ja953858a_si_002.pdf (701.29 kB)
Unimolecular Isomerizations and Oxygen Atom Loss in Formaldehyde and Acetaldehyde Carbonyl Oxides. A Theoretical Investigation
journal contribution
posted on 1996-05-15, 00:00 authored by Josep M. Anglada, Josep M. Bofill, Santiago Olivella, Albert SoléThe lowest singlet and triplet potential energy surfaces of
formaldehyde carbonyl oxide (1) and
acetaldehyde
carbonyl oxide (2) have been investigated in the regions
concerning the most relevant unimolecular reactions by
means of CASSCF and MRDCI ab initio quantum-chemical calculations.
The questions related to the mechanism
of O-atom loss from carbonyl oxides, as well as the competition between
the cyclization to dioxirane and the
tautomerization to hydroperoxide in methyl-substituted carbonyl oxides
are addressed in this investigation. The
theoretical predictions are consistent with experimental findings
obtained from stopped-flow studies of the gas-phase ozonation of both trans-butene and tetramethylethylene.
An unexpected result is that the most reasonable
pathway for O-atom loss from “hot” singlet carbonyl oxides
1 and 2 involves internal rotation about the CO
bond
axis, followed by intersystem crossing to the lowest triplet state and
subsequent scission of the OO bond.