GB857113A - Manufacture of resorcinol - Google Patents

Abstract

A process for the manufacture of resorcinol by the catalytic cleavage of a reaction mixture containing m-di-isopropylbenzene dihydroperoxide derived from the oxidation of m-diisopropylbenzene, comprises heat decomposing the material less volatile than resorcinol while passing steam through said material, simultaneously distilling off the additional quantities of resorcinol and the m-isopropenyl phenol so formed and recovering the resorcinol from the aqueous distillate while maintaining the pH of the latter at a value of at least 4. The pH may be maintained at a value of at least 4, preferably 4-7, by adding a 30% aqueous solution of ammonium sulphate to the cleavage reaction product so as to bring its pH to about 3. This mixture is then distilled to remove acetone and hydrocarbons and the residual aqueous solution distilled in the presence of steam. During this distillation ammonia formed by dissociation of the ammonium sulphate passes over into the distillate and maintains its pH at at least 4. Alternatively ammonium sulphate or a volatile base such as ammonia or an organic amine may be added to the aqueous solution of resorcinol prior to distillation in the presence of steam, or ammonia may be added directly to the distillate. The maintenance of pH at least 4 is said to reduce the tendency of the m-isopropenyl phenol and resorcinol to combine together to form high boiling by-products. A comparative example is given where an aqueous solution of resorcinol of pH 2,2 is steam-stripped to give an aqueous distillate of pH2,8 and where the solution is first neutralised with ammonia to pH 3,9 and then steam-stripped to given an aqueous distillate of pH 4,9 from which improved yields are recovered.