Quantitative calculation method to compare the reactive sites of different methyl esters

Autor: Hua Wang, Yong-hui Wu, Fashe Li, Quan Xiao, Bao-ping Ding, Zi-hao Ni
Rok vydání: 2022
Předmět:
Zdroj: Fuel. 307:121228
ISSN: 0016-2361
DOI: 10.1016/j.fuel.2021.121228
Popis: Methyl ester is the main component of biodiesel, which plays a crucial role in constructing chemical kinetic models for the combustion. The carbon chain length and the degree of unsaturation have a significant influence on the molecular properties and reactivity of methyl esters. In this study, to explore the difference in chain length and reactive sites of methyl esters, the quantum chemical approach is used to examine the chemical reaction sites of methyl butyrate, methyl crotonate, methyl heptanoate, and methyl enanthate. Based on density functional theory, the structure of the four methyl ester molecules is optimized under the M06-2X method, and the global reactivity (including molecular electrostatic surface potential, frontier molecular orbital) and local reactivity (including Fukui function, charge, and natural bond orbital) are analyzed. At the same time, the visualization results are also obtained. The results show that the reactive sites of saturated methyl ester occur in the structure of the ester group, and the reactive sites of methyl crotonate occur on the ester group and the double bond. Further, the reactivity of methyl crotonate is stronger than that of the three saturated methyl esters. As the carbon chain grows, the reactivity of saturated methyl esters gradually increases. Overall, the results provide a theoretical basis for revealing the different structural properties of methyl esters and subsequent chemical kinetic calculations.
Databáze: OpenAIRE
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