Regioselectivity of the Liquid-phase Mononitration of Weakly Activated Arenes Over Cross-linked Clays

Methodology of a selection and environmental economy in nitration reaction of aromatics will be rather attractive to replace traditional sulfonitric acid process in industry. The cross-linked pillared clays originated from a natural bentonite show an obviously selective catalysis in nitration reaction of alkylbenzenes by respectively using nitric acid and a nitrogen dioxide/molecular oxygen system when compared with Kyodai-nitration. Several hydroxyl-aluminum cross-linked bentonites (Al-CLB, NH4Al-CLB, HAl-CLB, LaAl- CLB) were prepared in various conditions from a natural bentonite with polymeric cationic complexes of aluminum as pillars or crosslinkers. When they were applied in the nitration of weakly activated aromatic substrates, a para-preferential nitration is achieved.