| 摘要 |
2,2 - (2,41 - Dihydroxy - diphenyl) - propane is isomerized into 2,2-(4,41-dihydroxy-diphenyl)-propane by a process comprising: (a) maintaining a mixture of the isomers in an environment of phenol containing dissolved hydrogen chloride at a temperature to keep a substantial part of the mixture in the solid phase for a period which allows the relative proportions of the isomers to achieve substantially equilibrium by isomerization, the initial proportion of 2,2-(2,41-dihydroxydiphenyl)-propane in the mixture being greater than the equilibrium proportion at the said temperature; (b) applying a vacuum to the reactor and rapidly removing the hydrogen chloride from the isomers at increasing temperature; and (c) separating phenol from the isomers by distillation. The process makes possible the reduction of large proportions of the contaminating orthopara polymer in the para-para compound to much smaller proportions. The process is preferably carried out at a temperature not exceeding 60 DEG C. with as small a proportion of phenol to polymers as possible, preferably 2-3 moles per mole of polymer. The process is particularly applicable to the treatment of diphenylol propane obtained by the condensation of acetone with phenol.
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