The Nitration of 3,4,5,6-Tetramethylbenzene-1,2-Dicarbonitrile, 2,3,5,6-Tetramethylbenzonitrile, 1,2,3-Trimethyl-4,6-Dinitrobenzene and 1,2,4,5-Tetramethyl-3,6-Dinitrobenzene. Methyl Migrations Following ipso-Substitution

Abstract

Nitration of 3,4,5,6-tetramethylbenzene-1,2-dicarbonitrile (1a) gives epimeric pairs of dinitro ketones (6a) and (7a), and hydroxy ketones (9) and (10), in addition to the benzyl nitrate (4) and phthalide (5). Nitration of 2,3,5,6-tetramethylbenzonitrile (11) gives the epimeric dinitro ketones (15) and (16), in addition to the nitrobenzonitrile (12) and the nitrophthalide (13). Nitration of 1,2,3-trimethyl-4,6- dinitrobenzene (17) gives dimethylpropanedioic acid (23), the dinitrobenzoic acid (24), and the hydroxy dienone (25). Nitration of 1,2,4,5-tetramethyl-3,6-dinitrobenzene (18) gives dimethylpropanedioic acid (23), the dinitrobenzoic acid (26), and the nitro dicarboxylic acid (27). The formation of compounds (6a),(7a),(9),(10),(15),(16),(23) and (27) all involve methyl migrations following nitronium ion attack ipso to the migrating methyl group. X-Ray structure determinations are reported for compounds (6a), (9) and (15).