Thermal, photochemical, and photophysical processes in cyclopropanone vapor

Thermochemistry and kinetics of acetonylperoxy radical isomerisation and decomposition: a quantum chemistry and CVT/SCT approach

“…The same holds true for cyclopropanone where the atomisation value of 19.2 kJ mol À1 compares well with an experimental value of 16 AE 4 kJ mol À1 . 70 As a further check the computed enthalpy of reaction for the transformation of oxetan-3-one to b-propiolactone: of À99.9 kJ mol À1 is in quite good agreement with the difference in enthalpies of formation 71 of À96.8 kJ mol À1 .…”

Ring strain energy and enthalpy of formation of oxiranone: an ab initio theoretical determination

“…The value of 16 ± 4 kJ mol Ϫ1 , adopted in the above discussion of isodesmic reaction (2), was obtained by Thomas and coworkers 26 from measurements of the appearance potential for the C 2 H 4 ϩ ion formed from cyclopropanone by electron impact in a mass spectrometer. Evaluation of ∆H o f,298 (10) by this method requires a known value for ∆H o f,298 (C 2 H 4 ϩ CO); use of more recent thermochemical data, 31 together with the appearance potential (9.69 eV) of Thomas and co-workers, 26 yields a value for ∆H o f,298 (10) of 21 kJ mol Ϫ1 rather than 16 kJ mol Ϫ1 .…”

The photodissociation of solvated cyclopropanone and its hydrate explored via non-adiabatic molecular dynamics using ΔSCF

“…10,11 Based on the rapid photolysis with a reaction time of ≤200 ps, a predissociation process to a biradical was proposed, in contrast to the intersystem crossing mechanism of other cyclic ketones. 9,12 The excitation to the 1 (n→π*) state weakens the lateral C–C bond ( i.e. the C–C bond adjacent to the carbonyl group) strength of the already strained cyclopropanone resulting in the asymmetric dissociation.…”

“…After the first few experimental studies, several types of computational investigations on the photodissociation of a cyclopropanone molecule were performed as well. 9–11,13–15 A minimum-energy conical intersection (MECI) near the first singlet excited state (S 1 ) minimum promoting ultrafast internal conversion was identified with complete active space self-consistent field (CASSCF) calculations. 10 Upon excitation to the S 1 state, a fast non-radiative relaxation process, internal conversion and dissociation in the ground state were observed using non-adiabatic molecular dynamics (NAMD).…”

“… 8 An experimental study of the gas-phase photochemistry yielded ethylene, carbon monoxide and polymers as photoproducts. 9 However, polycyclopropanone was formed in negligible amounts and was ascribed to the thermal reaction. Fluorescence was observed only at wavelengths above 365 nm.…”