Patent ID: 7728149

Claim:
A process for producing a dicarboxylic acid comprising the step of subjecting a cycloalkane to an oxidative cleavage reaction with oxygen in the presence of a catalyst comprising: a divalent or trivalent cobalt compound; or a divalent or trivalent cobalt compound and an imide compound having at least one cyclic imide skeleton represented by the following Formula (1) wherein n is 0 or 1; and X is an oxygen atom or a —OR group, wherein R is a hydrogen atom or a hydroxyl-protecting group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are the same or different and are each one selected from the group consisting of a hydrogen atom, halogen atoms, alkyl groups, aryl groups, cycloalkyl groups, hydroxyl groups, alkoxy groups, carboxyl groups, substituted oxycarbonyl groups, acyl groups, and acyloxy groups, wherein at least two of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 may be combined to form one of a double bond, an aromatic ring and a non-aromatic ring, and wherein one or more of the N-substituted cyclic imido groups indicated in Formula (1) may be formed on at least one of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 and/or on the double bond, aromatic ring or non-aromatic ring formed by the at least two of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 , in a liquid phase using a continuous reactor to thereby yield a corresponding dicarboxylic acid, wherein the residence time τ (hr) satisfies the following condition: 0.1≦τ≦50 /c wherein c is the proportion (% by weight) of the cycloalkane to the total weight of a charged liquid, with c being equal to or more than 25% by weight.