Thermodynamic properties of tetrabutylammonium iodide and tetrabutylammonium tetraphenylborate

The heat capacities of crystalline tetrabutylammonium iodide (TBAI) and tetrabutylammonium tetraphenylborate (TBATPhB) were determined over the temperature range 5−350 K by adiabatic vacuum calorimetry, generally with an uncertainty of ±0.2%. The experimental data were used to calculate the standard thermodynamic functions of TBAI and TBATPhB, namely, the heat capacity C(T)p°, enthalpy H°(T) − H°(0), entropy S°(T) and Gibbs function G°(T) − H°(0) at p° = 0.1 MPa for the range from T → 0 to T = 350 K. The standard entropy of formation ΔfS° TBAI and TBATPhB at T = 298.15 K was also determined. Thermodynamic characteristics of fusion and solid-state transition were determined by DSC, their comparison with literature data were carry out; numerical values of enthalpies and entropies of transitions were discussed in dependence of compounds composition.