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

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, CH₂OO + 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

KEYWORDS:

• Carbonyl oxides
• Criegee intermediates
• tropospheric chemistry
• photoionisation
• kinetic isotope effect

Acknowledgements

This material is based upon work supported by the Office of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, United States Department of Energy (USDOE). This research was carried out in part by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA), supported by the Upper Atmosphere Research and Tropospheric Chemistry program. The contributions of RLC and KZ were in part supported by appointments to the NASA Postdoctoral Program at the NASA Jet Propulsion Laboratory, administered by Universities Space Research Association under contract with NASA. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the USDOE’s National Nuclear Security Administration under contract DE-NA0003525. Argonne National Laboratory is supported by the USDOE, Office of Science, BES, Division of Chemical Sciences, Geosciences, and Biosciences under Contract No. DE-AC02-06CH11357. The Advanced Light Source is supported by the Director, Office of Science, USDOE BES under Contract DE- AC02-05CH11231 at Lawrence Berkeley National Laboratory. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the USDOE or the United States Government.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Basic Energy Sciences: [Grant Number Chemical Sciences, Geosciences, and Biosciences,DE-AC02-05CH11231,DE-AC02-06CH11357]; National Aeronautics and Space Administration: [Grant Number NASA postdoctoral program, Upper Atmosphere Research & Tropospheric Chemistry]; National Nuclear Security Administration: [Grant Number DE-NA0003525].