Molecular structure-property relationships for alkenes

Structure-property relationships were obtained for 11 physical and chemical properties (boiling points (bp), melting points (mp), molar refractions (MR), molar volumes (MV), heats of combustion (HCKJ), molar heats of vaporization (HVMOL), flashpoints (FLASHK), second virial coefficients (VIRC2), critical temperatures (Tc), critical pressures (Pc), and viscosities (VISC)) for a data set consisting of 162 C4-C9 monoalkenes. Both molecular connectivity indices and ad hoc descriptors were tested as structural descriptors, and both produced high-quality regression equations for most of the properties. As was observed in an earlier study of alkanes [J. Am. Chem. Soc. 110 (1988) 4186], mp were not well described by either descriptor set. For most properties, the mass/bulk of the molecule was found to be the most important structural feature determining the property, suggesting that dispersion forces play a dominant role in determining those properties influenced by intermolecular interactions. The amount of branching in the molecule and the nature of the double bond environment were also found to be influential features.