Volumetric and Acoustic Properties of a DBU (1,8-Diazobicyclo[5.4.0]undec-7-ene) Based Protic Ionic Liquid in Water at T = (293.15 to 328.15) K

The protic ionic liquid, 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium trifluroacetate [DBUTFA], has been synthesized and densities of and speeds of sound in (DBUTFA + water) binary mixtures were measured simultaneously using a vibrating-tube digital density and speed of sound analyzer (Anton Paar, DSA 5000 M) at T (293.15 to 328.15) K, with 5 K interval, and at atmospheric pressure. From the experimental density and speed of sound data, apparent molar volumes, $$ V-{\phi } $$ V ?, and apparent molar isentropic compressibilities, $$ K-{S,\phi } $$ K S, ?, were determined and further analyzed using Redlich-Mayer type equations to evaluate the corresponding infinite dilution apparent molar volumes, $$ V-{2}^{\infty } $$ V 2 ?, infinite dilution apparent molar isentropic compressibilities, $$ K-{S,2}^{\infty } $$ K S, 2 ?, and empirical parameters (S V, B V, S k and B k ). The positive magnitude of the limiting volumetric slopes, S V versus m 1/2 for this protic ionic liquid (PIL) in aqueous solutions, suggests that PIL-water interactions are weak. � 2015 Springer Science+Business Media New York.