CS277482B6 - Halogencarboxylic acids benzyl esters preparation process - Google Patents

Abstract

Halocarboxylic esters of general carboxylic acids of formula I X - CO - O - CH 2 - C 6 H 5 (1), wherein X is chloromethyl, bromomethyl, 2- chloroethyl, 2-bromoethyl, 1-chloroethyl or 1-bromoethyl, are prepared by reaction of the appropriate halo carboxylic acid with benzyl alcohol v the presence of a catalyst selected from the group consisting of including p-toluenesulfonic sulfur and phosphates acid, in the middle! inert organic solvents with a boiling point of up to 100 ° C, (q) forming with the reaction water an azeotropic mixture, the zinc used in an amount of 15 to 50% W by weight based on the reaction weight mixture, at the reflux temperature of the reaction mixture. ei The solution can be used in the production of chemical plant protection products.

Description

The invention relates to a process for the preparation of benzyl esters of halocarboxylic acids. These compounds are known as intermediates for the production of chemical plant protection products.

Several methods for preparing benzyl esters of halocarboxylic acids are known from the literature and from industrial practice. The process according to PL 45 791 is based on the reaction of a halocarboxylic acid with a molar excess of benzyl chloride at a temperature of 140 to 200 ° C, which is difficult to handle from a technological point of view and does not provide sufficient yields and the required degree of product purity. Methods using the reaction of halogenated carboxylic acid chlorides, e.g. chloroacetyl chloride with benzyl alcohol in the presence of / Helv. chim. Acta 42., 1214-24, 1959 / or absence / Ž. Obšč. Chem. 26, 1471-82, 1956 / target, amine as an acceptor of the resulting hydrogen chloride require economically and ecologically demanding synthesis of the starting carboxylic acid chlorides, which limits the possibility of their use on an industrial scale. Finally, methods for preparing benzyl esters of halocarboxylic acids by reacting a halocarboxylic acid, e.g. chloroacetic acid with benzyl alcohol in the presence of hydrogen chloride / Ber. 21, 282, 1988 / or in the presence of dichloromethane and in the presence of 2-chloro-1-methylpyridinium iodide and tributylamine [Bull. Chem. Soc. Jap. 50/7 /, 1863-6, 1977 / provide low yields of the final product, resp. they are demanding in terms of the required reactants.

The process for the preparation of benzyl esters of halocarboxylic acids of the general formula I eliminates these disadvantages to a decisive extent.

WHAT

(1) wherein X is chloromethyl, bromomethyl, 2-chloroethyl, 2-bromomethyl, 1-chloroethyl or 1-bromomethyl, by reaction of a halocarboxylic acid of formula II

X - C - OH (11) wherein X is as defined above with the benzyl alcohol according to the invention. The invention is carried out in the presence of a catalyst selected from the group consisting of p-toluenesulfonic acid, sulfuric acid and phosphoric acid in an inert organic solvent boiling up to 100 ° C, forming an azeotropic mixture with the water of reaction used in in an amount of 15 to 50% by weight, based on the weight of the reaction mixture. Cyclohexane or benzene is preferably used as the inert organic solvent. The process can be carried out batchwise or continuously.

The advantages of the process for the preparation of benzyl esters of halocarboxylic acids of the formula I according to the invention over known processes are, in particular, that they are technologically unpretentious, operate at relatively low reaction temperatures and give a high purity product (purity above 98%) in yields above 96%.

The following examples illustrate but do not limit the scope of the invention.

Example 1

To 692 g (6.4 mol) of benzyl alcohol dissolved in 800 cm ^{3 of} benzene, 12 g of p-toluenesulfonic acid and 600 g (6.35 mol) of chloroacetic acid were added with stirring, and the reaction mixture was heated with stirring. After reaching reflux, 114 cm of water formed azeotically separated off the reaction. The reaction mixture was cooled, washed with 200 cm ^{3 of} 5% aqueous sodium carbonate solution and 300 cm ^{3 of} water, and after azeotropic drying, benzene was distilled off under a slight vacuum. The residue (1175 g) was then distilled off under reduced pressure to give 1021 g of chloroacetic acid benzyl ester as a colorless liquid, b.p. 94-96 ° C / 106.6 Pa, corresponding to a yield of 87.1%.

Example 2

To 346 g (3.2 mol) of benzyl alcohol dissolved in 400 cm ^{3 of} cyclohexane were added 6 g of sulfuric acid and 300 g (3.175 mol) of chloroacetic acid with stirring, the reaction mixture was heated to reflux with stirring and then azeotroped. cm ^{3 of} reaction water. Work-up of the resulting reaction mixture as described in Example 1 gave 569 g of crude product which was distilled to give 552 g of benzyl chloroacetic acid, b.p. 94-96 ° C / 106.6 Pa, corresponding to a yield of 94%.

Example 3

21.6 g (0.2 mol) of benzyl alcohol, 21.7 g (0.2 mol) of 2-chloropropionic acid and 0.3 g of phosphoric acid were added to 100 cm ^{3 of cyclohexane with stirring, and the mixture was stirred and stirred.} taking water of reaction (3.6 cm ³ ) was heated to reflux. After cooling, the reaction mixture was washed with 50 ^cm3 of 5% aqueous sodium uhlicxtanu be a solution with 100 ^cc of water, azeotropically dried under vacuum and was distilled cyclohexane. Distillation of the residue (40 g) gave 35.2 g of 2-chloropropionic acid benzyl ester, b.p. 146 DEG-147 DEG C. (1.6 kPa), corresponding to a yield of 88.6%.

Example 4 O

To 200 ^cc of cyclohexane was added with stirring 30.6 g / 0.2 mole / of 1-bromopropionate, 21.6 g / 0.2 mol /) benzyl alcohol and 0.3 g of p-toluenesulfonic acid, the mixture is stirred was heated to reflux while azeotropically distilling off the reaction water (3.6 g) and worked up as in Example 3. 48 g of crude product were obtained, which by distillation gave 43.8 g of 1-bromopropionic acid benzyl ester, b.p. 86 ° C / 53.3 Pa, which corresponds to a yield of 90.1%.

Claims (2)

A process for the preparation of benzyl esters of halocarboxylic acids of the general formula I X - C - O - CH ₉ - CcHc | X - C - OH Wherein X is as defined above with benzyl alcohol, characterized in that the reaction is carried out in the presence of a catalyst selected from the group consisting of p-toluenesulfonic acid, sulfuric acid and phosphoric acid in an inert organic solvent boiling to 100 ° C, forming an azeotropic mixture with the water of reaction, used in an amount of 15 to 50% by weight, based on. by weight of the reaction mixture, at the reflux temperature of the reaction mixture. 2. The process according to item 1, characterized in that cyclohexane or benzene is used as the inert organic solvent. End of document