CS253435B1 - Process for preparing 2-chloracrylic acid - Google Patents

Abstract

The present invention relates to a process for preparing 2-chloroacrylic acids of the formula Ar-CH = CCl-COOH where Ar is phenyl, o-, m-, p-nitrophenyl, 2-nitrofuryl, 2-nitrocenyl, 2-bromo-furyl, 2-bromothienyl, furyl, thienyl. Its essence lies in the fact that the aryl or heteroacylidenemalonic acid is chlorine in organic solvents in water or mixtures thereof temperature of 5 to 150 ° C.

Description

The invention relates to a process for the preparation of 2-chloroacrylic acids of the formula I

COOH

FROM

Ar — CH = C \

Cl ¹ (I) wherein

Ar is phenyl, o-, m-, p-nitrophenyl (Newman MS: Org. React 5, 426 (1949)). The essence of the process for the preparation of 2-chloroacrylic acids according to the invention is based on the aryl or heteroarylidenemalonic acids of the formula II

COOH

FROM

Ar — CH = C \

COOH (Π) where

2-nitrofuryl

2-nitrotienyl

O, WAr as defined above is treated with chlorine in the environment of organic solvents from the group of halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, bromoform, organic acids such as acetic acid, propionic acid, in carbon disulphide, Ν, Ν-dimethylformamide and in water or mixtures thereof at a temperature of 5 to 150 ° C.

The reaction proceeds according to the following scheme:

COOH

2-brómfuryl

Ar — CH = C + Cl2 \

COOH

2-bromothienyl

S 'furyl

2-chloroacrylic acids are important chemical intermediates for the synthesis of acetylenes, polymers, 2-amino acids, etc. Their preparation is carried out by various mainly halogenation and dehalogenation reactions (Houben-Weyl, Methoden der Organischen Chemie, Band V / 4, Stuttgart 1960) as well as by condensation, such as e.g. Wittig reaction (Johnson A.W. Ylid Chemistry, Acad. Press, NY and London (1966)). In Darzen's synthesis, they are formed as by-products

COOH

FROM

- »Ar — CH = C \

Cl

... / / + CO HC HCý.

wherein Ar is as defined above.

Said method of preparation is energy-efficient and produces products of high purity and high yields of virtually quantitative yields.

The by-products of the reaction are carbon dioxide and hydrogen chloride, which are gaseous under the given conditions.

Example 1 g of 4-nitrobenzilidene malonic acid was dissolved in 200 ml of acetic acid and added simultaneously to 10 g of chlorine in 100 ml of acetic acid. The reaction mixture was heated at boiling for 2 h. After distilling off the solvent, 23 g of 2-chloro-3- (4-nitrophenylacrylic acid, m.p. 197-202 ° C) were obtained.

25.5 g of 5-nitro-2-thienylidenemalone acid were suspended in 200 ml of chloroform and added to 10 g of chlorine in 200 ml of chloroform. After 2 hours heating at boiling point the solvent was distilled off under vacuum. 27 g of 2-chloro-3- (5-nitro-2-thienyl) -acrylic acid of m.p. 252-254 ° C were obtained.

Example 3 g of 5-nitro-2-furfurylidene malonic acid was suspended in 100 ml of 1,2-dichloroethane and added to 10 g of chlorine in 100 ml of 1,2-dichloroethane. After 2 hours heating at boiling point the solvent was distilled off under vacuum. 25 g of 2-chloro-3- (5-nitro-2-furyl) acrylic acid of m.p. t. 252 - 254 degrees Celsius.

Claims (1)

Process for preparing 2-chloroacrylic acids of formula I COOH FROM Ar -, CH = C \ Cl (I) where Ar is phenyl, o-, m-, p-nitrophenyl, 2-nitrofuryl, 2-nitrophenyl, 2-bromofuryl, 2-bromothienyl, furyl, thienyl, characterized in that to aryl or heteroarylidene malonic acids of formula II INVENTION COOH FROM Ar — CH = C \ COOH (Π) where Ar is as defined above and is treated with chlorine in the environment of organic solvents from the group of halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, bromoform, organic acids such as acetic acid, propionic acid, etc. in carbon disulphide, Ν, Ν-dimethylformamide and in water or mixtures thereof at a temperature of 5 to 150 ° C.