Belarusian State University, Chemistry Faculty, 14 Leningradskaya Str., 220030 Minsk, Belarus.
J Phys Chem B. 2009 Nov 5;113(44):14742-6. doi: 10.1021/jp907073w.
The enthalpy of the 1-butyl-3-methylimidazolium bromide [C(4)mim]Br ionic liquid synthesis reaction 1-methylimidazole (liq) + 1-bromobutane (liq) --> [C(4)mim]Br (liq) was determined in a homemade small-volume isoperibol calorimeter to be Delta(r)H degrees (298) = -87.7 +/- 1.6 kJ x mol(-1). The activation energy for this reaction in a homogeneous system E(A) = 73 +/- 4 kJ x mol(-1) was found from the results of calorimetric measurements. The formation enthalpies for the crystalline and liquid [C(4)mim]Br were determined from the calorimetric data: Delta(f)H degrees (298)(cr) = -178 +/- 5 kJ x mol(-1) and Delta(f)H degrees (298)(liq) = -158 +/- 5 kJ x mol(-1). The ideal-gas formation enthalpy of this compound Delta(f)H degrees (298)(g) = 16 +/- 7 kJ x mol(-1) was calculated using the methods of quantum chemistry and statistical thermodynamics. The vaporization enthalpy of [C(4)mim]Br, Delta(vap)H degrees (298) = 174 +/- 9 kJ x mol(-1), was estimated from the experimental and calculated formation enthalpies. It was demonstrated that vapor pressure of this ionic liquid cannot be experimentally determined.
1-丁基-3-甲基咪唑溴盐 [C(4)mim]Br 离子液体的合成反应 1-甲基咪唑（液体）+ 1-溴丁烷（液体）→ [C(4)mim]Br（液体）的焓变在自制的小体积等压量热计中测定为 ΔrH°(298) = -87.7 ± 1.6 kJ/mol。从量热测量结果得出，该均相体系反应的活化能 E(A) = 73 ± 4 kJ/mol。从量热数据确定了结晶和液体 [C(4)mim]Br 的生成焓：ΔfH°(298)(cr) = -178 ± 5 kJ/mol 和 ΔfH°(298)(liq) = -158 ± 5 kJ/mol。使用量子化学和统计热力学方法计算了该化合物的理想气体生成焓 ΔfH°(298)(g) = 16 ± 7 kJ/mol。[C(4)mim]Br 的蒸发焓 ΔvapH°(298) = 174 ± 9 kJ/mol 是从实验和计算生成焓估算的。结果表明，无法通过实验测定该离子液体的蒸气压。
