A NOVEL METHOD FOR THE NITRATION OF SIMPLE AROMATIC-COMPOUNDS

Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenz enes, and some disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite beta a s a catalyst and a stoichiometric quantity of nitric acid and acetic a nhydride. The zeolite can be recycled, and the only byproduct is aceti c acid, which can be separated easily from the nitration product by di stillation; the process is inexpensive and represents an attractive me thod for the clean synthesis of a range of nitroaromatic compounds. Fo r example, nitration of toluene gives a quantitative yield of mononitr otoluenes, of which 79% is 4-nitrotoluene; fluorobenzene gives a quant itative yield of mononitro compounds, of which 94% is 4-nitrofluoroben zene; and 2-fluorotoluene gives a 96% yield of mononitro products, of which 90% is the 5-nitro isomer and 10% is the 4-nitro isomer.