EFEITOS DAS MÚLTIPLAS ESTRUTURAS E DA ANARMONICIDADE TORCIONAL PARA AS REAÇÕES DE ABSTRAÇÃO DE HIDROGÊNIO NO BUTANOATO DE METILA PELO RADICAL H

IF 0.5 4区化学 Q4 CHEMISTRY, MULTIDISCIPLINARY

Quimica Nova Pub Date : 2023-08-28 DOI:10.21577/0100-4042.20230040

J. Nascimento, Tiago Alves

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引用次数: 0

Abstract

EFFECTS OF MULTIPLE STRUCTURES AND TORSIONAL ANHARMONICITY FOR THE HYDROGEN ABSTRACTION REACTIONS OF THE THMETHYL BUTANOATE BY H RADICAL. Thermal rate constants for the hydrogen abstraction reactions of the methyl butanoate (MB) by H radical were estimated by applying the multistructural canonical variational theory with small-curvature tunneling (CVT/SCT). The conformational search was performed at MPWB1K/6-31+G(d,p) level of theory and 68 distinguishable conformers for MB and transition state located. The multistructural and torsional anharmonicity effects were corrected through the rovibrational partition functions calculated with the multistructural method based on a coupled torsional potential, MS-T(C). The MS-CVT/SCT thermal rate constants are shown in good concordance with previous combustion models. After fitting the rate constants in a four-parameters equation, the activation energy showed a temperature dependence. The product branching ratios indicate a preference for (Rα) until 500 K. Above this temperature, the contribution of other reactions becomes relevant, especially for (Rβ).

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多结构和扭转非和谐对丁酸甲酯中氢自由基萃取反应的影响

多重结构和扭转不谐性对h自由基吸氢丁酸甲酯反应的影响。应用小曲率隧穿的多结构正则变分理论(CVT/SCT)估计了丁酸甲酯(MB)被H自由基抽氢反应的热速率常数。在MPWB1K/6-31+G(d,p)理论水平上进行构象搜索，找到68个可区分的MB和过渡态构象。通过基于耦合扭转势MS-T(C)的多结构方法计算的转振配分函数对多结构和扭转非调和效应进行了校正。MS-CVT/SCT热速率常数与以前的燃烧模型一致。在四参数方程中拟合速率常数后，活化能表现出温度依赖性。在500k之前，产物分支比表明偏爱(Rα)。在这个温度以上，其他反应的贡献是相关的，特别是(Rβ)。

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来源期刊

Quimica Nova 化学-化学综合

CiteScore

1.60

自引率

12.50%

发文量

审稿时长

2-4 weeks

期刊介绍： Química Nova publishes in portuguese, spanish and english, original research articles, revisions, technical notes and articles about education in chemistry. All the manuscripts submitted to QN are evaluated by, at least, two reviewers (from Brazil and abroad) of recognized expertise in the field of chemistry involved in the manuscript. The Editorial Council can be eventually asked to review manuscripts. Editors are responsible for the final edition of QN.