Alcoholysis of dialkyl tetrazolylphosphonites

Abstract

Kinetics of the reaction of diisopropyl tetrazolylphosphonite with tert-butyl alcohol in dry THF have been studied in the presence of various acids, bases and salts that catalyze the process. Ammonium azolide salts were found to be considerably more efficient catalysts than the corresponding azole acids or tertiary amine bases. For instance, the relative rates obtained with N,N-diisopropylethylammonium tetrazolide, N,N-diisopropylethylamine and tetrazole were 104, 28 and 1, respectively. The salts of strong protolytes turned out to be better catalysts than those of weak ones. The susceptibility of the reaction rate to the pK_BH⁺ of the base is fairly strong (Brønsted β = 0.41) compared to the sensitivity to the pK_a of azoles (β = 0.17). The mechanisms of catalysis are discussed.