1, 4-Cyclohexadiene Synthesis by Metathesis of 1, 4-Hexadiene over a CsNO3-Re2O7-Al2O3 Catalyst in Liquid Phase

The synthesis of 1, 4-cyclohexadiene(1, 4-CHD) by metathesis of 1, 4-hexadiene was investigated. The reaction was carried out using a continuous-flow system over a CsNO3-Re2O7-Al2O3 catalyst in the liquid phase at atmospheric pressure. The catalyst appeared to be very active and selective for the metathesis. All the reaction products were metathesis products except small amounts of benzene, cyclohexene and 1, 3-CHD. 1, 4-CHD could be obtained with a yield of 50% per pass under such mild reaction conditions as 60°C and W/F: 6g-cat•h/mol. It is considered that 1, 4-CHD synthesis by the metathesis is superior to the known processes and it provides a new effective method. Furthermore, the pathways of the formation of reaction products and a reaction scheme have been discussed in detail.