JPS6157534A - Preparation of optically active 2-chloropropionic acid ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an intermediate of an optically active phenoxypropionic acid pesticide, etc., in high yield and purity, by decomposing an optically active 2-chlorosulfinoxypropionic acid ester with a specific catalyst. CONSTITUTION:The objective compound of formula II can be prepared by decomposing the optically active 2-chlorosulfinoxypropionic acid ester of formula I (R is 1-4C alkyl) at 60-100 deg.C using a decomposition catalyst consisting of a polar aprotic compound such as phosphoric acid hexamethyltriamide, dimethylformamide, tetramethylurea, etc. The amount of the catalyst is about 5X10<-3>mol per 1mol of the compound of formula I. The starting compound of formula I can be synthesized by reacting D- or L-lactic acid ester with thionyl chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a method for producing optically active 2-chloropropionic acid ester by decomposing optically active 2-chlorosulfine oxypropionic acid ester.

[Conventional technology and problems]

The optically active 2-chloropropionic acid ester, which is the object of the present invention, is a J! Necessary intermediates are produced. It is already known that optically active 2-chloropropionic acid ester can be obtained from optically active lactic acid ester and equimolar amounts of pyridine and thionyl chloride.

(W, Genard ez & l, J, Org,
Ohem, 8, 401(1y43)) According to this method, starting from D-lactic acid ethyl ester,
L-2-chloropropionic acid ethyl ester with an optical purity of 90% was obtained in a yield of only 70%, which is not suitable for industrial production. It is also known to decompose chlorsulfine oxypropionic acid ester, which is a reaction product of lactic acid ester and thionyl chloride, using a catalytic amount of pyridine to obtain 2-chloropropionic acid ester. (B,
Liebermannex &1. ．． Nature
, 160.903 (1947), W.

Genard ez al, Nature, 15
9. (1947)), however, although this method achieves a chemical yield of about 95%, it yields 2-chloropropionic acid ester with an optical purity of only about 55%, making it unsuitable for industrial production.

[Problem 'f: Means to solve]

As a result of extensive studies, the present inventor discovered that optically active D- or L-
When chlorsulfine oxypropionate, which is a reaction product of lactic acid ester and thionyl chloride, is decomposed in the presence of a specific catalyst, the corresponding L- or D-2- is produced, respectively.
It was discovered that chloropropionic acid ester can be obtained in high yield and high optical purity, and the present invention was achieved. 0jOH-00OR (in the formula, R means an alkyl group containing 1 to 6 carbon atoms). It is produced by the decomposition of optically active 2-lysulfine oxyprobionic acid ester, which has the same meaning as . The present invention relates to a method for producing active 2-chloropropionic acid ester.

In the process according to the invention D- or L-2- of formula I
Chlorsulfine oxypropionate is continuously added dropwise to a heated reactor containing a decomposition catalyst. On the other hand, at the same time, the by-product sulfur dioxide is discharged out of the system.

Any polar aprotic compound may be used as the decomposition catalyst, but examples include phosphoric acid hexamethyltriamide, dimethylformamide, dimethyl, ruacetamide, and tetramethylurea. Among these, phosphoric acid Hexamethyltriamide is preferably used. The amount of catalyst to be used is approximately 5.times.10-'mole per mole of chlorsulfine oxypropionic acid ester, and the use of more than this amount is economically disadvantageous.

The reaction is carried out while maintaining the temperature of the reactor at 60 to 100°C. The decomposition reaction occurs at temperatures above 50°C, but below 60°C the reaction is slow, and above 100°C the optical purity of the product deteriorates. The pressure may be normal pressure or reduced pressure.

The D- or L-2-chlorosulfine oxypropionate ester of formula I used in the reaction can be prepared according to known methods (
Houban-4agl, Volume ■/2゜431 pages]D
- or L-lactic acid ester and thionyl chloride.

Simultaneously with or after the decomposition reaction, the produced 2-chloropropionic acid ester is separated and purified from the decomposition catalyst, unreacted thionyl chloride, a small amount of dissolved sulfur dioxide, etc. by distillation.

The yield of optically active 2-chloropropionic acid ester is 95
~98% yields a product with an optical purity of 95-98% or higher.

〔Example〕

The present invention will be explained in more detail with reference to the following examples.

Reference example (synthesis of starting material 2-chlorosulfine oxypropionate) 1.0 mol of L- or D-lactic ester was added to 1A-1,0
The mixture was added dropwise to 5-1-l of thionyl chloride while stirring at room temperature. Since hydrogen chloride is generated at this time, the reactor is equipped with a detoxification device. After the dropwise addition was completed, the mixture was left at the same temperature for 12 hours, and then used for the decomposition reaction.

The 7'CL- or D-2-chlorosulfine oxypropionate thus obtained can be used without particular purification.

Example 1 Into a reactor equipped with a dropping funnel and an alkali canister for absorbing sulfur dioxide, 0.5 liters of phosphorous hexamethyltriamide was added.
Heat the crude D-2-chlorosulfine oxypropion methyl ester 6 a, 9.9 (
According to the method described on the reference side [α]3°=-)-5,52@
0) produced by reacting 0.377-al of D-lactic acid methyl ester was added dropwise over about 2 hours. After the addition was completed, the pressure was reduced to 50 zw and simple distillation was carried out.
,30=-26,4"0 L-2-chlorophyhionic acid methyl ester was obtained in an amount of 45.51. The yield was 98.2% based on D-lactic acid methyl ester.

Example 2 Into a reactor equipped with a dropping funnel, a Liebig e1m vessel, a receiver and an alkali absorption can, 0.75 l of phosphoric acid hexamethylene triamide was added, heated to 65°C, and crude D was added under a reduced pressure of 50 zow. -2-Chlorsulfine oxyglopionic acid methyl ester 172.2 J (Produced by reacting 0.945 mol of D-lactic acid methyl ester with [α] = +B, 52° according to the method described on the reference side.) was added dropwise over a period of about 2 hours, and simultaneously produced mu-2-chloropropionyl methyl ester was distilled out together with sulfur dioxide.

After simple distillation, [a]i' knee 26.5° L-2-
Methyl chloropropionate ft110.91 obtained ◇D-
The yield based on lactic acid methyl ester was 96.2%.90 Example 3 The reaction was carried out in the same manner as in Example 1 except that 1.0 I of dimethylformamide was used as the decomposition catalyst. a] Mu-2-chloropropionic acid methyl ester t-as,ql of 6°a=-25.8° was obtained. The yield based on D-lactic acid methyl ester was 95.1%.Example 4 D-lactic acid ethyl ester ([α]ru' = -1-1o
, a'), except that the reaction was carried out in the same manner as in Example 1, and after simple distillation [a) I of 6°==-18,5°
, -2-chloroprobionic acid ethyl ester"fc48
．． I got 91. Yield based on D-lactic acid ethyl ester is 95
．． It was 4%.

Incidentally, the optical purity of the 7'C2-chloropropionic acid ester obtained in the above examples was all 98% or higher.

Fu delivery agent, Kaoru Furuya

Claims (1)

[Claims] 1. Optical activity 2- represented by formula I ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R means an alkyl group containing 1 to 6 carbon atoms.) Chlorpropionate is converted into a chloropropionate by decomposition of an optically active 2-chlorosulfine oxypropionate ester represented by the formula II ▲Mathematical formula, chemical formula, table, etc.▼(II) (in the formula, R has the same meaning as in formula I) A method for producing optically active 2-chloropropionic acid ester, which is characterized in that a polar aprotic compound is used as a decomposition catalyst in the production. 2. The polar aprotic compound is hexamethyltriamide phosphate, dimethylformamide, dimethylacetamide. or tetramethylurea, the manufacturing method according to claim 1.