{"title":"Rate coefficients for the gas-phase reaction of OH radicals with the L4, L5, D5, and D6 permethylsiloxanes","authors":"François Bernard, James B. Burkholder","doi":"10.1002/kin.21769","DOIUrl":null,"url":null,"abstract":"<p>Rate coefficients, <i>k</i>(T), for the gas-phase OH radical reaction with decamethyltetrasiloxane ((CH<sub>3</sub>)<sub>3</sub>SiO[Si(CH<sub>3</sub>)<sub>2</sub>O]<sub>2</sub>Si(CH<sub>3</sub>)<sub>3</sub>, L<sub>4</sub>, <i>k</i><sub>1</sub>), dodecamethylpentasiloxane ((CH<sub>3</sub>)<sub>3</sub>SiO[Si(CH<sub>3</sub>)<sub>2</sub>O]<sub>3</sub>Si(CH<sub>3</sub>)<sub>3</sub>, L<sub>5</sub>, <i>k</i><sub>2</sub>), and decamethylcyclopentasiloxane ([–Si(CH<sub>3</sub>)<sub>2</sub>O–]<sub>5</sub>, D<sub>5</sub>, <i>k</i><sub>3</sub>), and dodecamethylcyclohexasiloxane ([–Si(CH<sub>3</sub>)<sub>2</sub>O–]<sub>6</sub>, D<sub>6</sub>, <i>k</i><sub>4</sub>) were measured using a pulsed laser photolysis—laser induced fluorescence absolute method over the temperature range 270–370 K. The obtained room temperature rate coefficients, with quoted 2σ absolute uncertainties, and fitted temperature dependence are (cm<sup>−3</sup> molecule<sup>−1</sup> s<sup>−1</sup>):\n\n </p><p>The 2σ absolute rate coefficient uncertainty, for all compounds included in this study, is conservatively estimated to be ∼10% over the entire temperature range. The cyclic permethylsiloxanes were found to be less reactive than the analogous linear compound, while both linear and cyclic compounds show increasing reactivity with increasing number of CH<sub>3</sub>- groups. A structure activity relationship (SAR) parameterization for the permethylsiloxanes is presented. The estimated atmospheric lifetimes due to OH reaction for L<sub>4</sub>, L<sub>5</sub>, D<sub>5</sub>, and D<sub>6</sub> are 5.2, 4.4, 6.8, and 5.2 days, respectively.</p>","PeriodicalId":13894,"journal":{"name":"International Journal of Chemical Kinetics","volume":"57 3","pages":"199-212"},"PeriodicalIF":1.5000,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/kin.21769","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Chemical Kinetics","FirstCategoryId":"92","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/kin.21769","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Rate coefficients, k(T), for the gas-phase OH radical reaction with decamethyltetrasiloxane ((CH3)3SiO[Si(CH3)2O]2Si(CH3)3, L4, k1), dodecamethylpentasiloxane ((CH3)3SiO[Si(CH3)2O]3Si(CH3)3, L5, k2), and decamethylcyclopentasiloxane ([–Si(CH3)2O–]5, D5, k3), and dodecamethylcyclohexasiloxane ([–Si(CH3)2O–]6, D6, k4) were measured using a pulsed laser photolysis—laser induced fluorescence absolute method over the temperature range 270–370 K. The obtained room temperature rate coefficients, with quoted 2σ absolute uncertainties, and fitted temperature dependence are (cm−3 molecule−1 s−1):
The 2σ absolute rate coefficient uncertainty, for all compounds included in this study, is conservatively estimated to be ∼10% over the entire temperature range. The cyclic permethylsiloxanes were found to be less reactive than the analogous linear compound, while both linear and cyclic compounds show increasing reactivity with increasing number of CH3- groups. A structure activity relationship (SAR) parameterization for the permethylsiloxanes is presented. The estimated atmospheric lifetimes due to OH reaction for L4, L5, D5, and D6 are 5.2, 4.4, 6.8, and 5.2 days, respectively.
期刊介绍：
As the leading archival journal devoted exclusively to chemical kinetics, the International Journal of Chemical Kinetics publishes original research in gas phase, condensed phase, and polymer reaction kinetics, as well as biochemical and surface kinetics. The Journal seeks to be the primary archive for careful experimental measurements of reaction kinetics, in both simple and complex systems. The Journal also presents new developments in applied theoretical kinetics and publishes large kinetic models, and the algorithms and estimates used in these models. These include methods for handling the large reaction networks important in biochemistry, catalysis, and free radical chemistry. In addition, the Journal explores such topics as the quantitative relationships between molecular structure and chemical reactivity, organic/inorganic chemistry and reaction mechanisms, and the reactive chemistry at interfaces.
京公网安备 11010802042870号
京ICP备2023020795号-1
分享
求助内容：
应助结果提醒方式：
扫码关注我们
