Abstract
Various nitration systems comprising nitric acid, acid anhydride and zeolite H beta in the absence of solvent are described. Direct double nitration of toluene with a nitric acid, propanoic anhydride and zeolite H beta 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-dinitro derivatives. The zeolite can be recovered, regenerated and reused to give almost the same yield as that given when fresh zeolite is used.