| 摘要 |
PURPOSE:To optically resolve DL-alanine under a stable condition economically advantageously and readily in preferentially crystalliziing alanine as a benzenesulfonate, by using water as a resolving solvent in the presence of a strong acid. CONSTITUTION:DL-Alanine or alanine wherein one active substance of D- or L-alanine exists in excess is preferentially crystallized as a benzenesulfonate. In the operation, the alanine is dissolved in an aqueous solution of a strong acid such as methanesulfonic acid, etc., under heating and then cooled. Crystal of an optically active alanine benzenesulfonate is seeded in the aqueous solution and crystal of the same kind of active salt is crystallized at 0-50 deg.C. Crystal of an optically active alanine benzenesulfonate having optical activity opposite to the crystal is seeded in the aqueous solution supplied with the DL-alanine benzenesulfonate and crystallized. These operations are repeatedly carried out to give the aimed substance. A different amino acid such as serine, etc., may be simultaneously present in the crystallization solution. The optically active alanine is useful as a food additive or a raw material for synthesizing peptide.
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