Theoretical study of the methylic reactivity of substituted alkenes

A PM3/UHF study of the methylic reactivity of a series of about fifty alkenes was carried out. Several MP2/6-31G^** ab initio calculations were made for comparison. The semi-empirical method of calculation is proven to give good estimates of the reactivity under consideration. The computations brought to light the reactivity enhancement of alkenes when substituted on the same carbon of the double bond, whereas a lessening is observed when both carbons are substituted. An interpretation in terms of deformation (DEF) and interaction (INT) energies is made. Contrarily to phenyl, the vinyl group improves notably the reactivity of methylated and chlorinated mono or disubstituted alkenes. The prediction is made for the reactivity of more than fifteen compounds which were not studied experimentally.