Journal of Organic Chemistry p. 2818 - 2825 (1985)
Update date:2022-08-04
Topics:
Kumar, C. V.
Ramaiah, D.
Das, P. K.
George, M. V.
Upon 337.1-nm laser excitation, chalcone epoxides containing donor/acceptor substituents at para positions of phenyl and benzoyl groups undergo triplet-mediated ring opening to carbonyl ylides observable by broad absorption spectra (λmaxY=520-600 nm, εmaxY (13-27) x 103 M-1 cm-1 in benzene) on a microsecond time scale (τY=0.4-24 μs in benzene).The short-lived, carbonyl-type triplets (τT=0.8-100 ns) giving rise to ylides are monitored in some cases by direct transient absorption on a nanosecond time scale and, for all systems, are probed by quenching studies with 1-methylnaphthalene and 2,5-dimethyl-2,4-hexadiene.Substituent effects on ylide absorption maxima, ylide decay kinetics, reactivity toward dipolarophiles and methanol, and precursor triplet lifetimes are discussed in the light of charge delocalization in dipolar structures, variation in HOMO/LUMO energies, complexity of thermal processes contributing to ylide decay, and energy gap between an ylide triplet and its triplet carbonyl precursor (ring closed).
View MoreContact:86-10-62983737; +86-10-51287608
Address:4/F Building C, 2 Shangdi Xinxi Road
SICHUAN ZHONGBANG NEW MATERIAL CO., LTD
website:http://www.zhongbangst.com
Contact:86-830-2585019
Address:sichuan,china
Tianjin Tensing Fine Chemical Research Develop Centre
Contact:86-022-23718576,13032267585
Address:2-2-201,13 Guiyuan road,Huayuan Industry district,Tianjin,china
Shijiazhuang Yunxuan Im&Export Co.,Ltd.
Contact:+86-311-83037514
Address:No.6 Hongbin Road
Suzhou Howsine Biological Technology Co.,Ltd(expird)
website:http://www.howsine.com
Contact:86-512-67262751
Address:No 3,Weihua Road ,Suzhou Industrial Park ,Jiangsu ,China.
Doi:10.1139/v64-040
(1964)Doi:10.1021/jo00220a030
(1985)Doi:10.1021/jacs.0c11119
(2021)Doi:10.1002/ejoc.200600009
(2006)Doi:10.1246/bcsj.58.731
(1985)Doi:10.1016/S0040-4039(00)61948-2
(1985)