Towards an intrinsic nucleofugality scale: The leaving group (LG) ability in CH3LG model system

For an important class of organic reactions in which a fragment of the reactants, the leaving group (LG) or nucleofuge (Z), is detached of the substrate bearing the bonding electron pair, the global electrophilicity index of the CH3LG system is proposed as a reliable descriptor of the intrinsic nucleofugality of the LG. The model is illustrated by ranking within a unique relative scale, the LG ability of 28 functional groups commonly involved in substitution and elimination reactions in organic chemistry.