Rate coefficients for the reactions of OH radicals with C 3 –C 11 alkanes determined by the relative-rate technique
Year: 2024
Type: article
Abstract: . Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N2, Air, O2). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained KOH values (in units of 10-12 cm3·molecule-1·s-1) in different bath gases were N2, 7.90±0.25; Air, 7.93±0.33; and O2, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm3·molecule-1·s-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.
Authors: Yanyan Xin, Chengtang Liu, Xiaoxiu Lun, Shuyang Xie, Junfeng Liu, Yujing Mu
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,725
Awards: G3588064675, G3877991965, G622662732
OpenAlex ID: W4403318887