GB320397A - Improvements in the manufacture and production of n-dihydro-1.2.2.1-anthraquinoneazine fast to chlorine - Google Patents

Abstract

320,397. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.): July 11, 1928. Anthraquinonehydroazines. - N-dihydro-1 : 2 : 2<1> : 1<1>-anthraquinoneazines fast to chlorine are obtained by treating an impure N-dihydro-1 : 2 : 2<1> : 1<1>-anthranquinoneazine, or a methyl derivative or sulphonic 'acid thereof, with manganese dioxide or other higher oxides of manganese in sulphuric acid. The sulphuric acid used may contain up to 33 per cent of water, or weak oleum may be employed. By this treatment the impurities causing the lack of fastness to chlorine are destroyed, while the N-dihydro-1 : 2 : 2<1>: 1<1>- anthraquinoneazine is practically unaffected. The process is particularly suitable for the treatment of the mixture of dyestuffs obtained by alkali fusion of 2-aminoanthraquinone, as described, for example, in Specification 3239/01, and for this purpose it is unnecessary to separate the dyestuff B referred to in Specification 22762/01. The purity of the product can be further improved by choosing energetic conditions for the production of the crude dyestuff mixture, such as lengthening the time of fusion, or by passing air over during the fusion. The process is also suitable for the further working up of the products obtained by the process of Specification 296,106. The products, which are obtained first in the form of azines, may be reduced to the hydroazines in the known manner, for example by dissolving in sulphuric acid and treating with phenols. In example, (1) commercially pure indanthrone, or the dyestuffs obtainable according to Specification 3239/01 and 296,106, while increasing the duration of the alkali fusion, are treated with sulphuric acid of various strengths and artificial manganese dioxide or pyrolusite, (2) 3 : 3<1>-dimethyl - N - dihydro-1 : 2 : 2<1> : 1<1>-anthraquinoneazine is similarly treated, and (3) Indanthrene blue R.S. is sulphonated with a mixture of boric and sulphuric acids, the sulphonation mixture is treated with a suspension of pyrolusite in sulphuric acids, and the product obtained reduced to the hydroazine by treating with a reducing agent, such as crude carbolic acid, in sulphuric acid. Specification 23875/09 and 184,193 also are referred to.