首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Mechanism of the cyclopropenone decarbonylation reaction. A density functional theory and transient spectroscopy study
Authors:Poloukhtine Andrei  Popik Vladimir V
Institution:Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
Abstract:The density functional theory analysis predicts that the thermal decarbonylation of cyclopropenones proceeds by the sequential and regioselective cleavage of both single bonds in a three-membered ring. The initial ring-opening process results in the formation of a reactive zwitterionic intermediate 6, which is separated from the free alkyne and carbon monoxide by a very low energy barrier. Femtosecond pump-probe transient absorption spectroscopy experiments showed that light-induced decarbonylation is also a stepwise process but apparently proceeds on the excited-state surface. The lifetime of the intermediate in the photodecarbonylation reaction is very short and is dependent on substitution and solvent polarity. Thus, bis-p-anisyl-substituted species decays with tau = 0.6 ps, bis-alpha-naphthyl-substituted intermediate has a lifetime of tau = 11 ps, while the bis(2-methoxy-1-naphthyl)-substituted analogue survives for 83 ps in chloroform and for 168 ps in argon-saturated methanol. The loss of carbon monoxide from these intermediates results in the formation of corresponding acetylenes in an electronically ground state. The addition of triplet quenchers does not affect the dynamics or outcome of the reaction.
Keywords:
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号