[Separation of a mixture of L-isoleucine and L-leucine]

The conditions of L-leucine and L-isoleucine esterification were investigated. It was found that chromatographically homogeneous L-isoleucine and L-leucine could be isolated from their mixture during its incomplete esterification. As a result, L-leucine transformed into L-leucine and ester chlorohydrate L-isoleucine into L-isoleucine chlorohydrate. By means of further neutralization of the reaction mixture L-isoleucine with a 80-85% yield was obtained, and with the aid of L-leucine ester hydrolysis L-leucine with a 80-85% yield was produced. The content of the major amino acid following its crystallization from the water-ethanol mixture was 99%.