Patent ID: 7183437

Claim:
A method for preparing three types of benzidine compounds: in an equivalent ratio of compound 4: compound 5: compound 6 of (86″3%):(13″2%):(0.2–1.5%), the method comprising reacting compound 1, compound 2 and compound 3: where compound 1 is a first diphenylamine compound, compound 2 is a second diphenylamine compound, and compound 3 is a biphenyldihalide compound, in the presence of an additive at 100–200° C., to produce a mixture of compound 4, compound 5 and compound 6 in said equivalent ratio, wherein the additive comprises an organic metallic compound, an inorganic alkali, and a ligand wherein compound 1, compound 2 and compound 3 are reacted in an equivalent ratio of compound 1: compound 2: compound 3 of (1):(11″0.3):(5″0.3), and the reacting takes place in a solvent selected from the group consisting of benzene, ether, ethanol, a cyanoalkane and mixtures thereof; and R 1 and R 2 are selected from the group consisting of hydrogen, an alkyl group containing 1–5 carbons, an alkoxy group containing 1–5 carbons and benzene; X is selected from the group consisting of chlorine, bromine, and iodine; and Y is selected from the group consisting of chlorine, bromine, and iodine.