GB148923A - A process for the preparation of nitro compounds of tetrahydronaphthalene and its derivatives - Google Patents

Abstract

The Specification as open to inspection under Sect. 91 (3) (a) states that nitro-compounds of tetrahydronaphthalene may be reduced to the corresponding amino compounds by hydrogen in the presence of a suitable metal or metal oxide. The reduction of dinitro-tetrahydronaphthalene in tetrahydronaphthalene solution is described. This subject-matter does not appear in the Specification as accepted.ALSO:Nitro derivatives of tetrahydronaphthalene are obtained by treating tetrahydronaphthalene with a mixture of nitric and sulphuric acid, or other nitrating mixtures such as nitric acid and acetic acid, containing not more than 25 per cent. of water, the temperature being maintained below 50 DEG C. during the earlier stages of the process. The homologues of tetrahydronaphthalene substituted either in the aromatic or cyclobexane ring by methyl, ethyl, &c. groups, and also the amino or hydroxy derivatives of tetrahydronaphthalene substituted in either ring may be nitrated similarly. Examples are given of the preparation of a mixture of a - and b -mononitrotetrahydronaphthalene, a mixture of dinitrotetrahydronaphthalenes, and a trinitrotetrahydronaphthalene. The dinitro compounds may be used as an ingredient of explosives, in admixture with potassium chlorate, ammonium nitrate, &c. The Specification as open to inspection under Sect. 91 (3) (a) contains also the following subject-matter. On oxidation, the dinitro compound yields 3 : 5-dinitrophthalic acid. Reduction of the nitro-compounds by the usual methods, e.g. by tin or stannous chloride and hydrochloric acid, or by sodium hydrosulphite or by hydrogen in the presence of a catalyst, gives the corresponding amino derivatives of tetrahydronaphthalene etc.; as intermediate stages of reduction may be obtained hydroxylamine, hydrazo, azo, or azoxy compounds, the hydroxylamine derivatives may be rearranged to the p-aminooxy compounds and the hydrazo compounds to the corresponding benzidine derivatives. Examples describe the reduction of the mixture of mononitro compounds to a mixture of a - and b -aminotetrahydronaphthalenes, and of the dinitro compound to the nitroamino compound by sodium hydrosulphide and to the diamino compound by hydrogen in presence of a catalyst. Acetyl compounds of a - and b -aminotetrahydronaphthalenes and benzoyl and benzylidene derivatives of the diamino compound are also described. This subject-matter does not appear in the Specification as accepted.