| Abstract: | The esterification of ethylenediaminetetraacetic acid (EDTA) in a hot acidic medium gives rise to impure products. The impurities have been identified and shown to be esters of various acids: nitrilotriacetic acid; iminodiacetic acid; piperazine-1,4-diacetic acid; N-methylethylenediaminetriacetic acid; N,N- and N,N′-dimethylethylenediaminediacetic acids and 2-ketopiperazine-1,4-diacetic acid. The reactions for the formation of these impurities are discussed and a method for the preparation of pure esters of EDTA is described. Details of some crystalline derivatives, 1H-n.m.r. and infrared spectra of a series of esters of EDTA are presented. The determination of the molecular weights of the esters by saponification is discussed. |
