Ionizing properties of complexes with strong symmetrical hydrogen bonds in acid solutions in aprotic solvents

The acidity functions H₀ of solutions of trifluoroacetic acid (TFA) in DMF and methanesulfonic acid (MSA) in 2-pyrrolidone over an acid (HA) concentration range of 0–100% and of H₂SO₄ solutions in 2-pyrrolidone (66.7–100 mol % HA) at 25°C were determined using the indicator method. Data were obtained on the relative ionizing powers of the quasi-ion pairs S· · · H· · ·A (S is a solvent molecule) formed by DMF with acids (HCl, MSA, and TFA) and by MSA with DMF and 2-pyrrolidone. The effects of the acid anion (with MSA and H₂SO₄ solutions in 2-pyrrolidone acting as examples) and the counterion SH⁺ (with MSA solutions in DMF and 2-pyrrolidone acting as examples) on the ionizing power of (Ä · · ·H· · ·A)^– ions with strong symmetrical H-bonds were studied. It was found that, under comparable conditions, the replacement of a 2-pyrrolidone molecule by a DMF molecule in the SH⁺ cation insignificantly decreased the acidity of solution, whereas the (Ä· · ·H· · ·A)^– ions in H₂SO₄ solutions exhibited a much higher ionizing power than that of structurally similar anions in MSA solutions.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 44–49.Original Russian Text Copyright © 2005 by Kislina, Sysoeva, Librovich.