Into a 100 ml flask were placed 10.77 g of N,N'-diphenylbenzidine, 23.0 g of ethyl 3-iododihydrocinnamate, 11.61 g of potassium carbonate, 1.0 g of copper sulfate pentahydrate, and 20 ml of n-tridecane, and they were thermally reacted under an atmosphere of N2 at 230° C. for 1 hour. After the reaction, the reaction mixture was cooled down to room temperature, dissolved in 50 ml of toluene, the insolubles were filtered, and the filtrate was purified by silica gel chromatography using toluene. This gave 19.6 g of N,N'-diphenyl-N,N'-bis[3-(2-ethoxycarbonylethyl)phenyl]-[1,1'-biphenyl]-4,4'-diamine in an oily state.
