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Kinetics and mechanism of the alcoholyses of ethyl fluorosulphate
Author(s) -
Cafferata Lázaro F. R.,
Svartman Esther L.
Publication year - 1991
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610040408
Subject(s) - chemistry , isopropyl , reactivity (psychology) , kinetics , alcohol , reaction rate constant , benzene , halide , trifluoromethanesulfonate , acetone , medicinal chemistry , alkyl , hydrolysis , transition state , organic chemistry , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
The alcoholyses of ethyl fluorosulphate in methyl, ethyl, n ‐propyl, isopropyl, n ‐butyl, isobutyl, tert ‐butyl and n ‐pentyl alcohols in the initial concentrations and temperature ranges of (1–10) 10 −3 M and − 15.00 to 22.00 °C, respectively, were studied. The reactions follow pseudo‐first‐order kinetic laws up to at least ca 75 per cent ester conversions. At 10°C the experimental rate constant for ethanolysis is similar to that of ethyl triflate but much smaller than for its hydrolysis. The reactivity of the ester is ca 10 4 –10 5 times higher than that of alkyl halides and benzenesulphonates. In alcohol–benzene and alcohol–acetone mixtures the Δ H ≠ and Δ S ≠ activation parameters are only slightly affected by the media composition. The effect of the ‘lyate ion’ on the kinetics of these reactions were investigated and the effects of changes in the dielectric constant of the media were evaluated. It is concluded that the alcoholyses of the ester fulfil the requirements for predominant S N 2‐ type mechanism, where the reaction ground states are more polar than the corresponding transition states .