Diels-Alder Addition of Dicyclopentadiene with Cyclopentadiene in Polar Solvents

Diels-Alder addition of dicyclopentadiene and cyclopentadiene in polar solvents has been studied to produce tricyclopentadiene(TCPD)that is a potential high-density fuel precursor.GC and MS analysis shows that the adducts contain two isomers,namely exo-and endo-TCPD.Theoretical simulation shows that although the transition state of endo-TCPD has a lower activation energy,exo-TCPD is thermodynamically preferred.Polar solvents can accelerate the reaction rate and improve the exo/endo ratio of TCPD because the transition state of exo-TCPD has a higher polarity than that of endo-TCPD.The solvent effect follows the order of polarity:benzyl methanol＞cyclohexanone＞toluene.The conversion rises when the temperature ranges from 120 to 150℃,but the selectivity of TCPD slightly decreases.Increasing the pressure Can improve the conversion but the exo/endo ratio of TCPD is unchanged.The apparent kinetics in different solvents was determined via nonlinear regression.The activation energies are 99.47,101.15,and 107.32 kJ/mol for benzyl methanol,cyclohexanone,and toluene,respectively.The optimal reaction conditions are as follows:benzyl methanol as solvent,temperature 150℃,and pressure 900kPa.After an 11-hour reaction,a conversion of 58.O%,a TCPD selectivity of 95.7%, and an exo/endo ratio of 1/5.3 has been obtained.