Nucleophilicity Parameters for Nitroalkyl Anions in Methanol and Structure-Reactivity Analysis

A kinetic study is reported for the addition of nitroalkyl anions 2 a-c at the C-7 position of the 4-nitrobenzochalcogenadiazoles 1 a-c in methanol at 20 degrees C. By using the Mayr approach, the nucleophilicity parameters N and the nucleophile specific parameters s(N) of these nitroalkyl anions 2 a-c have been determined and discussed. The structure-reactivity relationships are discussed, and it is shown that the measured nucleophilicity parameters (N) of anions 2 a-c are linearly related (r(2)=0.9934) to their acidity constant (pK(aH)(MeOH)) in methanol. In addition, satisfactory linear correlation has been evidenced between the experimental nucleophilicity N parameter and the theoretical model of nucleophilicity omega(-1) for the various nitroalkyl anions 2 a-c in methanol.