Abstract: As the first reported examples of carbon isotope effects in simple electrophilic addition reactions we have measured the carbon-14 kinetic isotope effects in the addition of 2, 4-dinitrobenzenesulfenyl chloride to a series of para-substituted a-and b-labeled styrenes in acetic acid at 30.1 OC: for para substituents C1, H, and CH3 the k/I4k values for a labeling are 1.027, 1.022, and 1.004, and the k/I4k values for b labeling are 1.035, 1.032, and ...