Process for the preparation of dinitro-polyalkylbenzenes

Claim 1

A process for the preparation of a dinitro-polyalkylbenze of the formula ##STR5## in which R 1 and R 2 , independently of each other, denote straight-chain or branched C 1 -C 8 -alkyl, R 3 represents hydrogen, straight-chain or branched C 1 -C 4 -alkyl and R 4 denotes hydrogen, straight-chain or branched C 1 -C 4 -alkyl chlorine or bromine, where, in the absence of chlorine or bromine, the total number of the alkyl C atoms is at least 4, by nitration of a polyalkylbenzene of the formula ##STR6## in which R 1 to R 4 have the meanings given, a solid being produced during the reaction, using HNO 3 in the presence of H 2 SO 4 , wherein a) sulphuric acid of 81 to 96% by weight strength is introduced as reaction medium, without the accompanying use of an organic solvent, in an amount of from 180 to 1000 g per mole of polyalkylbenzene; at least 30% of the sulphuric acid amount being introduced prior to the introduction of any reactants, b) the polyalkylbenzene, 95 to 100% strength by weight HNO 3 and any remaining sulphuric acid are fed simultaneously in the range of from 0° to 60° C., in such manner that the added substances polyalkylbenzene and HNO 3 , during addition, are in the molar ratio of 1:2-10, c) after the addition, the reaction mixture is kept at 10 to 70° C. for further reaction and d) the dinitro-polyalkylbenzene is separated from the reaction mixture.