EQUILIBRIUM STUDIES OF COPPER(2) COMPLEXES OF IMINODIACETATES WITH AMINO ACID ESTERS AND KINETICS OF ESTER HYDROLYSIS

Formation constants for the interaction of various amino acids, HA, and amino acid esters, E, with a series of substituted iminodiacetate (RN(CHR′CO2)(CH2CO2)2-) complexes of Cu(II), Cu(RIMDA), indicate there are steric repulsions between bulky R groups of the substituted iminodiacetates and large groups on the esters. The amino acid esters in the complexes, Cu(IMDA)(E), hydrolyze with rates of hydrolysis decreasing in the order: MeGly > MeAla > EtSar > EtGly > BuGly > EtLeu. No hydrolysis is observed near pH 7 for esters such as ethylbetaine and N-benzoylglycine methyl ester which do not complex appreciably with Cu(IMDA). The equilibrium and kinetic data are consistent with the reactions[formula omitted] In the case of catalysis by Cu(IMDA), there is evidence that the last step also proceeds partially by H2O attack. In both the OH- and H2O attack mechanisms it is assumed that the ester group is directly coordinated to the metal ion when the nucleophilic attack occurs. The rates of hydrolysis in Cu(RIMDA)(E) depend relatively little upon the nature of R except when R contains a coordinating group. © 1969, American Chemical Society. All rights reserved.