GB2073173A

GB2073173A - Producing N-alkoxyalkyl-N- chloroacetyl-2,6-dialkylanilines

Info

Publication number: GB2073173A
Application number: GB8011232A
Authority: GB
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1980-04-03
Filing date: 1980-04-03
Publication date: 1981-10-14

Abstract

A process for producing N- alkoxyalkyl-N-chloroacetyl-2,6- dialkylanilines of the formula <IMAGE> in in which R1 and R2 independently represent methyl or ethyl, A is 1,2- ethylene group which can be substituted by 1 or 2 methyl groups, and R3 is a C1-3 alkyl, is disclosed, which comprises reacting a N- alkoxyalkyl-2,6-dialkylaniline of the formula <IMAGE> with chloroacetyl chloride in excess chloroacetyl chloride as solvent. The N-alkoxyalkyl-N- chloroacetyl-2,6-dialkylanilines of the above formula can be used for protecting plants from being infected by phytopathogenic microorganisms.

Description

SPECIFICATION Process for Producing N-Alkoxyalkyl-N Chloroacetyl-2,6-Dialkylanilines The present invention relates to an improved process for producing N-alkoxyalkyl-Nchloroacetyl-2,6-dialkylanilines of the formula I

in which R, and R2 independently of one another are each methyl or ethyl, A is 1 ,2-ethylene group which can be substituted by 1 or 2 methyl groups, and R3 is an alkyl group having 1 to 3 carbon atoms, by reacting an N-alkoxyalkyl-2,6dialkylaniline of the formula II

in which R,, R2, A and R3 are as defined under the formula I, with chloroacetyl chloride.

The N-a Ikoxyalkyl-N-chloroacetyl-2,6- dialkylanilines of the formula I have a pronounced action against phyto-pathogenic microorganisms, and are therefore used for protecting cultivated plants from being infected by phytopathogenic microorganisms. N-Alkoxyalkyl-N-chloroacetyl2,6-dialkylanilines of the formula I and their application are described for example in the U.S.

Patent Specifications Nos. 3,952,056 and 3,937,730.

The method of producing N-alkoxyalkyl-Nchloroacetyl-2,6-dialkylanilines of the formula I by reacting the corresponding N-alkoxyalkyl-2,6dialkylanilines of the formula II with chloroacetyl chloride is known. The reaction can be performed both in the absence and in the presence of inorganic or organic bases, such as sodium hydroxide, sodium carbonate, N,N-dimethylaniline and triethylamine. In carrying out the chloroacetylation in the presence of aqueous inorganic bases, there is however required a large excess of chloroacetyl chloride since a considerable part of the chloroacetyl chloride is lost as a result of hydrolysis. This is on the one hand uneconomical and on the other hand undesirable on account of the ecological problems created, because the acid formed as a result of hydrolysis has to be removed from the waste liquor.This disadvantage of the use of a large excess of chloroacetyl chloride can indeed be avoided by using organic bases, but in this case the respective amine hydrochloride formed has to be separated and the corresponding amine regenerated, a factor giving rise to additional expenditure.

Compared with the aforementioned processes, the process comprising the direct reaction of an N-alkoxyalkyl-2,6-dialkylaniline of the formula II with chloroacetyl chloride in an inert solvent in the absence of a base has the advantage that the hydrogen chloride formed during the reaction can be immediately separated in gaseous form. Since however the chloroacetyl chloride is used, for economical reasons, essentially in an equimolar amount, long reaction times are necessary for the complete carrying out of the reaction and for the complete separation of the hydrogen chloride. It is as a rule necessary to heat the reaction mixture for several hours at a temperature of 90 to 1 00C, in consequence of which secondary reactions, such as the splitting-off of ether and the formation of resinous by-products, are promoted.The yield of active substance is reduced as a result of these secondary reactions.

The processes mentioned in the foregoing are uneconomical by virtue of the disadvantages associated with them. It is therefore the object of the present invention to provide a process by which the N-alkoxyalkyl-N-chloro-acetyl-2,6dialkylanilines of the formula I can be produced, in a simple and economical manner, in good yields on a commercial scale.

It has been found that N-alkoxyalkyl-Nchloroacetyl-2,6-dialkylanilines of the formula I can be produced in excellent yields and with an excellent degree of purity by performing the reaction of N-alkoxyalkyl-2,6-dialkylanilines of the formula II with chloroacetyl chloride in excess chloroacetyl chloride as solvent. The process according to the invention therefore comprises reacting the N-alkoxyalkyl-2,6dialkylaniline of the formula II with chloroacetyl chloride in the presence of excess chloroacetyl chloride as solvent, distilling off the excess chloroacetyl chloride, washing the formed N-alkoxyalkyl-Nchloroacetyl-2,6-dialkylaniline of the formula I with water until neutral, and subsequently drying the product obtained.

The chloroacetyl chloride is used according to the invention in an amount of 2 to 20 mols, preferably 4 to 8 mols, per mol of N-alkoxyalkyl2,6-dialkylaniline of the formula II. The reaction is advantageously performed in the temperature range of 700C to the reflux temperature of the reaction mixture, preferably at the reflux temperature of the reaction mixture.

The washing of the product obtained after the excess chloroacetyl chloride has been distilled off can be carried out with water at 50 to 1 00C. It is advantageous to repeat the washing operation several times. It is also advantageous to add to the washing water an amount of alkali, particularly sodium hydroxide or potassium hydroxide, sufficient to bring the pH value of the water to 8 to 12. The product is subsequently dried, optionally after further washing with pure water, by heating at 100 to 1 200C in vacuo.

The process according to the invention can be performed either batchwise or continuously.

The process is performed batchwise advantageously by introducing the N-alkoxyalkyl2,6-dialkylaniline of the formula ll into boiling chloroacetyl chloride, and distilling off the excess chloroacetyl chloride in vacuo after completion of the reaction.

In carrying out the process continuously, it is advantageous to introduce simultaneously the chloroacetyl chloride and the N-alkoxyalkyl-2,6dialkylaniline of the formula II, at the reaction temperature, into the reaction vessel, and directly afterwards to concentrate the mixture in vacuo.

The continuous method of carrying out the process can be advantageously performed in a cascade reactor having 2 to 4 stages, or in a falling film reactor.

The hydrogen chloride formed during the reaction is separated in gaseous form, and can be compressed and fed into steel cylinders, or dissolved in water to form concentrated hydrochloric acid, or processed by oxidation into chlorine.

It is a particular advantage of the process according to the invention that the contamination of the environment with harmful substances is reduced to a minimum. A further advantage of the process according to thte invention is that the reaction of the N-alkoxy-2,6-dialkylaniline of the formula II with chloroacetyl chloride proceeds very rapidly because of the large excess of chloroacetyl chloride. Consequently, the time that the starting products and final products are held under the reaction conditions can be kept very short, with the result that secondary reactions, such as the splitting-off of ether and the formation of resinous by-products, are greatly reduced. In consequence of this reduction of secondary reactions and of the possibility of using the excess chloroacetyl chloride again in the reaction, losses of substances are avoided.A further advantage of the process according to the invention is finally that the quantity ratio of the reactants can be varied within very wide limits without the quality of the final product being disadvantageously affected.

It is therefore possible by the process according to the invention to produce the Nalkoxy-N-chloroacetyl-2,6-dialkylanilines of the formula I in a simple manner and in excellent yield and degree of purity.

The process according to the invention is further illustrated by the Example which follows.

Example 1356 g (12 mols) of chloroacetyl chloride is placed into a 3-litre three-necked flask provided with stirrer, dropping funnel and condenser, and heated to boiling. There is then added dropwise 207 g (1 mol) of N-(2'-methoxy-1 '-methylethyl)2-ethyl-6-methylaniline at such a rate that the solution always remains uniformly boiling and evolves gas. After the addition of N-(2'-methoxy1 '-methylethyl)-2-ethyl-6-m ethylaniline, the excess of chloroacetyl chloride is distilled off in a rotary evaporator at a pressure of 1 5 Torr. The crude product thus obtained is washed in a separating funnel with 200 ml of water, with the pH value of the washing water being adjusted to 8 by the addition of 30% sodium hydroxide solution. After separation of the aqueous phase, the product is firstly washed twice again with water, and then dried for 30 minutes at 11 OOC and 15 Torr. The yield is 273.8 g (96.6% of theory) of N-(2'-methoxy- 1 '-methyl-ethyl)-Nchloroacetyl-2-ethyl-6-methylaniline.

Claims

1. A process for producing N-alkoxy-Nchloroacetyl-2,6-dialkylaniline of the formula I

in which R1 and R2 independently of one another are each methyl or ethyl, A is a 1 2-ethylene group which can be substituted by 1 or 2 methyl groups, and R3 is an alkyl group having 1 to 3 carbon atoms, by reacting an N-alkoxyalkyl-2,6dialkylaniline of the formula Il

in which Ra, R2, A and R3 are as defined under the formula I, with chloroacetyl chloride, which process comprises reacting the N-alkoxyalkyl-2,6dialkylaniline of the formula II with chloroacetyl chloride in the presence of excess chloroacetyl chloride as solvent, distilling off the excess chloroacetyl chloride, washing the formed N a lkoxya lkyI-N-chloroacetyl-2,6-dia Ikylaniline of the formula I with water until neutral, and subsequently drying the product obtained.

2. A process according to Claim 1, wherein 2 to 20 mols of chloroacetyl chloride are used per mol of N-alkoxyalkyl-2,6-d.alkylaniline of the formula II.

3. A process according to Claim 1, wherein 4 to 8 mols of chloroacetyl chloride are used per mol of N-alkoxyalkyl-2,6-dialkylaniline of the formula II.

4. A process according to Claim 1 , wherein the reaction of N-alkoxyalkyl-2,6-dialkylaniline of the formula II with chloroacetyl chloride is performed in the temperature range of 700C to the reflux temperature of the reaction mixture.

5. A process according to Claim 1, wherein the reaction of N-alkoxyalkyi-2,6-dialkylaniline of the formula II with chloroacetyl chloride is performed at the reflux temperature of the reaction mixture.

6. A process according to Claim 1, wherein the N-alkoxyalkyl-N-chloroacetyl-2,6-dialkylaniline of the formula I, obtained after removal by distillation of the excess chloroacetyl chloride, is washed at 50 to 1 00C with water.

7. A process according to Claims 1 and 6, wherein there is added to the washing water an amount of alkali sufficient to bring the pH value of the water to 8 to 12.

8. A process according to Claim 1, substantially as hereinbefore described, with reference to the foregoing Example.