The effect of flexible lattice aluminium in zeolite beta during the nitration of toluene with nitric acid and acetic anhydride
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- Haouas, M., Kogelbauer, A. & Prins, R. Catalysis Letters (2000) 70: 61. doi:10.1023/A:1019015216483
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The nitration of toluene with nitric acid and acetic anhydride using zeolite H‐beta as catalyst was studied with multi‐nuclear solid‐state NMR spectroscopy in order to investigate the causes for the observed enhanced para‐selectivity. The reversible transformation of framework aluminium from a tetrahedral into an octahedral environment was observed by 27Al NMR upon interaction of the zeolite with the different components of the nitrating system. The octahedral co‐ordination complex between lattice aluminium and acetylnitrate might explain the surface‐catalysed para‐selective nitration reaction and suggests that the lattice flexibility plays an important role in determining the regio‐selectivity of the nitration catalysed by zeolites.