GB2055802A - Process for the preparation of the optical isomers of alpha -chloro (or bromo) propionic acid esters - Google Patents
Process for the preparation of the optical isomers of alpha -chloro (or bromo) propionic acid esters Download PDFInfo
- Publication number
- GB2055802A GB2055802A GB8015218A GB8015218A GB2055802A GB 2055802 A GB2055802 A GB 2055802A GB 8015218 A GB8015218 A GB 8015218A GB 8015218 A GB8015218 A GB 8015218A GB 2055802 A GB2055802 A GB 2055802A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bromo
- chloro
- propionic acid
- alpha
- acid esters
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/62—Halogen-containing esters
- C07C69/63—Halogen-containing esters of saturated acids
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
A process for the preparation of the individual optical isomers of alpha - chloro- (or bromo-) propionic acid esters, which comprises reacting an (L)- lactic acid ester with thionyl chloride (or bromide) (a) in the presence of a base to give a (D)- alpha -chloro- (or bromo-) propionic acid ester or (b) in the absence of a base to give an (L)- alpha -chloro-(or bromo-) propionic acid ester. The products are useful as intermediates in the synthesis of certain herbicides.
Description
SPECIFICATION
Chemical process
This invention relates to a chemical process for the preparation of optically active a-halopropionic acid esters and their conversion to optically active a-phenoxy-propionic acid esters.
According to the present invention there is provided a process for the preparation of the individual optical isomers of a-chloro-(or bromo-)propionic acid esters which comprises reacting an (L)-lactic acid ester with thionyl chloride (or bromide) (a) in the presence of a base to give a (D)-a-chloro-(or bromo-)propionic acid ester or (b) in the absence of a base to give an (L)-a-chloro-(or bromo-)propionic acid ester.
(L)-Lactic acid is a cheap material available from natural sources. Consequently either (D)- or (L)-o-halopropionic acid esters may readily be obtained by the above-defined process, which is illustrated in the following scheme:
cOOH COOR N C > R.OZ b HOW H 3 cE3 (L)-Lactic acid soci2 / ( SOBr ) SoOlvbase (SOBr2) C5O5r/case) / COOR COOR C' C H ci Cl (Br) (Br)Cl ClI3 3 The radical R of the alcohol R.OH which is used to esterifythe (L)-lactic acid may be any radical which is inert towards the reaction conditions of the lactic acid ester with thionyl chloride.Preferably R is an alkyl radical containing from 1 to 4 carbon atoms, e.g. methyl, ethyl, n-propyl, iso-propyl or one of the isomeric butyl radicals.
In the case in which the reaction of the lactic acid ester with thionyl halide is carried out in the presence of a base, the latter may be, for example, a tertiary amine such as pyridine.
Certain of the (D)- or (L)-halopropionic acid esters which are obtainable according to the above-defined process are valuable intermediates in the synthesis of certain herbicides such as are described in, for example, UK Patent Specification No. 1491274. Thus, the (D)- or (L)-a-chloropropionic acid butyl ester may be brominated under conditions which either lead to retention or inversion of configuration to give a (D)- or (L)-a-bromo-a-chloropropionic acid butyl ester. Similarly (D)- or (L)-a-bromopropionic acid butyl ester may be chlorinated. The a-bromine atom in these compounds is more reactive than the a-chlorine atom, and reaction with hydroquinone in the presence of a suitable acid binding agent yields a compound having the structure:
which on further reaction with, for example, 2-chloro-5-trifluoromethyl pyridine, followed by reductive replacement of the a-chlorine atom by hydrogen, yields and (D)- or (L)-isomer of the compound:
which is a valuable herbicide. Since the (D)- and (L)- isomers of such compounds are not equally active for all applications, the present invention provides a simple method for synthesis of the desired optically pure isomer.
Claims (5)
1. A process for the preparation of the individual optical isomers of a-chloro-(or bromo-)propionic acid esters which comprises reacting an (L)-lactic acid ester with thionyl chloride (or bromide) (a) in the presence of a base to give a (D)-a-chloro- (or bromo-)propionic acid ester of (b) in the absence of a base to give an (L)-a-chloro- (or bromo-)propionic acid ester.
2. A process as claimed in claim 1 wherein the (L)-lactic acid ester is an ester of (L)-lactic acid with an alcohol R.OH in which the radical R is an alkyl radical containing from 1 to 4 carbon atoms.
3. A process as claimed in claim 1 or claim 2 wherein, when the reaction is carried out in the presence of a base, the base is a tertiary amine.
4. A process as claimed in claim 3 wherein the tertiary amine is pyridine.
5. (D)- or (L)-a-chloro- (or bromo-)propionic acid esters whenever obtained by a process as claimed in any one of the preceding claims.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8015218A GB2055802A (en) | 1979-08-07 | 1980-05-08 | Process for the preparation of the optical isomers of alpha -chloro (or bromo) propionic acid esters |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7927409 | 1979-08-07 | ||
| GB8015218A GB2055802A (en) | 1979-08-07 | 1980-05-08 | Process for the preparation of the optical isomers of alpha -chloro (or bromo) propionic acid esters |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2055802A true GB2055802A (en) | 1981-03-11 |
Family
ID=26272448
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8015218A Withdrawn GB2055802A (en) | 1979-08-07 | 1980-05-08 | Process for the preparation of the optical isomers of alpha -chloro (or bromo) propionic acid esters |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2055802A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0056981A1 (en) * | 1981-01-27 | 1982-08-04 | Hoechst Aktiengesellschaft | Process for the preparation of optically active 2-chloropropionic acid esters |
| EP0163435A2 (en) * | 1984-05-23 | 1985-12-04 | Imperial Chemical Industries Plc | Preparation of 2-chloropropionic acid esters |
| US4601987A (en) * | 1985-02-27 | 1986-07-22 | Massachusetts Institute Of Technology | Enzymatic production of optical isomers of 2-halopropionic acids |
| EP2052607A1 (en) | 2007-10-24 | 2009-04-29 | Bayer CropScience AG | Herbicide combination |
| DE102008037622A1 (en) | 2008-08-14 | 2010-02-25 | Bayer Cropscience Ag | Herbicide combination with dimethoxytriazinyl-substituted difluoromethanesulfonylanilides |
| CN101935273A (en) * | 2010-09-07 | 2011-01-05 | 南通诚信氨基酸有限公司 | Method for preparing high-purity S-2-chloropropionic acid |
| US11352311B1 (en) * | 2021-06-27 | 2022-06-07 | Bomi Patel-Framroze | Single-step stereospecific synthesis of (S)-2-chloropropionic acid alkyl ester |
-
1980
- 1980-05-08 GB GB8015218A patent/GB2055802A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0056981A1 (en) * | 1981-01-27 | 1982-08-04 | Hoechst Aktiengesellschaft | Process for the preparation of optically active 2-chloropropionic acid esters |
| EP0163435A2 (en) * | 1984-05-23 | 1985-12-04 | Imperial Chemical Industries Plc | Preparation of 2-chloropropionic acid esters |
| EP0163435A3 (en) * | 1984-05-23 | 1987-01-07 | Imperial Chemical Industries Plc | Preparation of 2-chloropropionic acid esters |
| US4601987A (en) * | 1985-02-27 | 1986-07-22 | Massachusetts Institute Of Technology | Enzymatic production of optical isomers of 2-halopropionic acids |
| EP2052607A1 (en) | 2007-10-24 | 2009-04-29 | Bayer CropScience AG | Herbicide combination |
| DE102008037622A1 (en) | 2008-08-14 | 2010-02-25 | Bayer Cropscience Ag | Herbicide combination with dimethoxytriazinyl-substituted difluoromethanesulfonylanilides |
| CN101935273A (en) * | 2010-09-07 | 2011-01-05 | 南通诚信氨基酸有限公司 | Method for preparing high-purity S-2-chloropropionic acid |
| US11352311B1 (en) * | 2021-06-27 | 2022-06-07 | Bomi Patel-Framroze | Single-step stereospecific synthesis of (S)-2-chloropropionic acid alkyl ester |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |