Hydrochlorination and hydrobromination of N-(N-arylsulfonylbenzimidoyl)-1,4-benzoquinonimines

The direction of hydrohalogenation of N-substituted p-quinonimines was pred icted on the basis of orbital coefficients of the C-2 and C-3 atoms in the lowest unoccupied molecular orbital, calculated by the PM3 method. It was a ssumed that the reaction is orbital-controlled and that the initial act of hydrohalogenation is nucleophilic attack by halide ion. The proposed approa ch was verified by experimental hydrochlorination and hydrobromination of N -(N-arylsulfonylbenzimidoyl)-1,4-benzoquinonimines which take up HHlg molec ule following the 1,4-addition scheme, i.e., the halogen atom adds to C-2 o f the quinoid ring.