Process of dehydration of nitrilotriacetic acid

Quantum chemistry density functional theory(DFT) on the level of B3LYP/6-311++G(d,p) calculations is used to study the dehydration reaction mechanism of nitrilotriacetic acid(NTA).The corresponding stable configuration was gotten by optimizing the reactants,the transition state and the product,and analyzing the frequency and the natural bond orbital.Frequency analysis results of the transition state show that there is only one virtual band,and it is confirmed by analysis of the vibration and the intrinsic reaction coordinate.The results from the Gaussian03 calculation show that:NTA dehydration reaction as a means of microcosm is NTA→TS→P+H2O.The activation energy required and the energy of the reaction product are 160.206 0 and 68.961 3 kJ/mol,respectively.The reaction is endothermic reaction.The reaction rate constant is calculated to be 5.825×10-16 s-1 using classical transition state theory.