Patent ID: 6218573
Filing Date: 2001-04-17
Classification: C07C,Y02P

Abstract:
A method of treating a reaction mixture produced by direct oxidation of cyclohexane to adipic acid, the reaction mixture comprising a monobasic acid solvent having only primary and/or secondary hydrogen atoms, water, and a catalyst, the method being characterized by steps of:(a) removing a major part of the monobasic acid solvent;(b) adding water and a first constituent, the first constituent being substantially non-solvent for the catalyst, in such quantities so as to form or maintain a homogeneous solids-free single liquid phase in absence of the major part of the monobasic acid solvent at a desired first temperature;(c) extracting with water a major part of the catalyst contained in the homogeneous solids-free single liquid phase, thus forming a solids-free aqueous liquid phase containing the major part of the catalyst, and a solids-free non-aqueous liquid phase; and(d) separating the solids-free aqueous liquid phase from the solids-free non-aqueous liquid phase;wherein steps (a) and (b) are not necessarily sequential.