1-Cyanomethyl-4-carboxymethyl-3-ketopiperazin, salte deraf og en fremgangsmåde til fremstilling af disse forbindelser

A novel intermediate useful in the synthesis of ethylenediaminetriacetic acid (ED3A) or its salts. N,N'-ethylenediaminediacetic acid (ED2AH2) or a salt containing up to one equivalent of base cation is condensed with formaldehyde to form a stable cyclic intermediate. The addition of cyanide forms 1-cyanomethyl-4-carboxymethyl-3-keto-piperazine or a salt thereof (mononitrile-monoacid), which is a useful intermediate in the production of ED3A. The nitrile in aqueous solutions may be hydrolysed to form 2-oxo-1,4-piperazinediacetic acid (3KP) or salts thereof. In the presence of excess base, salts of ED3A are formed in excellent yield and purity.