Process for the preparation of a crystalline L-MGDA trialkali metal salt

摘要

A process is proposed for the preparation of a crystalline L-MGDA trialkali metal salt by crystallization from an aqueous solution thereof which has been obtained by Strecker synthesis, starting from L-α-alanine, by reaction with formaldehyde and hydrocyanic acid to give L-α-alanine-N,N-diacetonitrile and subsequent alkaline saponification of the L-α-alanine-N,N-diacetonitrile to give the L-MGDA trialkali metal salt, wherein a temperature of 150° C. is not exceeded during the alkaline saponification.

主权项

1. A process for preparing a crystalline L-MGDA trialkali metal salt, the process comprising:
(1) reacting enantiomerically enriched L-α-alanine with formaldehyde and hydrocyanic acid to give L-α-alanine-N,N-diacetonitrile; then (2) saponifying the L-α-alanine-N,N-diacetonitrile under alkaline conditions to give a L-MGDA trialkali metal salt; and (3) crystallizing the L-MGDA trialkyl metal salt from an aqueous solution, wherein a temperature of 150° C. is not exceeded during the saponifying (2) so that the L-MGDA trialkali metal salt does not racemize, and the L-MGDA trialkali metal salt is a L-MGDA trisodium salt or a L-MGDA tripotassium salt.