Insertion products in the reaction of carbonyl oxide Criegee intermediates with acids: Chloro(hydroperoxy)methane formation from reaction of CH2OO with HCl and DCl. (17th September 2021)

• Record Type: Journal Article
• Authors: Taatjes, Craig A.; Caravan, Rebecca L.; Winiberg, Frank A. F.; Zuraski, Kristen; Au, Kendrew; Sheps, Leonid; Osborn, David L.; Vereecken, Luc; Percival, Carl J.
• Is Part Of: Molecular physics. Volume 119:Number 17/18(2021)
• Publication Date: 2021-09-17
• Subjects: Carbonyl oxides -- Criegee intermediates -- tropospheric chemistry -- photoionisation -- kinetic isotope effect; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2021.1975199
• Languages: English
• ISSNs: 0026-8976

Abstract

Abstract : The reactions of carbonyl oxide Criegee intermediates with acids proceed predominantly by an insertion mechanism. We characterise the products from one of the simplest reactions of carbonyl oxides with inorganic acids, CH2 OO + hydrogen chloride, which occurs via a 1, 2-insertion in the H–Cl bond. Reactions of both HCl and DCl isotopologues yield product signal at the mass of the insertion product chloro(hydroperoxy)methane and a dissociative ionisation peak at the mass of the protonated (or deuteronated) Criegee intermediate. The isotopic composition of the insertion product has been measured for reaction mixtures where both HCl isotopologues are present, and the H/D ratio of the product is consistently higher (by a factor of 1.6 ± 0.3) than that of the reactants. This isotope selectivity in the products has smaller uncertainty than the ratio of measured rate coefficients and suggests a normal ( k H > k D ) kinetic isotope effect in the reaction. Theoretical kinetics calculations predict a small normal kinetic isotope effect for the overall reaction ( k H / k D = 1.35 at 20 Torr N2 and k H / k D = 1.2 at 1 atm N2 ) but predict a substantial inverse kinetic isotope effect ( k D > k H ) for the stabilisation fraction, in disagreement with the experimental observation. GRAPHICAL ABSTRACT: UF0001