Why Propane?

According to our survey, of all organic compounds propane has the lowest melting point. This exceptional property of propane has been rationalized by the coincidence of light molecular mass, low electrostatic potential, low molecular symmetry as well as a loose arrangement of molecules, unable to match opposite electrostatic potentials on their surface and efficiently fill the space. The main structural features of molecular arrangement persist at least to 6 GPa in propane and n-butane, which we have isothermally and isochorically crystallized in a diamond-anvil cell.