Patent ID: 6939993

Claim:
A method for separating a reaction product from an imide compound catalyst represented by Formula (1) or an altered derivative thereof in a reaction mixture obtained as a result of a reaction in the presence of the imide compound catalyst, the method comprising the step of performing an extraction process using two organic solvents separable from each other, one of said solvents being a nonpolar organic solvent and another of said solvents being a polar organic solvent, to thereby separate the reaction product into a nonpolar organic solvent layer and the imide compound catalyst or an altered derivative thereof into a polar organic solvent layer, respectively: wherein R 1 and R 2 are the same or different and are each a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cycloalkyl group, a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, or an acyl group, where R 1 and R 2 may be combined to form a double bond, an aromatic ring, or a non-aromatic ring; X is an oxygen atom or a hydroxyl group; and one or two of an N-substituted cyclic imido group indicated in the formula may be further formed on R 1 , R 2 , or on the double bond, aromatic ring, or non-aromatic ring formed by R 1 and R 2 .