Equilibrium protonation of the 1,3,5-trinitrobenzene–phenoxide σ-complex
The protonation behavior of the trinitrobenzene–phenoxide σ-complex has been determined in aqueous sulfuric acid, aqueous hydrochloric acid, and ethanolic hydrogen chloride. The conjugate acid of the σ-complex, a nitronic acid, exhibits acidic properties similar to those of picric acid and the cyanocarbon acids. The acidity (pKa) of the nitronic acid has been evaluated with the aid of various acidity function techniques and using the Bunnett–Olsen method. The nitronic acid is ca. 1 pK unit stronger than picric acid. However, both the nitronic acid and picric acid are considerably weaker acids in ethanolic than in aqueous media (ΔpK ca. 4 units). The results provide a preliminary H− acidity function scale for aqueous and ethanolic hydrogen chloride.
Erratum to “Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study”