DFT study of the formation of a-chloro-pyruvic esters from α- chloroglycidic esters isomers

In this work,we studied the ring opening mechanism of α-chloroglycidic esters in the presence of lewis acid mgcl2.this reaction mechanism leads to the formation of chloro-pyruvic esters. our theoretical study was carried out in the solvated phase using density functional theory at the b3lyp/6-31g (d) level. the geometric structures at the various stationary points on a part of this reaction path were fully optimized. the theoretical calculations of the different energy levels were in agreement with the experimental data. a study of the potential energy surface allowed to identify different molecular complexes associated with the approach reaction of the lewis acid on the α- chloro glycidic ester preceding the formation of the transition structures. in order to account for the molecular mechanism,we calculated the wiberg index for the transition states and pyruvic products using natural bond orbital analysis (nbo). for a better interpretation of our reaction mechanism,we calculated the percentage of evolution of the bonds that break and form (% ev) along our chemical process. the results allowed to verify that the reaction mechanism is concerted,which is in good agreement with previous experimental results. © 2017,university of mohammed premier oujda morocco.