Synthesis, crystal, and molecular structures of HIDA and its monomethyl ester

Abstract

A simple procedure for synthesis of HIDA (2,6-dimethylphenylcarbamoylmethyl iminodiacetic acid) is described. It was obtained in better yield by reaction of 2,6-dimethylphenylcarbamoylmethyl chloride with iminodiacetic acid in carbon tetrachloride. The HIDA (A) was identified by IR and¹H NMR spectroscopy. Two types of crystals were detected in the crystal final product. Since they could be separated, the crystals:A andB were investigated by X-ray analysis. Crystal and molecular structures were solved by direct methods and refined by full-matrix least-squares technique toR=0.047 andR=0.056, respectively. In the structure ofA, the N2 atom is protonated and the molecule exists as a zwitterion. The crystal structure of compoundA is stabilized by strong hydrogen bonds, which are reflected in higher close-packing coefficient, density, and melting point, compared to compoundB. CompoundB is a monomethyl ester of HIDA, which is present as an impurity in the final recrystallized product.