Thomas E. Dueber

Vinyl cations. Part 13. Secondary kinetic deuterium isotope effects in the solvolysis of ring-substituted β-styryl trifluoromethanesulphonates

The β-kinetic deuterium isotope effects have been measured in the solvolysis of a series of ring-substituted β-styryl trifluoromethanesulphonates. At 75 °C in aqueous 80% ethanol for the parent compound, kH/kD= 1.45; for p-Cl, kH/kD= 1.74; for m-Cl, kH/kD= 1.61; for p-CF3, kH/kD= 1.64; for p-NO2, kH/kD= 1.71. Both the protio- and deuterio-series gave an excellent Hammett correlation with σ+(ρ–4.12 and –4.17, respectively). The products of solvolysis were the corresponding acetophenones and phenylacetylenes. The significance of these results is discussed.

Deuterium isotope effects in the solvolytic reactivity of simple alkylvinyl trifluoromethanesulphonates

The kinetic as well as product deuterium isotope effects have been measured in the solvolysis of 1-trideuteriomethyl-2-methylprop-1-enyl (2b), cis-(3b), and trans-2-deuterio-1-methylprop-1-enyl (4b) trifluoromethanesulphonates as well as the 3,3,3-trideuterio-1-methyl-2-trideuteriomethylprop-1-enyl ester (2c). At 75° in aqueous 60% ethanol for (2b)kH/kD= 1·54, for (3b) 1·25, for (4b) 2·01, and for (2c) 0·96. The significance of these results are discussed.

Secondary kinetic deuterium isotope effects in vinyl cations

The β-deuterium isotope effect in the solvolysis of β-styryl trifluoromethanesulphonate (1), kH/kD= 1·42, is much larger than in normal carbonium ions.