Journal of the American Chemical Society p. 5657 - 5664 (1981)
Update date:2022-08-02
Topics:
Fraenkel, Gideon
Hallden-Abberton, Michael P.
Peralkylcyclohexadienyllithium compounds (2a,b), formed by addition of alkyllithiums to triene 1, are shown to exist as ion-paired aggregates containing conjugated anions bent out of the plane at the saturated ring carbon.Both 13C and 7Li NMR spectra show 2a,b to form two distinctly different ion-paired species - tight peripherally solvated ion-pair aggregates in the presence of mainly tertiary amines and loose separated ion-pair dimers favored with THF, glymes, and HMTP.The latter exhibit two 7Li(+) peaks, one due to Li sandwiched between two anions in a triple ion and the other situated external to it.In the case of 2b with THF both ion-pair species are dimers, and the equlibrium (A(-)Li(+))2*(THF)2 + THF <--> (A2Li)(-) + Li(THF)3(+) is characterized with ΔH = -4 kcal and ΔS = -16 eu.The exchange of ions between ion pairs of 2b with THF is generally slow on the NMR time scale.However, above 0 deg C the lithium exchange rate between the solvated site in the loose ion-pair dimer and the lithium in the tighter ion-pair dimer lies on the NMR time scale.The mean lifetime of lithium in the triple ion is always > 10 s.The slow ion-exchange rates are ascribed to the crowded substitution around 2a,b.
View MoreHangzhou innopharma technology Co,.Ltd.(expird)
Contact:+86-13388601988
Address:Room845,lixin building, moganshan road, hangzhou, china
SuZhou Hua-Emy Chemical Import and Export Co., LTD.
Contact:+86-512-88804994; +86-512-88804550;
Address:710, Building B, International Trade Center, 12 Huanghelu, Changshu, Jiangsu,China
WEIFANG RICHEM INTERNATIONAL LTD
Contact:86-536-2222176
Address:weifang,shandong
ChangZhou XiaQing Chemical Co., Ltd.
Contact:+86-519-88721665
Address:3# Hengluo Road, Henglin Town, Changzhou City, Jiangsu Province,China
Contact:(86) 731 88718666
Address:Room 1222, Unit 4, Building B, Shangcheng, No.47, Kaiyuan East Road.
Doi:10.1016/j.tet.2018.07.055
(2018)Doi:10.1139/v81-432
(1981)Doi:10.1016/j.bmc.2015.12.019
(2016)Doi:10.1016/j.bmc.2004.07.029
(2004)Doi:10.1039/P19810002656
(1981)Doi:10.1055/s-1986-31804
(1986)