ₃ , 1.9% by weight H ₂ O and 73.1% by weight aniline. Taking into account the total attributable organic products, 21.7% of the aniline was converted into products after 180 min. On this basis, the yield of 13-diphenyltriazene is 91.1% (weight of the triazene divided by the weight of the total attributable , solids derived from aniline).

If o- or m-toluidine is used instead of aniline in the aforementioned process, one obtains under Appropriate results were obtained with 13-o- or 13-m-tolyltriazene.

Example 2

The process of Example 1 is repeated with the exception that the mass temperature of the aniline is kept at 25 ° C. by water cooling. The weight of the organic layer obtained in this case is 1393 g. Based on an aniline conversion of 203%, the following yields are achieved: 96.1% 13-diphenyltriazene, 33% p-aminoazobenzene and 0.26% o-aminoazobenzene. At 25 ° C, the exhaust gas contains 0.5 to 7% NO, nitrogen, aniline and water (no NO ₂ and no oxygen).

Example 3

The procedure of Example 1 is repeated with the exception that a 300 ml reactor and a gas mixture of 10 mol% NO ₂ and 90 mol% nitrogen are used. This gas mixture is obtained when the ammonia concentration is 10.7 mol% and the oxygen concentration is 18.1 mol% and the water vapor is then separated from the product gas. In this case, the gas mixture is introduced into the aniline (1994 g) at 25 ° C. with a flow rate of 375 ml / min. The mass temperature of the aniline increases to 35 ° C. After 204 minutes, the gas flow is interrupted. The weight of the organic layer obtained is 206.7 g. Based on a degree of aniline conversion of 16.4%, the following yields are achieved: 42.4% 13-Diphenvtoiazene, 31.6% p-Aminoazobenzene, 11) 3% p-NitroaiüTin and 9.9% o-Nitroaniline. The exhaust gases (nitrogen, 700 ppm NO ₂ , aniline, water vapor, no oxygen) are cooled to 10 ° C. in the liquefier to condense out the vaporous aniline and triazene and then drained off.

Example 4

The procedure of Example 1 is repeated with the exception that a gas mixture of 5.7 mol% NO, 5.7 mol% NO ₂ , 20.5 mol% water vapor and 68.1 mol% nitrogen is used. This mixture is obtained if the starting gas has an ammonia content of 12.6% and an oxygen content of 18% having. In this case, the gas mixture is at an average temperature of 200 ° C (175 to 225 ° C) with a throughput of 750 ml / min, into the aniline (120 g) initiated The mass temperature of the increases Aniline to 5O ⁰ C to. The gas supply is interrupted after 90 minutes. Based on a degree of aniline conversion of 313%, the following yields are achieved: 90.4% 13-diphenyltriazene, 73% p-aminoazobenzene, 0.49% o-aminoazobenzene, 03% p-nitroaniline and

to 0.15% o-nitroaniline.

Example 5

The procedure of Example 1 is repeated with the exception that a gas mixture of 7.4 mol% NO, 3.6 mol% NO ₂ and 89 mol% nitrogen used. This mixture is obtained if a starting gas with an ammonia content of 13.7% and an oxygen content of 173% is used in the ammonia oxidation and the steam is then Bend separated from the product gas in this Paiie, the gas mixture is introduced at an average temperature of 200 ⁰ C (175 to 225 ° C) with a throughput of 150 ml / min, in a mixture of 664 g of aniline and 34 g of nitrobenzene (internal standard) approach is kept at a temperature of 50 to 55 ⁰ C. The gas supply is interrupted after 121 minutes. The weight of the organic layer obtained is 68.1 g. Based on a degree of aniline conversion of 12.6%, a 13-diphenyltriazene conversion yield of 963% and a p-aminoazobenzene yield of 3.7% achieved

Example 6

693 g of aniline are in a 150 ml glass reactor entered with an outer Cooling jacket, two heated side arm gas inlet capillary tubes (opening near the reactor floor), a thermocouple and a 150 mm long, water-cooled condenser

A consisting of 5.4% NO _2, 23% NO, 17% of steam and 74.7% nitrogen gas mixture (175 to 225 ° C) and a pressure of 1 atm at an average temperature of 200 ⁰ C through one of the heated gas feed pipes with a throughput of 150 ml / min, into the one kept at room temperature Aniline introduced through the second heated gas inlet pipe with a throughput of 125 ml / min, a second gas mixture consisting of 3% oxygen and 97% nitrogen at a through average temperature of 200 ⁰ C and a pressure of 1 atm in the aniline EIA In this way one achieves a final composition of 23% NO _2, 1.6% NO, 9.1% of steam, 1.4% O ₂ and 85% nitrogen . A gas is simulated by this mixture, which through Ammonia oxidation generated by the method according to the invention and subsequent dilution with nitrogen up to a ΝΟχ concentration of 44% During the gas supply, the aniline is stirred at a speed of about 100 rpm. The batch warms up to 45 to 50 ⁰ C; this temperature range is maintained by air cooling.

After 211 minutes, the gas supply is interrupted. That The weight of the organic layer obtained is 68.2 g. Based on an aniliric conversion factor of The following yields are achieved 243%: 76.6% 13-diphenyltriazene. 193% p-aminoazobenzene, 1.6% o-aminoazobenzene, 14% p-nitroaniline and 1% o-nitroaniline.

Example 7 Example 8

The process according to the invention is carried out continuously as follows:

(a) Gas mixture containing nitrogen oxide

Nitric oxide and air are atm at an overpressure of 5.4 at a rate of 331 or 4.10 normal liters / min, fed into a tubular reactor case providing for a sufficient residence time that 95 are converted to 97 ¹ M) of the fed oxygen and a NO, arises, at which χ has the value 1.5. Heated nitrogen is added to the product gas with a throughput of 23 normal liters / min; of the final gas stream then contains 103 mole% NO, is (at a temperature of 74 ⁰ C) and less than 12:14 mole% residual oxygen. This gas mixture (with the exception of d: s water) simulates the mixture that would be produced by burning 123% ammonia in air with my relative humidity of 80% at JO "C.

(b) Reaction of aniline with the
nitrogen oxide-containing gas mixture

Aniline and water (the latter in the amount which would be present in the gas obtained by ammonia oxidation described under (a)) are delivered with throughputs of UO ml / min and 4.6 ml / min. The solution of 13-diphenyltriazene in aniline obtained as a reaction product and the gases formed in the tubular reactor also reach the separating device from which the Fluid is continuously withdrawn to maintain a constant level. A part of the withdrawn liquid is recovered, while another part ^{is returned to the tubular reactor through a cooler to maintain a temperature of 40 to 50 °} C. with a throughput of about 2300 ml / min.

The nitrogen-containing NCvStrom produced according to (a) is conducted simultaneously with the recycled aniline solution stream through the reactor The product * s (liquid and gas) is in the above-described manner into the separator, the gas is cooled in the condenser at 16 ⁰ C with the Condense vaporous aniline and 13-diphenyltriazene, and then drained. The analysis of the exhaust gas shows 134% NO and no NO ₂ (NOr consumption 90% X

Analysis of samples taken periodically over an operating period of 6 hours 7 minutes reveals the presence of 19% by weight of 13-diphenyltriazene, 1.2% by weight of p-aminoazobenzene and 0.05% by weight of aminodiphenylene. The proportion of nkht-converted aniline is 76%. On this basis, a 13-diphenyltriazene yield of 93% is achieved

Part of the nitrous gas stream from a plant serving for nitric acid synthesis for a technical ammonia oxidation process (AOP plant) is continuously withdrawn and converted with aniline within 155 minutes Regular analysis contains 11.4 to 11.6 mol% NH ₃ , catalytically at about 900 ⁰ C and an excess pressure of 8.5 atm over a platinum network catalyst to a nitrogen oxide, water vapor, a certain amount (3 Vol%) unreacted Oxygen and nitrous gas containing nitrogen as the remainder burned At a point in the AOP system where the gas was cooled to about 540 ° C., part of the gas is drawn off via a pipe with a throughput Mz of 63.6 kg / hour. The gas is transferred to a heat exchanger, where it is ^{cooled to 190 °} C. within about 1.5 seconds, and then fed into a tubular reactor where it is brought into contact with the recycled aniline solution at a throughput of 95 liters / minute will. The outlet of the tubular reactor opens into a gas / liquid separator, which is set up for continuous discharge.The solution of 13-diphenyltriazene in aniline and the gases generated in the reactor reach the separator, from which liquid is continuously withdrawn. Fresh aniline is continuously added to the liquid stream withdrawn from the separating device at a throughput of 216 kg / hour. The product solution is continuously withdrawn so that the material inventory in the reactor and in the separating device is kept constant. Part of the withdrawn liquid is recovered, while another part is returned to the reactor via a cooler (to remove the heat of reaction from the system and to maintain a temperature of 50 to 55 ° C in the reactor and in the separating device) .The temperature at the tubular reactor inlet is 47 to 50 ⁰ C; the overdrive is 2.4 atm at the reactor inlet and 03 atm at the outlet (in the gas / liquid separator). The tubular reactor has a volume of 5.2 liters . In the separating device (the total volume of which is around 45 liters), a liquid supply of around 11 liters is maintained.

The analysis values of samples of the product solution are shown in the table below. The yield of 13-diphenyltriazene, based on aniline, is 89% (degree of aniline conversion 17%).

13-diphenyl triazene p-aminoazobenzoI o-aminoazobenzene Aminodiphenyls

Weight * 163

0.16

007

Claims (9)

Patent claims: 1. Process for the preparation of 1,3-diaryltriazene by diazotization of primary aromatic Monoamines and coupling of the resulting diazonium salt with unreacted monoamine, characterized in that one successively (a) Ammonia is catalytically oxidized with the aid of a gas containing molecular oxygen at 800 to 950 "C to a gas mixture which contains a nitrogen _{oxide component NO x} in the form of nitrogen dioxide or a mixture of nitrogen dioxide and nitrogen oxide, where χ in the range of about 1.1 to 2.0 and is (1 + n) and π is the NOz fraction, and (b) the ^{gas mixture, cooled to below 500 °} C., is brought into contact with an optionally substituted primary aromatic monoamine in the liquid phase in such a way that a monoamine temperature in the range of about 25 to 90 ^° C. is established during the contact, and the reaction is interrupted if at least about 5% by volume of unused monoamine are still present. 2. The method according to claim 1, characterized in that one is practically oxygen-free Produces mixture of nitrogen dioxide and nitrogen oxide and brings it to reaction with the monoamine 3. The method according to claim 1 or 2, characterized in that the primary aromatic Monoamine uses an unsubstituted, alkyl-substituted or halogen-substituted aniline or naphthylamine 4. The method according to claim 1 to 3, characterized in that air is used as the molecular oxygen-containing gas and the content of nitrogen oxides in the gas mixture is about 10 to 12 mol% and χ in NO, in the range of about 1 β to 1, 7 lies 5. The method according to claim 1 to 4, characterized in that the gas mixture has a temperature in the range of about 25 to 350 ⁰ C immediately before its contact with the monoamine. 6. The method according to claim 1 to 5, characterized in that the monoamine during maintains its contact with the gas mixture at a temperature in the range of about 40 to 60 ° C 7. The method according to claim 1 to 6, characterized in that the gas mixture with pure monoamine 8. The method according to claim 1 to 7, characterized in that the reaction is interrupted when at least about 40 wt .-% unused monoamine are present. 9. The method according to claim 8, characterized in that the reaction is interrupted when at least about 60% by weight of unused monoamine are still present