The nitration of styrenes by nitric acid in dichloromethane

Abstract

Kinetics and products of reaction of 4-R-styrenes (R = Me, H, Cl, CF₃, NO₂) with nitric acid in dichloromethane are reported. Reaction occurs in the alkene group and aromatic nitration is insignificant. With increasingly electron-withdrawing substituents the reaction changes from one which is third order in nitric acid and gives rise to the 1-arylethyl nitrate, to one which is of higher order in nitric acid and gives rise to the 2-nitro-1-arylethyl nitrate (β-nitro-nitrate). Both reactions proceed through transition states with carbocation character, by initial β-addition of H⁺ and NO₂⁺ respectively. The β-nitro-nitrate is formed in part also by a radical pathway, as are other minor products.