NITRATION OF 2,5-DIMETHYL-1-ACYLBENZENES WITH FUMING NITRIC-ACID ACETIC-ANHYDRIDE SYSTEM - EFFECTS ON THE RING SUBSTITUENTS ON THE FORMATION OF THE 2-NITROMETHYL-1-ACYLBENZENES

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.