Poly:dehydro:aspartic acid prodn. from aspartic acid - by heating in high boiling solvent in presence of acid ion exchange resin, intermediates for cosmetic adjuvants

摘要

Prodn. of polydehydroaspartic acid (I) comprises heating aspartic acid (II) in presence of high b.pt. solvent (esp. diphenyl ether) and of a strongly-acid ion-exchange resin at 200-230 degrees C and normal pressure for 2-4 hr. (I) is an intermediate for mixed amide derivs. of polyaspartic acid (see FR 2424292) which are useful as adjuvants in cosmetics. Process gives practically quantitative yields of good coloured prod. and use of diphenyl ether instead of the conventional tetralin reduces reaction time. Solid catalyst makes prod. sepn. easy and the solvent and catalyst can be recycled (up to 5 times without purifcn.).