摘要
用HF/3-21G解析梯度方法研究H_2CCC:的氢氢键插入和加成反应机理,结果表明,H2CCC:的H—H插入为直接插入,取端端(end-on)接近方式;H_2加成经两步完成.第一步是2+2加成,因对称性禁阻取三中心过渡态,四中心作用发生在反应的后期,第二步是CH_3CHC:的1,2氢重排.预言气相中H—H插入容易发生,势垒值约为45 kJ/mol.
Reactions H2CCC: (1)+H2→CH2CCH2(2)+CH,CCH(3) are studied using HF/3-21Ggradient method. The insertion 1+H2→2 occurs easily in fashion of 'end-on' approach with a barrier of about 45 kJ/mol . The addition 1+H2→3 is fulfilled in two steps, the 2 + 2 addition toethenylenene carbene, then followed by 1,2-hydrogen migration. Because of the symmetry prohibition, the 2+2 addition proceeds via a 3-center transition state with a high barrier, the 4-center interaction occurs in the later stage. The reactions 1 + H2 are kinetically controlled with 2 as the major product. The requirements for the carbene addition are discussed.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1991年第5期644-647,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金
关键词
乙烯叉
碳烯
H-H插入
加成反应
H-H Insertion, 'End-on' approach, 2+2 addition, 3-Center transition state
