Halide assisted addition of hydrogen halides to alkenes

Autor:	Hilton M. Weiss, Kim M. Touchette
Rok vydání:	1998
Předmět:	chemistry.chemical_classification chemistry.chemical_compound chemistry Alkene Trifluoroacetic acid Halide Protonation Carbocation Methylene Photochemistry Alkyl Ion
Zdroj:	Journal of the Chemical Society, Perkin Transactions 2. :1517-1522
ISSN:	1364-5471 0300-9580
DOI:	10.1039/a703570e
Popis:	The addition of 0.1 M quaternary ammonium halide to a solution of 20% trifluoroacetic acid in methylene chloride causes a large rate increase in the reaction of simple alkenes leading to a mixture of alkyl halides and trifluoroacetates. The mechanism is proposed to involve a halide assisted protonation of the alkene which produces a carbocation intermediate sandwiched between the attacking halide ion and the trifluoroacetate ion. At higher concentrations of halide ion, the proton donating ability of the solution decreases, slowing the reaction and increasing the efficiency of cation capture by the halide ion. This leads to a greater proportion of unrearranged halide product. At the highest concentration of halide ion, cation rearrangement is virtually eliminated.
Databáze:	OpenAIRE
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