D. Souverain, A. Leborgne, G. Sauvet
1980
Citations
0
Influential Citations
14
Citations
Journal
European Polymer Journal
Abstract
Abstract Ionic trifluoromethanesulphonates (triflates) are strongly solvated with their conjugate acid in dichloromethane (Ph3C+, n-Bu4N+, Ag+) and acetonitrile (Na+, Ag+). A 1H and 19F NMR study of the chemical shifts of various acid-salt mixtures show that in CH2Cl2 three homoconjugates A− · HA, A−. (HA)2 and A−(HA)3 were formed with large formation constants whereas in acctonitrile only the 1:1 homoconjugate was formed with an equilibrium constant K1 ∼ 4 1 · M−1. This result explains why the protonation by CF3SO3H of non-polymerizable olefins such as 1,1-diphenylethylene and 3-phenylindene is always incomplete ( 1 3 and 1 2 respectively) in CH2Cl2. Conditions in which covalent triflates could be obtained have been investigated. As a consequence of homoconjugation, reaction of Ph3COH with triflic anhydride led to Ph3C+ CF3SO−3 HOSO2CF3. Other tertiary alcohols were dehydrated by triflic anhydride and led to ethylenic compounds (1,1-diphenylethanol) or ethers (2-phenyl 2-propanol). Esters were only observed in the case of benzyltriflate (at −20°) and in the case of 1-phenylethyltriflate which is a model of polystyryltriflate (stable at room temperature).