The rate constants of quenching of the triplet state T₁ of four aromatic ketones by triethylamine in acetonitrile show no correlation with the Gibbs energy of the reaction, but depend on the nature of T₁, i.e. n–π*, π–π* or charge transfer (CT) type. For example, the ratio of rate constants between two systems of n–π* and CT type, with the same driving force, is over 10⁸. It is concluded that these reactions are kinetically controlled, the decisive factor for the activation energy being the electrostatic charge distribution of the carbonyl group in the triplet state.