title: A novel and facile decay path of Criegee intermediates by intramolecular insertion reactions via roaming transition states.
abstract: We have discovered a new and highly competitive product channel in the unimolecular decay process for small Criegee intermediates, CH2OO and anti/syn-CH3C(H)OO, occurring by intramolecular insertion reactions via a roaming-like transition state (TS) based on quantum-chemical calculations. Our results show that in the decomposition of CH2OO and anti-CH3C(H)OO, the predominant paths directly produce cis-HC(O)OH and syn-CH3C(O)OH acids with >110 kcal/mol exothermicities via loose roaming-like insertion TSs involving the terminal O atom and the neighboring C-H bonds. For syn-CH3C(H)OO, the major decomposition channel occurs by abstraction of a H atom from the CH3 group by the terminal O atom producing CH2C(H)O-OH. At 298 K, the intramolecular insertion process in CH2OO was found to be 600 times faster than the commonly assumed ring-closing reaction.
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Trong-Nghia
authors.initials: TN
authors.lastname: Nguyen
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Raghunath
authors.initials: R
authors.lastname: Putikam
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: M C
authors.initials: MC
authors.lastname: Lin