A-Chloropropionic acid

Nitroethane may be similarly obtained from sodium a chloropropionate. This is a general reaction for a chloro carboxylic acids, but in practice only monochloroacetic acid and a chloropropionic acid are readily available. 

Laboratory synthesis yields a racemic mixture. When a compound containing an asymmetric carbon atom is synthesised in the laboratory from a compound that has none, the product is always a racemic mixture. Thus if a chloropropionic acid is prepared from propionic acid a racemic mixture results ... 

Alanine was prepared in i860 by Kolbe by the second general method, by the action of ammonia upon a-chloropropionic acid —... 

A highly asymmetric induction in the nickel-catalyzed electroreductive couplings of aryl halides with a-chloropropionic acid derivatives was reported by Nedelec and coworkers [Eq, (65)] [495]. 

Recent works in asymmetric induction has yielded two new ways (1) the electroenzymatic reduction [179, 180] and (2) the use of oreganometallic complexes as mediators (like complexes of Ni11, Pd11, or Co11 [181, 182]. For example, nickel-catalyzed cross coupling between aryl halides and a-chloropropionic acid derivatives bearing chiral auxiliaries affords arylpropionates in high yield and excellent enantiomeric excess [183],... 

Optically active esters of a-chloropropionic acid are precursors of agrochemical compounds. These esters are prepared from lactic acid using the synthesis path described in Figure 1. D-Iactic acid is obtained by fermentation. Initially, this compound was esterified to methyl lactate which itself was transformed to (L) methyl chloropropionate (a-CPM). The content of the minority enantiomer in these three compounds was of between 1.5 and 2.5%. 

Fig. 1. Diagram representing the synthesis of esters of a-chloropropionic acid from lactic acid...

Two methods using GC on chiral stationary phases were developed. Both enabled direct analysis of the two esters of a-chloropropionic acid. 

Dichlorprop is prepared by the condensation of 2,4 dichlorophenol and a-chloropropionic acid, or by the chlorination of a-phenoxypropionic acid. The technical product is a 1 1 mixture of the biologically active dextrorotatory ( +) isomer and the biologically inactive levorotatory (-) isomer. Its biological action was first reported by Zimmermann and Hitchcock (1944), but it was only introduced in 1961. 

The acid mecoprop (9) is prepared by the condensation of />-chloro-o-cresol with a-chloropropionic acid. Stevenson and Brooks recommended the following alternative route of synthesis (1959) ... 

Thiolaetic Acid 2 Afercaptopropanoic acid 2-merCaptOprOpionic acid 2 -thio]propionic acid ocmercapto-propanoic acid, CjH OjS mol wt 106,14, C 33.95%, H 5.70%, O 30.14%, S 30.21%, CH3CH(SH)COOH. First prepd from a-chloropropionic acid and potassium hydrosul -fide Schacht,, 4nn. 129, 3 (1864) prepn from ot-chloropro-pionic acid and sodium thiosulfate Martin, U.. pat. 

Alanine, CH3.CHNH2.COOH, a-aminopropiomc acid, may be prepared by the action of ammonia on a-chloropropionic acid. It is an important decomposition-product of proteins. Serine which is the jS-hydroxyl derivative of alanine, is also obtained from proteins. It has been synthesized from glycollic aldehyde by the reactions indicated in the second method of preparing amino-acids described above (334). 

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