METHOD OF PREPARING .ALPHA.-L-ASPARTYL-L-PHENYLALANINE METHYL ESTER

摘要

An acid addition salt of .alpha.-APM is dissolved or suspended in an aqueous medium at 50.degree.C or lower at a pH of 3 or less and a concentration of the salt of 3 wt.% or more. A liquid having a pH of 3 or more and containing or not containing .alpha.- APM is prepared and gradually mixed with solution A with stirring. The temperature of the liquid mixture is kept to be 40.degree.C or lower and the pH value of the mixture is kept at 3 or more, optionally adding a base thereto, whereby crystals of .alpha.- APM are precipitated out.