Title

The competition of the loss of a beta fluoride and hydron transfer between carbon and oxygen during exchange and elimination reactions

Document Type

Article

Publication Date

1-1-2008

Abstract

Reactions of methanolic sodium methoxide with the series p-CF C H C HClR [R is -CH Cl, -CH F, -CHClF, -CHF , -CF Cl or -CF ] are reported to probe reaction mechanisms for dehydrohalogenation reactions compared to hydron exchange. All of the dehydrochlorinations and dehydrofluorinations from CH F occur by a two step mechanism via a hydrogen-bonded carbanion intermediate. Dehydrofluorinations from CHF occurs via a carbanion no longer stabilized by a hydrogen bond and the fluoride ion is eliminated faster than proton transfer from methanol. Reactions from the CF occur from a similar intermediate but exchange of the benzylic proton is faster than the dehydrofluorination. Reactions of ethanolic sodium ethoxide are also reported with the series P-CF C H C HFR [R is -CH F, -CHF , -CF Cl or -CF ]. Density functional calculations using B3LYP/6-31+G(d,p) were used to probe the compounds and intermediates. © by Oldenbourg Wissenschaftsverlag. 3 6 4 X X 2 2 2 2 3 2 2 3 3 6 4 X X 2 2 2 3 i i

Publication Name

Zeitschrift fur Physikalische Chemie

Volume Number

222

First Page

1175

Last Page

1184

Issue Number

8-9

DOI

10.1524/zpch.2008.5381

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