REACTIONS OF AZOLIUM CATIONS .2. REGIOSELECTIVE N2 ALKYLATION OF 5-ARYLTETRAZOLES WITH ISOPROPYL-ALCOHOL IN SULFURIC-ACID MEDIA - EFFECT OFELECTRONIC-PROPERTIES OF ARYL SUBSTITUENTS ON THE REACTION-RATE

Kinetics of regioselective N2 alkylation of a series of 5-(R-phenyl)te trazoles with isopropyl alcohol has been studied in 88.2, 94.3, and 98 .3% (w/w) sulfuric acid at 25 degrees. The true rate constants were ev aluated, logarithms of which were found to correlate with sigma degree s constants of phenyl substituents as log k = -0.488 sigma degrees - 0 .417. Small value of Hammett constant rho is evidence of a considerabl e isolation of the reaction center from the influence of the substitue nt at position C5 of the heteroring. This conclusion is confirmed by r esults of MNDO quantum chemical calculations of a series of 5-substitu ted 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. (C) 1995 John Wiley & Sons, Inc.