Regioselective dinitration of simple aromatics over zeolite Hβ/nitric acid/acid anhydride systems
Smith, Keith . 2014
Abstract:
Various nitration systems comprising nitric acid, acid anhydride and zeolite Hβ in the absence of solvent are described. Direct double nitration of toluene over a nitric acid, propanoic anhydride and zeolite Hβ system has been developed to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6 dinitrotoluene ratio of 123:1. This system also nitrates activated mono-substituted benzenes (anisole and phenetole) and moderately activated mono-substituted benzenes (ethylbenzene and propylbenzene) to give mainly 2,4-dinito derivatives. The zeolite can be recovered, regenerated and reused to give almost the same yield as that given when fresh zeolite is used.
Key word:
Dinitration, acid anhydride, propionic anhydride, propanoyl nitrate, mono-substituted benzenes, zeolite Hβ, regioselectivity
