GB754864A - Improvements in and relating to the production of dihydric phenols - Google Patents

Abstract

Dihydric phenols are prepared by decomposing meta- or para-dialkyl benzene dihydroperoxides which are solid at 15 DEG C. or more, by adding sulphuric acid or a solution of sulphuric acid in an inert organic solvent which is also a solvent for the dihydroperoxide to a solution of the dihydroperoxide in the same inert organic solvent, the concentration of the acid by weight being up to 3 per cent of the weight of the reaction mixture and the temperature being maintained at from 0 DEG C. to the boiling point of the reaction mixture. The solvent may be the ketone identical with that liberated during the reaction or the monohydric alcohol corresponding to it and may contain up to 20 per cent by weight of the dihydroperoxide. Water is substantially absent from the reaction mixture which is stirred throughout. Concentrated sulphuric acid of s.g. 1.84 may be used in amounts varying from 0.1 per cent to 0.5 per cent by weight of the reaction mixture and may be dissolved in about 10 per cent of the total inert organic solvent used. The reaction is carried out preferably between 15 DEG and 30 DEG C., under an inert gaseous atmosphere which may be nitrogen or carbon dioxide. The phenols produced are isolated by neutralizing the reaction mixture with solid sodium carbonate, filtering and evaporating the solvent in the presence of marble chips and distilling under an inert atmosphere at ordinary pressure by heating, or under reduced pressure at room temperature. In examples (1) p-di-isopropyl benzene dihydroperoxide in acetone is decomposed with sulphuric acid either alone or in acetone solution under varying conditions of concentration and reaction time, the hydroquinone being isolated as described above under reduced pressure and a carbon dioxide atmosphere; (2) sulphuric acid in isopropanol is added to p-di-isopropyl benzene dihydroperoxide in isopropanol at room temperature, the temperature being raised after addition, the mixture treated with solid sodium carbonate, filtered and evaporated to dryness under reduced pressure with marble chips and under carbon dioxide to give hydroquinone which is recovered by sublimation; (3) sulphuric acid in acetone is added to a mixture of m- and p-di-isopropyl benzene dihydroperoxides in acetone at room temperature, the temperature raised after addition and the mixed dihydric phenols isolated as described in (2). Specification 684,039 is referred to.