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自由基环合反应中链结构的影响

发表时间:2016-07-15  浏览量:4465  下载量:2497
全部作者: 蒋原野,徐正阳,傅尧
作者单位: 中国科学技术大学化学与材料科学学院
摘 要: 自由基环合反应是一种构建环状化合物的有效方法。这里利用密度泛函理论(density functional theory,DFT)方法对1-己烯和1-戊烯及其衍生物的自由基环合反应中链结构的影响进行考察。计算结果显示,链上偕二甲基取代会普遍促进自由基环合和增大反应能。NH、O和S替代碳自由基邻位亚甲基会普遍升高环合能垒,它们替代双键邻位亚甲基时会降低5-endo环合能垒,而替代与碳自由基和烯基都不相邻的亚甲基时会普遍降低环合能垒。此外,endo环合反应的能垒与反应能具有良好的线性关系,而exo环合不具备这种规律。
关 键 词: 有机化学;自由基;环合;区域选择性
Title: Free radical cyclization: effects of chain structures
Author: JIANG Yuanye, XU Zhengyang, FU Yao
Organization: School of Chemistry and Materials Science, University of Science and Technology of China
Abstract: Radical cyclizations are efficient methods for the construction of cyclic compounds. Herein density functional theory (DFT) methods were used to investigate the effects of chain structure on the radical cyclization of 1-hexene, 1-pentene and their derivatives. Calculation results reveal that substitution on the alkyl chain by gem dimethyl groups generally promotes cyclization and increases reaction energies. Replacing the methylene group adjacent to carbon radical by NH, O and S increases the energy barriers of cyclization while the same replacements on the methylene group adjacent to the double bond decreases the energy barriers of 5-endo cyclization. Meanwhile, changing the methylene group not adjacent to neither the carbon radical nor the double bond to NH, O and S facilitates the cyclization in general. Furthermore, it is found that there is a good linear relationship between the energy barriers and reaction energies in endo cyclization whereas no such linear relationship found in exo cyclization.
Key words: organic chemistry; free radical; cyclization; regioselectivity
发表期数: 2016年7月第13期
引用格式: 蒋原野,徐正阳,傅尧. 自由基环合反应中链结构的影响[J]. 中国科技论文在线精品论文,2016,9(13):1314-1321.
 
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