New thermochemical reference system expressing the relative energy of organic compounds

To facilitate the comparison of the energies of nonisomeric organic compounds, we introduce a new thermochemical reference system. The reference substances, instead of elements, are series of compounds: unbranched alkanes and their selected derivatives (halogenides, ethers, sulfides, and tertiary amines). The relative enthalpies calculated from the heats of formation directly reflect the relative energy of both isomeric and nonisomeric compounds, and they can be used in the calculation of the heats of reaction. The relative enthalpies of the elements (in kJ/mol) are C, –22.846; H₂, 43.426; O₂, 251.66; N₂, –178.62; S, –41.62; F₂, 396.12; C1₂, 94.22; Br₂, 8.16; and I₂, –107.64.