| abstract |
PURPOSE: To recover the titled compound useful as a low-caloric sweetening agent, by adding a basic substance to an aqueous solution containing at least 3-benzyl-6- carboxymethyl-2,5-diketopiperazine as an impurity, and by crystallizing the titled compound. n CONSTITUTION: A basic substance, e.g. NaOH, is added to an aqueous solution of an α-L-aspartyl-L-phenylalanine lower alkyl ester(α-APE) containing at least 3-benzyl-6-carboxymethyl-2,5-diketopiperazine (DKP) as an impurity to crystallize and recover the isolated α-APE. Preferably, the pH of the aqueous solution is kept at 4.5W8 after the addition of the basic substance at a relatively high temperature, and the crystals are deposited most efficiently by cooling the mixture immediately after the addition. n EFFECT: DKP which cannot be effectively removed by the conventional recrystallization method can be readily eliminated. n COPYRIGHT: (C)1980,JPO&Japio |