The Competition of the Loss of a Beta Fluoride and Hydron Transfer Between Carbon and Oxygen During Exchange and Elimination Reactions

Autor:	Pasquale Iacono, Judith G. Koch, Nicole M. Wedgwood, Heinz F. Koch, Masaaki Mishima
Rok vydání:	2008
Předmět:	Hydron media_common.quotation_subject Inorganic chemistry Kinetics chemistry.chemical_element Oxygen Competition (biology) chemistry.chemical_compound Elimination reaction chemistry Physical and Theoretical Chemistry Fluoride Carbon media_common
Zdroj:	Zeitschrift für Physikalische Chemie. 222:1175-1184
ISSN:	2196-7156 0942-9352
DOI:	10.1524/zpch.2008.5381
Popis:	Reactions of methanolic sodium methoxide with the series p-CF3C6H4C i HClRX [RX is -CH2Cl, -CH2F, -CHClF, -CHF2, -CF2Cl or -CF3] are reported to probe reaction mechanisms for dehydrohalogenation reactions compared to hydron exchange. All of the dehydrochlorinations and dehydrofluorinations from CH2F occur by a two step mechanism via a hydrogen-bonded carbanion intermediate. Dehydrofluorinations from CHF2 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 CF3 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-CF3C6H4C i HFRX [RX is -CH2F, -CHF2, -CF2Cl or -CF3]. Density functional calculations using B3LYP/6-31+G(d,p) were used to probe the compounds and intermediates.
Databáze:	OpenAIRE
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