The influence of sodium trifluoroacetate on the acidity function of solutions of trifluoroacetic acid in N,N-dimethylformamide

The influence of CF₃COONa on the acidity function (H ₀) and IR spectra of the CF₃COOH-N,N-dimethylformamide (DMF)-CF₃COONa system (CF₃COOH] ≤ DMF], CF₃COONa] = 0–3 M) and H ₀ of solutions of the salt in 100% CF₃COOH (CF₃COONa] = 0–1.2 M) was studied. The addition of the salt to 100% CF₃COOH insignificantly changed solution acidity; H ₀ passed a minimum at CF₃COONa] = 0.7 M because of the formation of (CF₃COO…H…OOCCF₃)^? anions and destruction of acid associates in the presence of the salt. Changes in the acidity of solutions of CF₃COOH in DMF caused by the addition of the salt depended on the n = CF₃COOH]/DMF] ratio. At n = 1, the salt almost did not influence H ₀. At n < 1, a substantial decrease in the acidity of solutions was observed, because the salt increased the degree of proton transfer in CF₃COO…H…OC(H)N(CH₃)₂ quasi-ion pairs solvated by DMF molecules.