Abstraction and addition reactions of four γ-lactones with H-atoms and methyl radicals

The five-membered cyclic esters, or γ-lactones, are promising candidates as biofuel additives and green solvent components. A comprehensive study of thermochemical and kinetic properties of γ-butyrolactone (GBL), γ-valerolactone (GVL), γ-caprolactone (GCL), and γ-heptalactone (GHL) has been conducted. The entropy, specific heat, enthalpy function, and the enthalphy of formation at 298.15 K, as well as the adiabatic ionization potential and single bond dissociation energies are reported. Bimolecular rate constants for the abstraction of H-atom by H^• and CH (Formula presented.) are presented on a per abstractable hydrogen basis; abstraction at the tertiary carbon site is consistently favored, while abstraction by CH (Formula presented.) lags behind H^•. Addition reactions of H^• and CH (Formula presented.) have high barriers and favor addition to the C-center.