Applicability of the HT acidity function to the protonation of thioamides, thioureas, and thionesters

Abstract

The protonation of eleven thioamides, five thioureas, and four thionbenzoates in aqueous sulfuric acid has been found to follow the HT acidity function with acceptable accuracy. Protonation constants pKTH+ obtained by use of HT agreed fairly well with pKTH+ values obtained by the Bunnett–Olsen method, but less well with those obtained by the Marziano–Cimino–Passerini procedure. Linear free-energy relationships of pKTH+ values are discussed.