Deuterium kinetic isotope effect in β-elimination from (p-acetylphenethyl)dimethylsulphonium bromide. The influence of added dimethyl sulphoxide

The effect of added dimethyl sulphoxide (Me2SO) on the primary deuterium kinetic isotope effect for NaOH-catalysed β-elimination from (p-acetylphenethyl)dimethylsulphonium bromide has been measured over the range 6–70 mol %. Despite the large increase in reaction rate, no significant maximum in the isotope effect was observed. Substituent induced changes in k2H/k2D are shown to be larger than those caused by addition of Me2SO, despite the large difference in relative rates.