82639-02-9Relevant academic research and scientific papers
Addition of Trifluoroacetic Acid to Substituted Styrenes
Allen, Annette D.,Rosenbaum, Murray,Seto, Nina O. L.,Tidwell, Thomas T.
, p. 4234 - 4239 (2007/10/02)
The rate of addition of CF3CO2H to a series of ring-substituted styrenes ArCH=CH2 with 100percent, 50percent, and 20percent solutions of the acid in CCl4 have been measured.The rate of addition of 100percent CF3CO2H to the isomeric 1-phenylpropenes and the rate of cis- to trans-stilbene isomerization by this acid are also reported.The rates are correlated with ?+ parameters of the substituents and with aqueous H2SO4-catalyzed hydrations of the same substrates.Deviations from the ?+ correlation occur with substituents capable of strong hydrogen bonding to the acidic solvents; these deviations are attributed to a decrease in substituent electron-donating ability caused by this interaction.All of the evidence supports a mechanism of rate-determining protonation on carbon (the AdE2 mechanism), with no detectable effects from ? complexation of the acids with the substrates.
A KINETIC STUDY OF THE MECHANISM OF ESTERIFICATION OF 1-ARYLETHANOLS IN TRIFLUOROACETIC ACID
Gillen, Ciaran J.,Knipe, Anthony C.,Watts, William E.
, p. 597 - 600 (2007/10/02)
Aryl substituent effects upon the rate constants for the esterification of a series of 1-arylethanols in trifluoroacetic acid are in accordance with a reverse AAL1 mechanism, for wich the Hammett reaction constant ρ=-3.69 has been determined by correlation with ?+ substituent constants.The rates of reaction are ca. 50-fold faster than those for corresponding benzyl alcohols which bear an electron-donating aryl substituent and which are also believed to undergo esterification in trifluoroacetic acid by the reverse AAL1 mechanism; the reverse AAC2 mechanism applies to benzyl alcohols which bear an electron-withdrawing aryl substituent.
