pH of N,N-Dimethylformamide in [Bmim][BF<sub>4</sub>] and [Bmim][PF<sub>6</sub>] Ionic Liquids

The pH value of binary mixtures containing N,N-dimethylformamide (DMF) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) ionic liquids over the range of N,N-dimethylformamide mole fraction from (0.1 to 0.9) and temperature range from (293.15 to 338.15) K were measured. The range of pH values of N,N-dimethylformamide and [Bmim][BF4] and [Bmim][PF6] were from (3.42 to 6.50) and (6.98 to 9.74), respectively. Comparison showed that the pH of N,N-dimethylformamide in the two ionic liquids was in sequence: [Bmim][BF4] < [Bmim][PF6] at the same conditions. The temperature dependency of the pH value was correlated using an empirical equation. The correlations gave satisfactory results.