Probing new theories of hydrocarbon stability with computational quantum chemistry

CHED 1019

Joel L. Mackey, joellmackey@earthlink.net and Carl R. Kemnitz, ckemnitz@csub.edu. Department of Chemistry, California State University, 9001 Stockdale Hwy, Bakersfield, CA 93311
The origins of the differences in isomeric alkane combustion energies have been a matter of recent debate. It has been argued that geminal steric strain explains the difference between the energy content of isomers. An alternate explanation asserts that the branching of alkanes (“protobranching”) stabilizes one isomer more than another. The energy contents of C1-C8 alkanes were calculated using computational quantum mechanics. Analysis of the computed wavefunctions provides evidence for the destabilizing nature of geminal steric strain but suggests that this strain is not responsible for the greater stability of branched hydrocarbons. Instead, a stabilizing orbital interaction is implicated.