Weitere Evidenz für die mikroskopische Gleichzeitigkeit des Bruches zweier Bindungen bei einer E2‐Reaktion: H‐Isotopeneffekte und Substituentenwirkungen bei der Reaktion von 2,2‐Diphenyläthyl‐benzolsulfonat mit Methoxid‐Ion

Abstract Second order rate constants are determined for the E2 reactions of 2,2‐diphenyl‐ethyl benzenesulfonates Ph 2 C x HCH 2 O · O 2 S–C 6 H 4 –X with CH 3 ONa in methyl cellosolve solution ( x H = H or D, X = p ‐CH 3 O, p ‐CH 3 , H or p ‐NO 2 ). The H AMMETT ∂ values are of the same order of magnitude as those found in the first order solvolyses of methyl, ethyl or isopropyl benzenesulfonates. The primary deuterium isotope effects k H / k D are 5.27, 5.42 and 6.70 for X = p ‐CH 3 O, H and p ‐NO 2 . The ∂ values as well as the increase of k H / k D with introduction of p ‐NO 2 supply evidence for simultaneous C α O and C β H bond cleavages also in the E2 reactions of these compounds.