Reactions of Azolium cations. II [1]. Regioselective N2 alkylation of 5‐aryltetrazoles with isopropyl alcohol in sulfuric acid media: Effect of electronic properties of aryl substituents on the reaction rate

Kinetics of regioselective N2 alkylation of a series of 5‐(R‐phenyl)tetrazoles with isopropyl alcohol has been studied in 88.2, 94.3, and 98.3% (w/w) sulfuric acid at 25°. The true rate constants were evaluated, logarithms of which were found to correlate with σ° constants of phenyl substituents as log k = −0.488 σ° − 0.417. Small value of Hammett constant ρ is evidence of a considerable isolation of the reaction center from the influence of the substituent at position C5 of the heteroring. This conclusion is confirmed by results of MNDO quantum chemical calculations of a series of 5‐substituted tetrazolium cations. A correlation between logarithms of the true rate constants and the calculated net effective charges on atoms N2(N3) for 5‐(R‐phenyl)tetrazolium cations has been revealed. © 1995 John Wiley & Sons, Inc.