Regioselectivity of reduction of 1,3-dinitrobenzene with potassium (sodium) tetrahydridoborate and electronic structure of reagents and their complexes

Abstract

Reaction of 1,3-dinitrobenzene with the tetrahydridoborate ion was studied by means semiempirical PM3 calculations in the isolated molecule and reactant complex approximations. The deviation of the nitro groups from the benzene ring plane, resulting from their rotation about the C3N bond, changes the reaction pathway from the preferred aromatic ring reduction to nitro group reduction. On this basis an explanation of published data on the effect of the temperature and the polarity of the medium on the regioselectivity of the reaction is offered.