CH638489A5 - Process for preparing and isolating haloacylamides - Google Patents

Description

The invention relates to chemical processes for the production and production of haloacylamides, in particular haloacetanilides, which are used in agriculture e.g. B. can be used as pesticides or plant growth regulators.

Haloacylamides and haloacetanilides of the type described here have hitherto been prepared using a number of known processes. In the process described in US Pat. No. 2,863,752 (Re 26,961), N-substituted 2-haloacetanilides are prepared by reacting a primary or secondary amine with the acid chloride of haloacetic acid, usually in the presence of caustic soda, in order to do this Neutralize hydrogen halide by-product. A similar process is set out in DE-OS 1 903 198; the intermediate and end products described therein are characterized by the N-substituent lower alkoxyethyl, to the ethyl radical of which one or two methyl groups can be attached.

6o In a further known process, which is described in US Pat. No. 3,574,746, N-substituted N-cycloalkenyl-2-halogenoacetamides are prepared by halogenoacetylation of the corresponding N-substituted cycloalkylimine in the presence of an acid acceptor.

65. In US Pat. Nos. 3,442,945 and 3,547,620, yet another process for the preparation of 2-haloacetanilides is described in which the suitable intermediate, namely an N-halomethyl-2-haloacetanilide, with the ge

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suitable alcohol, preferably in the presence of an acid binder. An analogous method is described in CA-PS 867 769; therein fluoroacylaminotri-chloromethylchloromethane is reacted with a thio compound of the formula Me-S-R, in which Me denotes H or alkali metal. If the thio compound is used in its free form, then it is appropriate to use an acid binder; however, if the thio compounds are used in the form of their salts, the addition of an acid binder is not necessary.

The methods of U.S. Patent 2,863,752, 3,442,945 and 3,547,620 cited above are also identified in U.S. Patent 3,875,228 as useful for the preparation of 2-haloacetamides, also described as acylamines, for which N -substituted (hydrogen, lower alkyl, alkoxy-methyl, allyloxymethyl or methoxyethyl) N-chloroacetyl-aminoindane serve as examples.

For the present invention, which relates to the alcoholysis of the N-substituted N-haloalkyl-2-haloacylamide or -2-haloacetanilide intermediate, the methods are applicable, which, for. B. in the above-mentioned US Pat. Nos. 3,442,945, 3,547,620 and 3,875,228 for the preparation of the 2-haloacetanilide intermediate by haloacetylation of the appropriate phenylazomethine. See also U.S. Patent 3,637,847.

In one in the Journal of the Chemical Society, Volume 1, pp. 2087-88 (1974) by O-.O. Orazi et al. Methods described are methylated N-substituted N-halo amides and imides using diazomethane on the nitrogen-halogen bond to produce the corresponding N-substituted N-halomethyl amide or imide, followed by condensation with nucleophiles. One embodiment of this process relates to the reaction of N-chloro-N-methyl-2-chloroacetamide with diazomethane to produce the corresponding N-chloromethyl-N-methyl-2-chloroacetamide, which can then be reacted with a nucleophile.

Nosubstituted N-chloromethyl- and N-bromomethylcycloalkenyl-2-halogenoacetamides are described in Examples 47 and 54 in the above US Pat. No. 3,574,746; these are representative of the type of compounds which can serve as intermediates in the process according to the invention. Other known processes for making some of the intermediates used in this invention include N-haloalkylation of a suitable aniline and subsequent N-haloacylation. For example, N-2-chloroethyl- or N-2-chloro-l-methylethyl-2-halogenoacet-anilides by reacting the corresponding aniline with 2-chloroethyl-p-toluenesulfonate or 2-chloro-l-methylethyl-p-toluenesulfonate and subsequent ones Chloroacetylation can be produced. In a further process for the preparation of the N-haloalkyl intermediate, the suitable haloalkanes, e.g. B. 1-Chloro-2-bromoethane, reacted with the appropriate aniline, followed by chloroacetylation.

In the process for the preparation of N-substituted 2-haloacetanilides by alcoholysis of the corresponding N-haloalkyl-2-haloacetanilide intermediate compound, hydrogen halide is produced as a by-product, which not only adversely affects the yield of the desired product but also the environment . Therefore, as mentioned in U.S. Patents 3,442,945,3,547,620 and 3,875,228 above, it is necessary to carry out the alcoholysis in the presence of an acid binder. Acid binders used in known processes include inorganic and organic bases, such as. B. alkali metal and alkaline earth metal hydroxides and carbonates, e.g. Sodium and potassium hydroxide, sodium carbonate, etc., tertiary amines, e.g. Trimethyl and triethylamines, pyridine and pyridine bases, ammonia, quaternary ammonium hydroxides and alcoholates; Metal alcoholates, e.g. Sodium and potassium methylates, ethylates, etc. Both the hydrogen halides and the acid binders can cause disadvantageous and undesirable side reactions, so they represent a disadvantage of the previously known processes.

A disadvantage frequently encountered in the known processes is that the acid binder reacts with the by-product hydrogen halide and forms insoluble precipitates, which have to be separated off and eliminated from the reaction mixture. The separation of the desired product from unnecessary by-products often requires the removal of solvents used, washing with water, steam stripping of hydrogen halide, dehydration, filtration and / or stabilization of the product. Other purification processes include fractional distillation under reduced or positive pressure, solvent distillation, film distillation, recrystallization, etc. described in Example 4 of the above-mentioned US Pat. Nos. 3,442,945 and 3,547,620 that in the preparation of N- (butoxymethyl) -2'-tert-butyl-6'-methyl-2-chloroacetanilide (trivial name " Terbuchlor ») of acid binders, ie Triethylamine, a voluminous precipitate of fine triethylamine hydrochloride needles, which must be removed by washing with water, solvent removal and filtering off. The same problem is described in PS 3 574 746 (see column 6, lines 18 to 33).

Is z. B. ammonia as an acid binder in the production of 2 ', 6'-diethyl-N- (methoxymethyl) -2-chloroacetanilide (trivial name "Alachlor" and active ingredient in the commercial herbicide "Lasso", registered trademark of the patent owner), then forms large quantities of ammonium chloride as a by-product and must be removed.

In some cases, during or after the alcoholysis of the N-haloalkyl intermediate, the large amount of the hydrogen halide by-product formed can be removed by conventional distillation. However, the hydrogen halide itself is a polluting gas. Furthermore, in some cases, distillation of the reactant alcohol and the by-product hydrogen halide leads to the generation of alkyl halide and water, and water is detrimental to the product yield. In addition, a certain proportion of the hydrogen halide remains in the reaction mixture and must be removed by an acid binder, which, as already mentioned, forms solid waste products. Previous work in the patentee's laboratories on the alachlor process attempted to remove the by-product HCl with excess methanol using conventional vacuum distillation. However, the N-chloro-methyl intermediate and the end product (alachlor) had to be used for a long time, i.e. about 2 hours, the adverse effects of HCl, water and other by-products, which led to a sharp reduction in alachlor yield. It was concluded from this that an acid binder should be used during or after the distillation stage, but the disadvantages already mentioned occurred.

In view of the energy saving and pollution that must be considered in the disposal of process wastes, it has become increasingly important to find new processes which have the adverse effect of all types of wastes, i.e. Solids, liquids and / or gases are excluded from chemical processes or reduced. In some cases, harmful by-products can be reprocessed and their components returned to the process. In other situations

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By-products can be cleaned or converted into other usable products. However, each of these methods requires additional capital investments, processing costs and energy consumption. Accordingly, it is preferable to avoid manufacturing environmentally harmful products as much as possible.

Another problem with the known processes for the preparation of 2-haloacetanilides is that they are batch processes with the associated disadvantages, especially in large-scale industrial production processes.

The aim of this invention is therefore an improved process for the preparation of 2-haloacylamides or 2-haloacetanilides, with which the disadvantages of the previous processes are overcome. Above all, it concerns a procedure

This has the advantage that no acid binder is required and practically no solid waste products are generated, which avoids costs for raw material, equipment and separation as well as environmentally harmful waste disposal.

The invention further relates to a process which is continuous, simple and inexpensive to carry out, saves energy, reduces pollution, but nevertheless achieves yields and purities which are just as high or higher than in the previous processes.

The method according to the invention is defined in claim 1.

A particularly interesting subgroup of compounds which can be prepared by the process according to the invention include haloacetanilides of the formula:

IV

wherein

R1 and R2, which are the same or different, denote hydrogen, halogen, C 6 alkyl, haloalkyl, alkoxy or alkoxyalkyl,

R3 denotes hydrogen, halogen, C [_6-alkyl, haloalkyl, alkoxy, alkoxyalkyl, alkylthio, CN, NO2 or CF3 or can be connected to R1 or R2 to form an alkylene chain having up to 4 carbon atoms,

R4 and R5, which are the same or different, denote hydrogen, fluorine, C 1-8 alkyl, haloalkyl, alkoxy or alkoxyalkyl and a is an integer from 0 to 3.

Preferred haloacetanilides are those in which R1, R2 and R6 are C1-6-alkyl, R4 and R5 are hydrogen or C1-6-alkyl, R7 mono-haloalkyl, Y and Y1 are oxygen, a is zero and b is 1 or 2.

In the most preferred embodiment, the process according to the invention for the production of alachlor is used by reacting 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetanilide and methanol, as described in Example 1.

In the preferred embodiments, the sequence of reaction and separation mentioned in claim 1 is repeated several times in order to ensure complete conversion of the compound of the formula II into the compound of the formula I. In the most preferred embodiment, the process is effectively carried out in two stages or reaction / separation sequences; doing so

A) reacting a compound of formula II with a compound of formula III in a first reaction zone;

B) an outflow of the reaction mixture from stage A is passed into a first separation zone, from which the majority of the by-product HX quickly emerges as a complex mixture with the compound of the formula III and a product stream which mainly comprises a compound of the formula I and an unreacted compound of the Formula II contains are removed;

C) the product stream from the first separation zone is passed into a second reaction zone, into which an additional amount of the compound of the formula III is also passed for reaction with the unreacted compound of the formula II;

D) an outflow of the reaction mixture from stage C is passed into a second separation stage, from which practically all of the remaining residual by-product HX is rapidly removed as a complex mixture with the compound of the formula III and a product stream which contains the compound of the formula I and traces of impurities will.

The special features of the method according to the invention include:

1. There is no need to add a base, which has been used in the previous processes as an acid binder for released hydrogen halide. 2. There are no recovery systems for the neutralization by-product from 1), i.e. the by-product 45 does not end up in the environment. 3. The by-product hydrogen halide is separated off as a complex mixture with the compound of the formula III in the product separation step or steps of the process preferably at the same time and usually within less than 0.5 minutes after equilibration of the reaction mixture.

In preferred embodiments of the invention, the molar ratio of the compound of the formula III to the compound of the formula II in stage A is higher than 1: 1; Usually it is in a range from about 2 to 100: 1 and, in the case of the alachlor process, in a range from about 2 to 10: 1, preferably 4 to 5: 1.

The reaction temperatures in stage A depend on the 60 reactants and / or solvents or diluents used. Generally, it is temperatures at which mixtures of alcohols of formula III and / or solvents or diluents with the by-product hydrogen halide complexes, e.g. azeotropic mixtures form without any significant decomposition of the reaction compound of the formula II or the desired product of the formula I due to a reaction with hydrogen halide. Generally a temperature

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between -25 and +125 'C or above, depending on the flow / boiling point of the reactants.

In the embodiments of the invention in which a multiplicity of reaction / separation sequences or stages are used, the hydrogen halide concentration in the successive reaction zones is in each case significantly reduced, which is why the respective reaction temperatures are generally somewhat above the temperatures used in stage A, to quickly drive the reaction of the unreacted compound of the formula II with additional alcohol to completion. The temperatures in the second and all subsequent reaction zones are accordingly generally between -25 and +175 C or above if necessary.

The suitable temperatures and pressures in the separation zone or zones are between 50 and 175 ° C or 1.0 to 300 mm Hg absolute pressure, depending on the boiling point of the particular compound of the formula III.

example 1

The use of the process according to the invention for the production of alachlor is described. This procedure is effectively carried out in a two-step reaction / separation sequence as follows.

Stage 1. Molten (45-55 ° C) 2 ', 6'-diethyl-N-chloromethyl-2-chloroacetanilide is passed into a continuous mixer at a rate of 46.67 kg / h and mixed with practically anhydrous methanol, which with 27.24 kg / h is passed into the mixer. The mixture is pumped through a tubular, thermostated reaction vessel that is maintained at 40 to 45 ° C and is long enough to allow a residence time of at least 30 minutes. The reaction gives a yield of about 92% 2 ', 6'-diethyl-N- (methoxymethyl) -2-chloroacetanilide (alachlor) and hydrogen chloride, based on the N-chloromethyl intermediate. The HCl generated is dissolved in excess methanol. The outflow from the reaction vessel is passed to a surface evaporator which is operated at 100 ° C. and 30 mm Hg absolute pressure. A complex mixture is removed and fed into a methanol recovery system.

Stage 2. The product stream from the evaporator in stage 1, which mainly contains alachlor and unreacted 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetanide, is passed into a second continuous mixer, in which further methanol is also added 27.24 kg / h is fed. The mixture is then passed into a second reaction zone which also contains a tubular reaction vessel equipped with a thermostat, which is kept at 60 to 65 ° C. and gives a residence time of 30 minutes. The outflow from this reaction vessel is passed into a second surface evaporator, which is operated at 100 ° C. and 30 mm Hg absolute pressure, from where a complex mixture of methanol and practically all of the remaining HCl is removed. The methanol / HCl mixture from this second stage evaporator is mixed with the methanol / HCl mixture from the first stage evaporator and introduced into a methanol recovery system, from which anhydrous methanol is recovered and returned to stage 1.

The product stream from the stage 2 evaporator contains alachlor in practically quantitative yield and over 95% purity, together with minor amounts of impurities. As made, this alachlor can be effectively used as a herbicide.

As can be seen from this example, the reaction / separation sequence of stage 1 gives alachlor in high yield. Under optimal conditions with regard to purity and concentration of the reactants, temperatures, residence time in the reaction vessel and the separation zones, etc., at least one reaction / separation sequence, which corresponds to the process in stage 1, would be sufficient to Ala-s chlorine or other compounds of Manufacturing Formula I in commercial quality.

Example 2

Preparation of 2-chloro-2 ', 6'-diethyl-N- (ethoxyme-io thyl) acetanilide.

About 5.5 g (0.02 mol) of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide were dissolved in 25 ml of ethanol and placed in a bath at 45 ° C. for 30 minutes. Excess ethanol was quickly removed on a vacuum rotary evaporator at 50 ° C i5 and 10 mm Hg. 25 ml of fresh ethanol were added to the remaining oil and the mixture was kept at 65 ° C. for 30 minutes. Excess ethanol was removed again using a rotary evaporator. About 5.80 g of pale amber oil was obtained; Gas-20 chromatography gave 92.8% of the desired product and 1.7% of 2-chloro-2 ', 6'-diethylacetanilide (by-product). Product yield: 94.5%.

Example 3

Using the procedures, operating conditions and amounts of reactants described in Example 2, but using isopropanol instead of ethanol, 5.92 g of product was obtained. Analysis of the pale amber oil showed 90.2% 2 ', 6'-diethyl-N- (isopropoxyme-30thyl) -2-chloroacetanilide (89.4% yield) and 1.8% of the secondary amide as a by-product 2' , 6'-diethyl-2-chloroacetanilide.

Example 4

35 Using the method described in Examples 2 and 3, but using 1-propanol as the reacting alcohol, 5.66 g of a lemon yellow oil were obtained, the analysis of which was 92.8% (87.9% yield) 2 ', 6 '-Diethyl-N- (n-propoxymethyl) -2-chloroacetanilide and 1.2% of the corresponding-40 secondary amide as a by-product.

Example 5

The same procedure was used as in Examples 2 to 4, but isobutanol was used as the reacting alcohol. 6.20 g of an oily product were obtained, the analysis of which was 96.4% (97% yield) 2 ', 6'-diethyl-N- (iso-butoxymethyl) -2-chloroacetanilide and 3% of the corresponding secondary amide as a by-product.

50 Example 6

The procedure of Examples 2 to 5 was repeated, but 2-chloroethanol was used as the reacting alcohol. 6.96 g of a slightly amber oil was obtained. His analysis showed 86.0% (94.0% yield) of 2 ', 6'-di-55-ethyI-N- (chloroethoxymethyl) -2-chloroacetanilide.

Example 7

The same procedure was used as in Examples 2 to 6 60, but n-butanol was used as the reacting alcohol. 6.18 g of a light lemon oil were obtained, the analysis of which 98.8% (99% yield) 2 ', 6'-di-ethyl-N- (n-butoxymethyl) -2-chloroacetanilide (this is buta-chloro) and gave 1% of the corresponding secondary amine as a 65 by-product.

For the above examples, the NMR analysis showed that the respective products showed the expected chemical structure.

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The following discussion and the additional test data of Examples 8 to 12 are intended to serve to further explain the advantages of the method according to the invention.

The reaction between compounds of formulas II and III is a reversible second order reaction. Equation 1 below, for which the reaction in Example 1 is exemplary, explains this reaction:

C-CH2C1

ch2ci

(a)

CH3OH

(b)

cch2ci

+ HC1

ch2och3

(c)

(d)

Since the reaction is reversible, an equilibrium is established; this balance is affected and depends on various factors such as the alcohol concentration and / or the concentration of the by-product hydrogen halide. For example, in equation 1) with increasing alcohol concentration (b) and thus increasing ratio of the reactants (b) :( a) (up to a given practical maximum) the equilibrium shifted to the right, since additional starting material (a) was converted and thus more product (c) and by-product hydrogen halide (d) is generated.

Another way to shift the equilibrium of equation 1) to the right is to remove the hydrogen halide (d), which can be done by adding an acid binder, e.g. tertiary amines such as triethyramine, can occur, as in the above-mentioned US Pat. Nos. 3,547,620, 3,442,945 and CA Pat. No. 867,769. However, the use of acid-binding substances leads to other disadvantages already described.

In the mentioned CA-PS 867 769 it is proposed

that the acid binder is unnecessary when the starting thio compound is an alkali metal salt; the obvious reason for this is that the salts themselves form the basic medium, which is favorable for the special reaction described in this PS. On the other hand, if the thio starting compound is used in its free form, then an acid binder must be used to set the by-product hydrogen chloride.

U.S. Patent Nos. 3,547,620 and 3,442,945 say

that the described process is preferably carried out in the presence of an acid binder (and this is also exemplified in all embodiments), but it can be deduced that the same process can also be carried out without the addition of an acid binder. However, as mentioned above, attempts to perform the process described in U.S. Patent Nos. 3,442,945 and 3,547,620 to produce the preferred product, alachlor, without adding an acid binder to remove the hydrogen halide by-product, resulted in greatly reduced alachlor yields.

In order to obtain further comparable results when carrying out the process described in the above PS 3 442 945 and 3 547 620 without an acid binder in comparison with the process according to the invention,

the procedures described in Examples 8 to 12 were carried out. For each of these examples, the starting material N-chloromethyl-2-chloroacetanilide was converted by reacting the corresponding substituted N-methylene ani-

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Lins made with haloacetyl halide as described in U.S. Patents 3,442,945 and 3,547,620.

Example 8 (comparison)

Preparation of 2-chloro-2 ', 6'-diethyI-N- (methoxymethyl) acetanilide (alachlor) according to Example 5 of US Pat. Nos. 3,447,620 and 3,442,945.

100 g of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide, analytical value 96.0% (0.350 mol), dissolved in about 70 g of benzene, became 65.8 g (2.054 mol) of methanol given; an exothermic reaction took place. The reaction mixture was refluxed at 63 ° C and excess (about 63.3 g) triethylamine was added dropwise over 1.5 hours. During this addition, the temperature rose to about 70 ° C, where it was held for about 10 minutes after the addition of triethylamine was complete. After cooling to 30 ° C, the reaction mixture was washed with two 170 ml portions of water. The product obtained in a heavy, oily layer was cleaned of solvent and dehydrated by vacuum distillation to a final temperature of about 70 ° C at 1 mm Hg. The remaining amber oil weighed 96.15 g, gas chromatography gave 90.4% product and 4.9% 2-chloro-2 ', 6'-diethyl-acetanilide (by-product). Unreacted starting material was not present in the product. Product yield: 92.0%.

Example 9 (comparison)

Preparation of alachlor according to Example 5 of US Pat. Nos. 3,547,620 and 3,442,945, but without using an acid binder.

100 g of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide, analysis value 96.0% (0.350 mol), dissolved in about 70 g of benzene, were added to 66 g (2.059 mol) of methanol. An exothermic reaction resulted and the reaction mixture was heated under reflux (at 63 ° C.) for a further hour. Acid binder was not added. After the reflux ended, excess methanol and solvent were removed by vacuum distillation to a final temperature of 70 ° C at 1 mm Hg. About 96.83 g of a light lemon yellow oil was obtained which, according to gas chromatography, contained 83.7% of product, 7.5% of by-product 2-chloro-2 ', 6'-diethylacetanilide and 5.5% of unreacted starting material. The product yield was 85.8%.

The lack of an acid binder in this example resulted in a 6.2% reduction in yield. In this procedure the reaction was not complete

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shifted to the right. The HCl by-product consequently reduced the conversion, and the unreacted starting material was found as an impurity in the product.

Example 10 (comparison)

Preparation of alachlor according to Example 5 of U.S. Patents 3,547,620 and 3,442,945, but without the use of an acid binder and under optimized temperature conditions.

100 g of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide, analysis value 96.0% (0.350 mol), dissolved in about 70 g of benzene, were added to 66 g (2.059 mol) of methanol. An exothermic reaction occurred which caused the temperature of the reaction mixture to rise to 45 ° C where it was held for 1 hour. An acid binder was not added. Excess methanol and solvent were removed under vacuum distillation to a final temperature of about 80 C at 1 mm. About 96.20 g of oil were obtained, gas chromatography gave 85.8% of product, 6.2% of by-product 2-chloro-2 ', 6'-diethylacetanilide and about 4.6%

unreacted raw material. The product yield was 87.4%.

By optimizing the reaction conditions in the absence of an acid binder, the product quality (2.7%) and the yield (1.6%) were improved, but the basic problem, namely the incomplete reaction, had not yet been solved.

Example 11

Production of alachlor with the method according to the invention according to the embodiment in which a one-stage reaction vessel is used; the starting materials used were the same as in Examples 8 to 10.

10 g of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide, analytical value 96.0% (0.035 mol), were added to about 6.0 g (0.1873 mol) of methanol. An exothermic reaction occurred which raised the temperature of the reaction mixture to about 45 ° C where it was held for about 30 minutes. Excess methanol was quickly removed on a rotary vacuum evaporator to a final temperature of 70 C at 1 mm Hg. 9.80 g of slightly lemon-yellow oil were obtained, gas chromatography gave 91.0% of product, 1.7% of by-product 2-chloro-2 ', 6'-diethyl

acetanilide and 2.4% unreacted starting material. Product yield: 94.4%.

Despite the use of only one step, the quality and yield of the desired product were significantly improved over the previous processes, although the reaction was not complete (2.4% starting material in the product). A comparison with Examples 8,9 and 10 shows an obvious improvement, although no acid binder was used.

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Example 12

Production of alachlor in the absence of an acid binder according to the preferred method according to the invention using a multi-stage reaction vessel. is 10 g of 2-chloro-2 ', 6'-diethyl-N- (chloromethyl) acetanilide, analysis value 96.0% (0.0350 mol) were dissolved in 6.0 g (0.1873 mol) of methanol. An exothermic reaction took place, causing the temperature to rise to 45 ° C, where it was held for half an hour. Excess Me-20 ethanol was quickly removed on a rotary vacuum evaporator to a final temperature of 45 ° C at 1 mm Hg. A second amount of 6.0 g (0.1873 mol) of fresh methanol was added, the reaction mixture was heated to 65 ° C. and held at this temperature for half an hour. Excess methanol was removed as before. About 9.80 g of light lemon oil was obtained, the analysis of which showed 95.8% product, 1.4% 2-chloro-2 ', 6'-diethylacetanide and no unreacted starting material. Product yield: 99.4%.

30 A summary of the comparable results of the processes described in Examples 8 to 12 can be found in the following table. The "starting material" listed there is unreacted 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetanilide, and "by-product" means 35 2', 6'-diethyl-2-chloroacetanilide, the main acetani lid by-product in the procedures of all of these examples. Of course, smaller amounts of AcetaniÜd and other by-products are produced in addition to the large amounts of hydrogen halide and, as in the case of Example 8, the neutralization by-product triethylamine hydrochloride. The percentage of the yield relates to the starting material 2 ', 6'-diethyI-N- (chloromethyl) -2-chloroacetanilide.

table

Example No.

Type of procedure

Product analysis values%

Alachlor Alachlor Auxiliary Home

Yield (%) of product material

9

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11

12

Example 5 U.S. Patents 92,0 3,442,945 and 3,547,620 with base like 8 but without base 85.8

as in Example 9 87.4

under optimized

conditions

94.4 process according to the invention 1 stage

99.4 according to the invention

Procedure several stages

90.5

83.7

85.8

91.0 95.8

4.9

7.5 6.2

1.7

1.4

5.5

4.6

2.4

An analysis of the data in the above table shows the salient properties and decisive advantages of the method according to the invention, i. H. of Examples 11 and 12, in comparison with the previous method shown in Examples 8 to 10, 1. substantial increase in the alachlor yield, 2. improvement in the alachlor purity,

з. noticeably reduced by-product yield, 4. increased conversion of the starting material when working without base addition, 5. lack of a solid neutralization product, which is obtained in large quantities in the base addition process of example 8, which has hitherto been the technologically best process for the production of alachlor . These technical advantages must be added to the economic and ecological advantages already mentioned.

No solvent is required when carrying out the process according to the invention; however, in some cases, a solvent or diluent can be used to control the reaction and / or to facilitate the dissolution, dispersion, and / or recovery of reactants, by-products, and products. Suitable solvents or diluents are

и.a. those which are inert under the required reaction conditions, e.g. Petroleum ether, aliphatic and aromatic hydrocarbons e.g. Hexane, benzene, toluene, xylene, etc., and halogenated hydrocarbons, e.g. B. mono-chlorobenzene.

An advantage of the process according to the invention is that the reactant of the formula III can easily be separated from the complex mixture with the by-product hydrogen halide, purified and returned to one or more reaction stages of the process. In the same way, the hydrogen halide itself can also be easily obtained for use in many industrial processes, e.g. B. for etching metals, for Oxichlorierun-gene, electrolysis to elemental chlorine and hydrogen, etc., or it can be otherwise eliminated without harming the environment.

In a suitable raw material recovery and recycling system, which is shown here by way of example for the complex methanol / HCl mixture which is obtained in the alachlor process described in Examples 1, 11 and 12, the complex methanol / HCl mixture is made from the separation stage or stages fed into a distillation system from which purified methanol is obtained.

For the method according to the invention, the fact that the use of reactants, i.e. technical quality of compounds of formulas II and III is possible, but that the higher the purity of the reactants, the higher the quality of the compounds of formula I produced. In some cases, compounds of formula III, e.g. B. methanol, which contain smaller amounts of water, but it is much more advantageous to use anhydrous compounds, since water can cause hydrolysis of the reactants of the formula II and thus lead to a poorer product of the formula I. However, in the specific case where R6 is hydrogen, water itself can be used as the compound of Formula III to produce some compounds of Formula I by hydrolysis of the N-haloalkyl intermediate. For example, already described earlier that 2'-tert-butyl-6'-ethyl-N- (chloromethyl) -2-chloroacetanilide is hydrolyzed with water in the presence of an acid binder to give the corresponding N-hydroxymethyl compound, which is used as a herbicide ( see e.g. example 1 of GB-PS 1 088 397). It follows from this that in some embodiments of the method according to the invention a certain amount of water is disadvantageous for the

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Product yield may be, but not in other embodiments; this depends on the reactivity of the other reactants and the end products with water. Since hydrogen halides have an adverse effect on product quality, reaction participants which are practically free of hydrogen halides, such as e.g. B. HCl.

The representative compounds produced by the process according to the invention include those in which the groups of the formulas above have the following meanings:

R: hydrogen, CM8 alkyls, e.g. Methyl, ethyl, propylene, butyle, pentyle, hexyle, heptyle, octyle, nonyle, decyle, undecyle, dodecyle, pentadecyle, octadecyle, etc .; Alkeny-le, e.g. B. vinyl, allyl, crotyl, methallyl, butenyls, pentyls, hexenyls, heptenyls, octenyls, nonenyls, decenyls etc., alkynyls, e.g. B. ethynyl, propynyls, butynyls, pentynyls, hexynyls, etc .; the alkoxy, polyalkoxy, alkoxyalkyl and polyalkoxyalkyl analogs of the previous alkyl groups; Cycloalkyls and cycloalkylalkyls with up to 7 cyclic carbons, e.g. E.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, etc .; Cycloalkenyls and cycloalkadienyls with up to 7 cyclic carbons, e.g. Cyclopentenes, cyclohexenes and cycloheptenes which are mono- and di-unsaturated; Cwg aryl and aralkyl and alkaryl groups, e.g. Phenyl, tolyls, xylyls, benzyl, naphthyl etc. and also these R groups substituted with radicals which do not react with hydrogen, e.g. B. alkyl, alkoxy, halogen, nitro or cyano; if the substituent is a halogen atom, then it must not sit on the a-carbon, since it reacts with hydrogen in this position.

R \ R2, R4 and R5: hydrogen, fluorine, the C, _6-alkyls of R, haloalkyls, e.g. B. chloromethyl, chloroethyl, bromomethyl, bromoethyl, iodomethyl, trifluoromethyl, chloropropyl, bromopropyl, iodopropyl, chlorobutyl, iodobutyl and di- and trihalogen analogues thereof; Alkoxy, e.g. Methoxy, ethoxy, propoxy, butoxy, pentoxy and hexoxy and corresponding polyalkoxy and alkoxyalkyls, e.g. B. methoxy-methoxy, methoxyethoxy, ethoxymethoxy- ethoxyethoxy, methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, propoxymethyl, isopropoxymethyl, butoxymethyl, isobutoxymethyl, tert-butoxymethyl, pentoxymethyl, hexoxymethyl, etc.

R1 and R2 can also mean chlorine, bromine or iodine. R3 can be hydrogen, the halogen, alkyl, haloalkyl, alkoxy and alkoxyalkyl groups of R1, R2, R4 and R5, methylthio, ethylthio, propylthio, CN, NOz or CF3 or R3 can be R1 or R2 to form an Al -Cylene chain can be combined with up to 4 carbon atoms and so form the acylated 5-aminotetralins and acylated 4-aminoindanes, which are shown in the above-mentioned US Pat. No. 3,875,228.

R6 can be hydrogen, the CM0-alkyl, alkenyl, alkynyl and alkoxyalkyl groups of R; further oxo-alkyl groups corresponding to the above alkyl groups, e.g. B. 2-oxobutyl, 3-oxopentyl, 4-oxohexyl etc., further it may mean the C, _7-cycloalkyl, cycloalkenyl and alkyl-cycloalkyl groups of R; the C ^ aryl and aralkyl groups of R; Amino and mono- and disubstituted amino containing the above C, _6-alkyl, alkenyl or alkynyl groups and the above R6 groups substituted with alkyl, halogen, hydroxy, alkoxy, nitro, cyano or alkyl-thio can be.

R7 is C 1 -shaloalkyl, preferably C 2 -monohalogenalkyl, such as chloromethyl, chloroethyl, bromomethyl. Bromoethyl, iodomethyl, iodoethyl, fluoromethyl and fluoroethyl; Dihaloalkyls, such as 1,1-dichloromethyl, 1,1-di-

9

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

638 489

10th

brc-mmethyl, 1,1-diiodomethyl, etc. may also be present

X represents halogen, especially chlorine or bromine. The process according to the invention is particularly suitable for the preparation of the N-substituted-2-5 haloacetanilides defined above, in which R1, R2 and R6 are C 1-6 alkyl, R7

Monohalomethyl. Y and Y1 are oxygen, a is zero and b is 1 or 2, preferably 1.

The compounds of the formula I prepared by the process according to the invention are known compounds. Representative compounds of formula I have been described previously and are partially cited above.

s

Claims (23)

638489 2. The method according to claim 1, characterized in that the sequence of reaction and separation steps is repeated several times to ensure complete conversion of the compound of formula II into the compound of formula I. 2nd PATENT CLAIMS 1. Process for the preparation and production of compounds of the formula: Y I! R-N \ X-R t tc R5 -Y ^ -R6 in which R is hydrogen, optionally substituted by alkyl, alkoxy, halogen, hydroxy, nitro or cyano-substituted CM8-alkyl, alkenyl, alkynyl, alkoxy, polyalkoxy, alkoxyalkyl, polyalkoxyalkyl, C ^ -cycloalkyl, cycloalkylalkyl, cycloalkenyl, Cf> ls-aryl, Aralkyl or alkaryl means R4 and R5, which are the same or different, are hydrogen, fluorine, C, _6-alkyl, haloalkyl, alkoxy or alkoxyalkyl, R6 is hydrogen or optionally by alkyl, alkylthio, alkoxy, halogen, hydroxy, nitro or cyano substituted C, m-alkyI, alkenyl, alkynyl, alkoxyalkyl, oxoalkyl, C3_7-cycloalkyl, lower alkylcycloalkyl or -cycloalkenyl, C ^ | 2-aryl or aralkyl, -N (R8) 2, wherein R8 represents hydrogen, C, f , -Alkyl, alkenyl or alkynyl, R7 is C [_5-mono- or -dihaloalkyl, Y and Y1 are oxygen or sulfur and b is an integer from 1 to 4, characterized in that at least one sequence of reaction and Separation steps is carried out in the A) a compound of the formula: Y left, .C-R R-N \ R II I. Ix • i5 \ where X is halogen, with a compound of the formula: R6Y'H III is implemented, without the addition of acid-binding agents, and B) an outflow of the reaction mixture from step A is passed into a separation zone, from which a complex mixture of the by-product HX and the compound of the formula III and a product stream which mainly contains the compound of the formula I are rapidly removed. 3rd 638 489 wherein R1 and R2 independently of one another are hydrogen, halogen, C, _6-alkyl, haloalkyl, alkoxy or alkoxyalkyl; R3 is hydrogen, halogen, C, _6-alkyl, haloalkyl, alkoxy, alkoxyalkyl, alkylthio, CN, NOz or CF3 or can be linked to R1 or R2 to form an alkylene chain with up to 4 carbon atoms; R4 and R5 independently of one another are hydrogen, fluorine, Ci-6-alkyl, haloalkyl, alkoxy or alkoxyalkyl; R6, R7, Y, Y1 and b have the meaning given in claim 1, and a is an integer from 0 to 3. 3. The method according to claim 2, in which the reaction / s separation process is carried out in a sequence of two steps, characterized in that A) reacting a compound of formula II with a compound of formula III in a first reaction zone; io B) an outflow of the reaction mixture from step A is passed into a first separation zone, from which the majority of the by-product HX quickly emerges as a complex mixture with the compound of the formula III and a product stream which is mainly a compound of the formula I and one is not Contains -15 reacted compound of formula II are removed; C) the product stream from the first separation zone is passed into a second reaction zone, in which also an additional amount of the compound of formula III for the reaction 4. The method according to claim 3, characterized in that step A at a temperature between -25 and 30 +125 ° C is carried out. Ensure 5 ethyl-N- (methoxymethyl) -2-chloroacetanilide. 5. The method according to claim 3, characterized in that step C at temperatures between -25 and +175 ° C is carried out. 6. The method according to claim 3, characterized in that steps B and D are carried out at temperatures and pressures sufficient to separate a complex mixture of compound of formula III and hydrogen halide from the effluent from steps A and C. 7. The method according to claim 3, characterized in that the compound of formula III is used in an amount which corresponds to a molar ratio of> 1: 1 to the compound of formula II. 8. The method according to claim 7, characterized in that the molar ratio is in the range from 2 to 100: 1. 45 9. The method according to claim 3, characterized in that the complex mixture of HX and compound of formula III from step D is introduced into a recovery system in which the compound of formula III is removed from the hydrogen halide, purified and in the steps A so and / or C is returned. 10. The method according to claim 3, characterized in that the temperature in steps B and D between 50 and 175 ° C and the pressures between 1.0 and 300 mm Hg absolute pressure. ss 11. The method according to claim 1, characterized in that the compounds of the formula I are haloacetanilides of the formula IV, Y II IV 12. The method according to claim 11, characterized in that in the haloacetanilides R1, R2 and R6 C ^ alkyl, R4 and R5 are hydrogen or Cj ^ alkyl, R7 C1_2-mono-haloalkyl, Y and Y1 oxygen, a is zero and b is 1 or 2. 13. The method according to claim 12, characterized in that in the haloacetanilides R1 and R2 ethyl, R4 and R5 are hydrogen, R6 C, _6-alkyl, R7 is 2-chloromethyl and b is 1. 14. The method according to claim 13, characterized in that R6 is methyl. 15. The method according to claim 13, characterized in that R6 is ethyl. 16. The method according to claim 13, characterized in that R6 is a propyl isomer. 17. The method according to claim 13, characterized in that R6 is a butyl isomer. 18. The method according to claim 17, characterized in that the butyl isomer is n-butyl. 19. The method according to claim 1 for the production and production of 2 ', 6'-diethyl-N- (methoxymethyl) -2-chloroacetanilide, characterized in that at least one sequence of reaction and separation steps is carried out in which A) Methanol reacted with 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetanilide in a molar ratio of 2 to 100: 1 at temperatures between 25 and 65 ° C for 15 to 30 minutes without adding an acid binder will, and B) an outflow of the reaction mixture from step A is passed into a separation zone, from which a complex mixture of HCl and methanol and a product stream which mainly contains 2 ', 6'-diethyl-N- (methoxymethyl) -2-chloroacetanilide are rapidly obtained , be removed. 20. The method according to claim 19, characterized in that the reaction / separation sequence is repeated several times in order to convert the virtually complete 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetanilide to 2', 6 ' -Di- 20 is introduced with the unreacted compound of formula II; D) an outflow of the reaction mixture from step C is passed into a second separation zone, from which practically all of the remaining by-product HX quickly becomes complex 25 mixture with the compound of formula III and a product stream which contains the compound of formula I and traces of impurities are removed. 21. The method according to claim 20, characterized in that A) in a first reaction zone kept at 25 to 65 ° C. methanol with 2 ', 6'-diethyl-N- (chloromethyl) -2-chloro loacetanilide is reacted in a molar ratio of 2 to 10: 1 for 15 to 30 minutes without the addition of an acid binder; B) an outflow of the reaction mixture from step A is passed into a short path distillation zone, the temperatures at Ternis between 50 to 100 ° C and pressures between 30 and 300 mm Hg absolute pressure and from which a complex mixture of methanol and most of the by-product HCl as well as a product stream consisting mainly of 2 ', 6'-diethyl-N- (methoxymethyl) -2-chloroacetanilide 20 and unreacted 2', Contains 6'-diethyI-N- (chloromethyl) -2-chloro-acetanih'd, be removed; C) the product stream from the first separation zone is passed into a second reaction zone kept at 25 to 65 ° C., in which an additional amount of methanol is 25 reaction with the unreacted 2 ', 6'-diethyl-N- (chloromethyl) -2-chloroacetani! Id is introduced in an amount which corresponds to the amount which is in the first reaction zone over a period of 15 until 30 minutes was used; 30 D) an outflow of the reaction mixture from step C is passed into a second short path distillation zone, which is kept at temperatures between 50 and 100 ° C and pressures between 30 and 300 mm Hg absolute pressure, and from which a complex mixture of methanol and practically 35 the whole remaining by-product HCl and a product stream which mainly contains 2 ', 6'-diethyI-N- (methoxy-methyl) -2-chloroacetanilide and traces of impurities are removed. 22. The method according to claim 21, characterized in that the complex mixtures of methanol and HCl from steps B and D are combined and fed into a methanol recovery system, removed from the HCl and the methanol obtained is purified and into the steps A and / or B is returned. 45 23. The method according to claim 22, characterized in that the residence time of the reaction mixture in the short path distillation zones of steps B and D is shorter than 0.5 minutes.