The thermochemistry, thermodynamic functions, and molecular structures of some cyclic hydrocarbons

Abstract

The following heats of combustion (kilocalories per mole) have been measured via oxygen bomb calorimetry; adamantane (I) (c), -1441.95 ± 0.68; tricyclo[5.2.1.02,6]decane (II) (c), -1460.04 ± 0.60; 1,2,3,4-tetrahydronaphthalene (III) (l), -1342.61 ± 0.51; 1,2,3,4,5,6,7,8-octahydroanthracene (IV) (c), -1902.99 ± 0.69. Vapor pressure curves have been measured for the above compounds and for bicyclo[2.2.1]heptane (V) and bicyclo[2.2.2]octane (VI) which when combined with literature values for the heats of combustion lead to the following gas phase heats for formation (kilocalories per mole); I, -30.65 ± 0.98 (-32.4 ± 0.6, selected value); II, -14.38 ± 0.90; III, 5.29 ± 0.81; IV, -9.01 ± 0.99; V, -12.42 ± 0.70; VI, -23.75 ± 0.30. The heats of formation and strain energies have been calculated by energy minimization using transferable valence potentials and compared with experimental values with satisfactory results. The ideal gas phase thermodynamic functions have been calculated. In a number of cases comparison with experimental entropies is possible. Calculated geometries are also reported.