Addition-Insertion-Elimination Reactions of O(3P) With Halogenated Iodoalkanes Producing HF(v) and HCI(v)

Published

February 1, 2001

Author(s)

T P. Marcy, J P. Reid, C X. Qian, S R. Leone

Abstract

The reaction of CH₂ICF₃ and other fluorinated or chlorinated iodoalkanes with O(³ P), generated by microwave discharge of O₂ or 193 nm photolysis of SO₂, produces vibrationally excited HF(Ņ) or HCI(Ņ), as observed by steady state or time-resolved Fourier transform infrared (FTIR) emission spectroscopy. This process occurs even in competition with possible pathways to form HOI or IO products. The proposed mechanism is an addition-insertion-elimination process. The nascent vibrational distribution of the HF(nu} produced from O+CH₂ICF₃ is determined to be 0.58 0.10, 0.29 0.08, and 0.12 0.03 for Ņ = 1, 2, and 3, respectively, with an upper bound of 0.04 from a few observed lines of Ņ=4. The monotonically decreasing vibrational distribution suggests a reaction involving HF(nu} elimination from an intermediate complex. There are a number of possible single or multistep kinetic pathways that could produce HF(nu} under these conditions. To determine the predominant pathway that produces the observed HFŅ, the dependence of the time-resolved HFŅ emission signal on reactant concentrations is measured and compared with kinetics simulations. The results suggest a single step mechanism involving initial OO³P) attack on the iodine of the CH₂ICF₃, in a manner similar to the start of the reaction of O(³P) with C₂H₅I that produces HOI. This is followed by insertion of the oxygen atom into the carbon-iodine bond of the CH₂ICF₃, producing an activated complex with sufficient energy to eliminate HFŅ.

Citation

Journal of Chemical Physics

Volume

114

Issue

No.5

Pub Type

Journals

Keywords

addition, elimination, HCI, HF, insertion

Citation

Marcy, T. , Reid, J. , Qian, C. and Leone, S. (2001), Addition-Insertion-Elimination Reactions of O(³P) With Halogenated Iodoalkanes Producing HF(v) and HCI(v), Journal of Chemical Physics (Accessed November 8, 2024)