OPTICAL RESOLUTION OF DL-VALINE, DL-LEUCINE, AND DL-ISOLEUCINE BY FORMATION OF ADDUCT WITH L-PHENYLALANINE.

Article abstract of DOI:10.1246/bcsj.57.2234

An alkaline solution containing L-phenylalanine (L-Phe) and one of DL-leucine, and DL-isoleucine is allowed to selectively form a precipitate composed of L-Phe and the aliphatic D-amino acid by adjusting the pH of initial solution to around 5. 5 with hydrochloric acid **1H NMR spectra in deuterium oxide, elemental analyses, and infrared spectra of the precipitates indicate that they are adducts of the aliphatic D-amino acid and L-Phe in the molar ratio of 1:1. The free aliphatic D-amino acids with high optical purity (84-100%) may be recovered fromthe adducts in 49-63% yield. An attempt was made to obtain both the aliphatic D- and L-amino acids by using an aqueous solution containing the aliphatic DL-amino acid and L-Phe as an initial solution.