Thermodynamic and kinetic acidities in dimethyl sulphoxide. Part 2. Acetylenic compounds
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 4,p. 407-412
- https://doi.org/10.1039/p29770000407
Abstract
The pK values and proton transfer rates in anhydrous dimethyl sulphoxide are reported for three monosubstituted acetylenes (1)–(3) RCCH (R = Ph, MeOCH2, or Me2NCH2). The pK values were measured using a set of overlapping indicators: pK= 22.6, 23.5, and 24.2 for (1)–(3) respectively. Proton transfers were carried out by conjugate acetylide ions, arising from small additions of methylsulphinylmethanide (dimsyl) anion. Rate constants k1 followed the order of decreasing acidities: k1 2.92 × 106, 3.93 × 104, 2.92 × 103 l mol–1 s–1 at 25 °C for (1)–(3) respectively. The contribution from the dimsyl anion, though negligible, was also taken into account.Keywords
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