Thermochemical Properties and Bond Dissociation Energies of C1–C4 Chloroperoxyalkanes

Abstract Reactions of chlorine atoms with hydrocarbons are among the most important oxidation processes in Earth’s atmosphere. However, only limited information is available on the thermochemical properties of chloroperoxyalkane (ROOCl) species. In this work, the thermochemical properties of C1–C4 chloroperoxyalkanes were determined based on density functional theory and ab initio methods. Internal rotations, optimized structures, vibrational frequencies, and moments of inertia of the target species were identified and determined. Standard enthalpies of formation at 298 K, ΔfH°298, were calculated at the M06-2X, ωB97XD, CBS-QB3, and G4 levels of theory. Several isodesmic work reactions were used to evaluate the ΔfH°298 values, which are reported together with their uncertainties at the 95% confidence limit. Entropy at 298 K and temperature-dependent heat capacities (300–1500 K) were reported. The ROO–Cl bond dissociation energies (BDEs) are slightly higher than the corresponding RO–OCl BDEs. Reported ΔfH°298 values in kcal mol–1 obtained from the most stable structures are CH3OOCl (0.28 ± 0.37), CH3CH2OOCl (−7.96 ± 0.27), CH3CH2CH2OOCl (−12.82 ± 0.23), CH3CHOOClCH3 (−17.26 ± 0.21), CH3CH2CH2CH2OOCl (−17.85 ± 0.25), (CH3)3COOCl (−25.64 ± 0.17), (CH3)2CHCH2OOCl (−19.24 ± 0.22), and CH3CHOOClCH2CH3 (−22.37 ± 0.22). The thermochemical group parameter O/Cl/O, used in the group additivity method, was also developed in this study.