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

摘要

The acidity functions H-0 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 degrees C were determined using the indicator method. Data were obtained on the relative ionizing powers of the quasi-ion pairs S center dot center dot center dot H center dot center dot center dot 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 (A center dot center dot center dot H center dot center dot center dot 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 (A center dot center dot center dot H center dot center dot center dot A)(-) ions in H2SO4 solutions exhibited a much higher ionizing power than that of structurally similar anions in MSA solutions.