The increase in the absorption band at 1755 cm1 was assigned to theC¼O stretching vibration of the carboxylic acid (EDTA acid), and the absorption appearing at 1643 cm1 was assigned to the C¼Oasymmetric stretching vibration of the carboxylic acid. Formation of the carboxylic acid in the products was also confirmed by the typical absorption at 1385 cm1 arising from the carbonyl symmetric stretching vibration