Kinetic isotope effects in reactions of isotopic exchange of the hydrogen of ferrocene with acid and base

Abstract

1. The kinetics of the hydrogen exchange of ferrocene, labeled with deuterium and tritium, was measured in acid and basic media. Exchange with liquid ammonia in the case of catalysis by potassium amide proceeds 30 times as rapidly in ferrocene as in benzene. 2. The kinetic isotope effect in the exchange of hydrogen in ferrocene with acid (KD/KT=1.2) is substantially lower than in the case of the exchange of hydrogen in aromatic compounds (KD/KT ≈ 2). 3. The kinetic isotope effect in the exchange of hydrogen in ferrocene with liquid ammonia, catalyzed by potassium amide, possesses a value close to that which was found for benzene and naphthalene, and shows that the protophilic mechanism of exchange in basic medium, established for other organic compounds, also holds in the case of ferrocene.