Nitration of 2, 5-Dimetyl-1-acylbenzenes with Fuming Nitric Acid/Acetic Anhydride System Effects on the Ring Substituents o n the Formation of the 2-Nitromethyl-1-acylbenzenes

Abstract

2, 5-Dimethylacetophenones 1 and 2, 5-dimethylbenzophenones 2 with a variety of substituents (H, CH₃, OCH₃, Cl) have been reacted with fuming nitric acid in acetic anhydride to give the corresponding 2-(nitromethyl)acetophenones 3 and 2-(nitromethyl)benzophenones 4, respectively. The nitration of the compounds 1 and 2 bearing methyl or methoxyl groups at the 4-position has afforded the corresponding 3 and 4 in high yields. The nitration of compounds unsubstituted at the 4-position gave the products of a complex mixture. The compounds 1 and 2 with the highest HOMO electron density at the 5-position (according to MNDO calculations) have been selectively nitrated to lead to the compounds 3 and 4.