In a 100 ml-volume flask, 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 were placed, and the mixture was reacted under heating at 230° C. for one hour in a nitrogen stream. After the reaction, the system was cooled to room temperature, the reaction mixture was dissolved in 50 ml of toluene, insoluble matters were filtered and the filtrate was purified by silica gel column chromatography using toluene to obtain 19.6 g of N,N'-diphenyl-N,N'-bis[3-(2-ethoxycarbonylethyl)phenyl]-[1,1'-biphenyl]-4,4'-diamine as an oily substance. The IR spectrum of the product is shown in FIG. 2.
