Zeolite-mediated regioselective nitration of phenol in solid state

Phenol (1) is nitrated regioselectively by fuming nitric acid inside the cages of faujasite zeolites. While nitration as hexane slurry in CsY and molecular sieve 5 A leads to predominant formation of para-nitrophenol (III), a remarkable ortho-selectivity is observed in solid state nitration to yield exclusively ortho-nitrophenol (II). Loading level of the substrate inside the supercage alters significantly the relative yield of the various products. Other advantage of this zeolite-mediated nitration include significant reduction in polynitration and absence of mixed nitrating agents. (C) 2002 Elsevier Science B.V. All rights reserved.