Theoretical Kinetic Study of Gas Phase Oxidation of Nicotine by Hydroxyl Radical
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JavierChavarrioThesis-1.pdf
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Javier Canas - Final Dissertation Paper
Embargo End Date:
2021-11-18
Type
ThesisAuthors
Chavarrio Cañas, Javier Eduardo
Advisors
Sarathy, Mani
Committee members
Mishra, Himanshu
Castaño, Pedro

Program
Chemical EngineeringKAUST Department
Physical Science and Engineering (PSE) DivisionDate
2020-11Embargo End Date
2021-11-18Permanent link to this record
http://hdl.handle.net/10754/666016
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At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis will become available to the public after the expiration of the embargo on 2021-11-18.Abstract
Cigarette smoke is suspected to cause diverse illnesses in smokers and people breathing second- and third-hand smoke. Although different studies have been done to elucidate the impact on health due to smoking, there is a lack of kinetic information regarding the degradation of nicotine under different environmental conditions. As a consequence, currently it is not possible to determine thoroughly the risk due to exposure to nicotine and the compounds derived from its decomposition. With the aim of contributing to clarify the different degradation paths followed by nicotine during and after the consumption of cigarettes, this work presents a theoretical study of the hydrogen atom abstraction reaction by hydroxyl radical at four sites in the nicotine molecule in a broad range of temperature, specifically be-tween 200-3000 K. The site-specific kinetic rate constants were computed by means of the multi-structural torsional variational transition state theory with small curvature tunneling contribution, performing ab initio calculations at the level M06-2X/aug-cc-pVQZ//M06-2X/cc-pVTZ. According to our computations, the dependence on temperature of the studied rate constants exhibited a non-Arrhenius fashion, with a minimum at 873 K. A negative temperature dependence was observed at temperatures lower than 873 K, indicating more prolonged exposure to nicotine in warmer environments. On the other hand, the opposite behavior was observed at higher temperatures; this non-Arrhenius be-havior results of interest in tobacco cigarette combustion, inducing different reaction mechanisms depending on the burning conditions of the different smoking devices. The results indicate that multi-structural and torsional anharmonicity is an im-portant factor in the computation of accurate rate constants, especially at high tem-peratures where the higher-energy conformers of the different species exert a larger influence. The anharmonicity factors suggest that disregarding the anharmonic de-viations leads to overestimation of the rate constant coefficients, by a factor between four and six. Our computed overall kinetic rate constant at 298 K exhibited very good agreement with the only experimental value meausred by Borduas et al. [1], af-fording certainty about our calculated site-specific rate constants, which are currently inaccessible to experiments. However, further experimental studies are necessary to validate our kinetic studies at other temperatures.Citation
Chavarrio Cañas, J. E. (2020). Theoretical Kinetic Study of Gas Phase Oxidation of Nicotine by Hydroxyl Radical. KAUST Research Repository. https://doi.org/10.25781/KAUST-60EK6ae974a485f413a2113503eed53cd6c53
10.25781/KAUST-60EK6