ENTHALPY OF ISOMERIZATION OF QUADRICYCLANE TO NORBORNADIENE

Using a closed-bomb reaction calorimeter, the enthalpy of isomerizatio n of quadricyclane (QC) to norbornadiene (NBD) in a benzene solution h as been measured at room temperature in the presence of HgBr2. In the pure liquid states, a value of -89.03 +/- 1.18 kJ mol-1 was obtained. From the enthalpies of vaporization of QC and NBD measured using a vap orization calorimeter (37.85 +/- 0.04 and 34.83 +/- 0.10 kJ mol-1, res pectively), the gaseous enthalpy of isomerization was also derived as -92.05 +/- 1.18 kJ mol-1.