Kinetic Measurements of Cl Atom Reactions with C5–C8 Unsaturated Alcohols

Asma Grira,Cornelia Amarandei,Romeo Iulian Olariu,Manolis N. Romanias,Iustinian Gabriel Bejan,André Canosa,Patrice Coddeville,Gisèle El Dib,Alexandre Tomas,Cecilia Arsene

doi:10.3390/atmos11030256

Abstract

The reactions of five structurally similar unsaturated alcohols, i.e., (Z)-2-penten-1-ol, (E)-2-hexen-1-ol, (E)-3-hexen-1-ol, (Z)-3-hexen-1-ol, and 1-octen-3-ol, with Cl atoms in the gas phase, were investigated at 296 ± 2 K and 1 atm by the relative-rate kinetic technique using a 600-L Teflon reaction chamber. Selected ion flow tube mass spectrometry (SIFT-MS) was used simultaneously to monitor the decay of the alcohols of interest and selected reference compounds. Tetrahydrofuran (THF), propan-1-ol, and octane were used as reference compounds. Chlorine atoms were produced by the photolysis of molecular chlorine (Cl2) using broadband actinic lamps near 365 nm. The estimated rate constant values (in 10−10 cm3∙molecule−1∙s−1) followed the order 2.99 ± 0.53 ((Z)-2-penten-1-ol) < 3.05 ± 0.59 ((E)-3-hexen-1-ol) < 3.15 ± 0.58 ((Z)-3-hexen-1-ol) < 3.41 ± 0.65 ((E)-2-hexen-1-ol) < 4.03 ± 0.77 (1-octen-3-ol). The present work provides the first value of the rate constant for the reaction of 1-octen-3-ol with Cl atoms. The results are discussed and interpreted in relation to other studies where literature data are available. The structure–activity relationship and the atmospheric implications are discussed as well.

Highlights

Volatile organic compounds (VOCs) are trace gases generally present in the troposphere at sub-ppb concentrations
Five structurally similar unsaturated alcohols including (Z)-2-penten-1-ol, (E)-2-hexen-1-ol, (E)-3-hexen-1-ol, (Z)-3-hexen-1-ol, and 1-octen-3-ol were investigated with regard to their reactivity toward Cl atoms
The relative-rate kinetic approach was used to determine rate constant values of the target unsaturated alcohols reaction with Cl atoms produced by the photolysis of molecular chlorine

Summary

Introduction

Volatile organic compounds (VOCs) are trace gases generally present in the troposphere at sub-ppb concentrations. They play a major role in the chemistry of the troposphere through the formation of free radicals, ozone, and potentially secondary organic aerosols (SOA) [1,2]. Green leaf volatiles (GLV), such as unsaturated alcohols [5], are BVOCs which are emitted from vegetation either spontaneously or under stress conditions [6]. Their emissions may increase due to climate change [7]. The atmospheric reactivity of these compounds is less studied with respect to other BVOCs like monoterpenes

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Conclusion