PROCESS FOR PRODUCING 3,3',5,5'-TETRAALKYL-4,4'-BIPHENOL

摘要

An industrially advantageous process for producing a tetraalkylbiphenol (TABP) in which an unreacted dialkylphenol (DAP) can be repeatedly recovered and reused. The process comprises: a step (A) in which a DAP is oxidatively dimerized with an oxygenic gas in the presence of a water solvent and a metallic catalyst to obtain an aqueous slurry which comprises a liquid reaction mixture containing the unreacted DAP, the metallic catalyst, and an aromatic aldehyde as an impurity and a TABP dispersed in the mixture; and a step (B) in which the TABP is separated from the resultant aqueous slurry by solid-liquid separation. In the process, the aqueous slurry and/or the aqueous liquid reaction mixture recovered in the step (B) is distilled to recover an azeotropic mixture comprising water and the unreacted DAP, and part of the recovered fraction containing the aromatic aldehyde is supplied to the oxidative dimerization to regulate the amount of the aromatic aldehyde contained in a feed reaction mixture so as to be up to 60 times by mole the amount of the metallic catalyst therein.