A comparison of methods for pKa determination in strongly basic systems applied to the deprotonation of some heterocyclic methiodide salts

Abstract

Ionization values for the deprotonation of the methiodide salts 1–8, which occurs in strongly basic DMSO/water mixtures containing 0.047 M base, are used to determine pKa values by the Bunnett–Olsen and Marziano–Cimino–Passerini techniques, which involve extrapolation to the purely aqueous state. The resulting values are compared with those obtained using the H0q acidity function; agreement is good in most cases.