Process for the preparation of (L)-2-chloropropionic acid and it

Details Process for the preparation of (L)-2-chloropropionic acid and it Process for the preparation of (L)-2-chloropropionic acid and it

1996-02-15

1998-05-19

Marx, Irene

Chemistry: molecular biology and microbiology

Process of utilizing an enzyme or micro-organism to destroy...

Resolution of optical isomers or purification of organic...

435141, 435198, C12P 752

Patent

active

057534950

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a novel process for preparing (L)-2-chloropropionic acid and its alkali metal, alkaline earth metal or ammonium salts.
JP 57 094 295, JP 62 205 797, EP-A 196 625, JP 61 111 699 and Appl. Biochem. Biotechnol. 9(3) (1984) 255 disclose the enantio-selective enzymatic cleavage of racemic 2-chloropropionic esters. However, the disadvantage in this case is, besides the maximum possible yield of only 50%, the insufficient enantiomeric purity of the 2-chloropropionates formed.
Furthermore, EP-A 257 716 discloses a continuous process in which methyl D,L-2-bromopropionate is used as racemate and converted in a 2-phase system using Candida cylindracea lipase into methyl L-(-)-2-bromopropionate. However, no hydrolysis products are isolated in this process.
Furthermore, S. K. Dahod and P. Sinta-Mangano describe in Biotechnol. Bioeng. 30(8) (1987) 995 the lipase-catalyzed hydrolysis of methyl L-2-chloropropionate in the presence of carbon tetrachloride. However, the disadvantage in this case is, besides the use of a chlorinated solvent, the low yield of about 30% with an enantiomeric purity of only 95%.
In addition, EP-A 511 526 teaches a process for the enzymatic hydrolysis of racemic 2-chloropropionic esters in a 2-phase system which consists of water and of an organic solvent, which is substantially immiscible with water, for the ester. This process is very elaborate because it is necessary several times for the organic phase to be separated off, brought into contact with the hydrolase and recycled again. Since, despite relatively long reaction times, only incomplete conversion takes place and enantiomerically pure products are not obtained, this method is unsuitable for the industrial preparation of (L)-2-chloropropionic acid and its sodium salt.
Sodium (L)-2-chloropropionate and (L)-2-chloropropionic acid have to date been prepared by alkaline hydrolysis of isobutyl (L)-2-chloropropionate. However, this often results in a low-quality product (about 90-95% enantiomeric excess) which additionally contains 5-10% lactic acid as by-product.
Thus, the object of the present invention was a simple process for preparing (L)-2-chloropropionic acid and sodium (L)-2-chloropropionate of maximum chemical and optical purity (at least about 98% enantiomeric excess and less than 1% lactic acid).
Accordingly, a process for the preparation of (L)-2-chloropropionic acid and its alkali metal, alkaline earth metal or ammonium salts was found which comprises hydrolyzing isobutyl L-chloropropionate at a pH of from 4 to 8 in the presence of a lipase from Pseudomonas spec. DSM 8246*) and isolating the optically active reaction product from the reaction mixture either directly or after conversion of the salt into the acid in a conventional way, or further reacting it in situ. Pseudomonas sp. DSM 8246 was deposited with the DSM on Apr. 28, 1993, and was assigned the accession number DSM 8246 by this International Depository Authority. Mascheroder Weg 1B, 38124 Braunschweig
Isobutyl L-chloropropionate is advantageously prepared starting from D-lactic acid which can be prepared, for example, by a biotechnological process disclosed in EP-A 069 291. This entails a mixture of aqueous glucose solution, yeast autolysate, vitamins, catalytic amounts of phosphoric acid and a buffer for the lactic acid produced, e.g. calcium carbonate, being fermented at about 45.degree. C. with the addition of lactic acid bacteria. The pH of the fermentation broth is preferably 4-6. A lactate is produced with evolution of carbon dioxide and is converted into D-lactic acid by adding an acid, preferably concentrated aqueous sulfuric acid. The D-lactic acid is subsequently extracted with isobutanol. The resulting D-lactic acid solution is then concentrated. Part of the lactic acid is esterified even during this. The remaining amount of lactic acid is esterified with acid catalysis, sulfuric acid being an example of a suitable acid (cf., for example, EP-A 287 426, DE-A 32 14 697 and DE-A 34 33 400). The water formed in the reaction is subs

REFERENCES:
patent: 4668628 (1987-05-01), Dahod et al.
patent: 5278054 (1994-01-01), Buchner et al.
Cambou et al., App. Biochem. and Biotech., vol. 9, 1984, pp. 255-260.
Dahod et al., Biotech. & Bioeng., vol. 30, No. 5, Oct. 5, 1987.

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