The general procedure for the synthesis of 1,8-octanediamine from 1,6-dicyanohexane was as follows: a 500 mL autoclave was assembled with a thermocouple thermometer, a stirrer (two-piece tilting paddle), a pressure gauge, and a hydrogen purge line. To the autoclave were added 175 g of 1,6-dicyanohexane, 86.0 g of methanol, 2.0 g of 28% sodium methacrylate-methanol solution (0.64% w/w), and 10.5 g of nickel catalyst (based on nickel monomers, which accounted for 6.0 w/w% of 1,6-dicyanohexane). The water content of the solution was 920 ppm at this point, as measured by a Karl Fischer hydrometer (manufactured by Hiranuma Sangyo Co., Ltd.) Upon completion of the dosing, hydrogen substitution was performed, and then the pressure was increased to 5 MPa. The temperature was raised to an internal temperature of 90 °C, and the ramping process lasted for approximately 1 hour. Hydrogen consumption was observed from about 70°C. The reaction was started at 90°C and hydrogen consumption essentially stopped after about 6 hours. After continuing the reaction for 2 hours, the reaction was cooled to room temperature, depressurized, and the reaction solution was filtered to remove the catalyst and the filtrate was washed with 100 g of methanol. The total weight of the 1,8-diaminooctane methanol reaction solution obtained was 377.4 g. The area of 1,8-diaminooctane was analyzed by GC to be 94.3% and the reaction yield was 96.7%.
