Reaction Pathways for the Thermal Decomposition of Methyl Butanoate

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• 作者：Mohamad Akbar Ali ; Angela Violi
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：June 21, 2013
• 年：2013
• 卷：78
• 期：12
• 页码：5898-5908
• 全文大小：741K
• 年卷期：v.78,no.12(June 21, 2013)
• ISSN：1520-6904

文摘

In recent years, biodiesel fuels, consisting of long-chain alkyl (methyl, ethyl, propyl) esters, have emerged as viable alternatives to petroleum-based fuels. From a combustion chemistry standpoint, there is great interest in developing accurate reaction models for these new molecules that can be used to predict their behaviors in various regimes. In this paper, we report a detailed study of the unimolecular decomposition pathways of methyl butanoate (MB), a short-chain ester that contains the basic chemical structure of biodiesel fuels. Using ab initio/DFT methods, we identified five homolytic fissions of C鈥揅 and C鈥揙 bonds and five hydrogen transfer reactions. Rate constants were determined using the G3B3 theory coupled with both variational transition state theory and Rice鈥揜amsperger鈥揔assel鈥揗arcus/master equation simulations with hindered rotation corrections. Branching ratios in the temperature range 1500鈥?200 K indicate that the main pathway for thermal decomposition of MB is the reaction CH₃CH₂CH₂C(鈺怬)OCH₃ 鈫?C₂H₅ + CH₂C(鈺怬)OCH₃. The results, in terms of reaction pathways and rate constants, can be used for future development of mechanisms for long alkyl-chain esters.