Lipoic acid → alpha Lipoic acid

Participants

Reaction Conditions

Reaction Steps

A solution which contained 19.5 g R-(+)-thioctic acid and 0.5 g S-(-)-thioctic acid in a mixture of 24 ml toluene and 6 ml n-heptane was cooled off from 35 to 40° C. down to -5 to -10° C., filtered and dried. 13.0 g thioctic acid were obtained in the novel modification as first crystallizate. The R-(+)-thioctic acid content was 94.5% with a melting range of 45 to 48° C.

Provenance & Evidence