Dept. of Life Science, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark.
Phys Chem Chem Phys. 2011 Jan 21;13(3):1182-8. doi: 10.1039/c0cp00494d. Epub 2010 Nov 12.
Interactions between methyl tert-butyl ether (MTBE) and water have been investigated by scanning calorimetry, isothermal titration calorimetry, densitometry, IR-spectroscopy, and gas chromatography. The solubilization of MTBE in water at 25 °C at infinite dilution has ΔH° = -17.0 ± 0.6 kJ mol(-1); ΔS° = -80 ± 2 J mol(-1) K(-1); ΔC(p) = +332 ± 15 J mol(-1) K(-1); ΔV° = -18 ± 2 cm(3) mol(-1). The signs of these thermodynamic functions are consistent with hydrophobic interactions. The occurrence of hydrophobic interaction is further substantiated as IR absorption spectra of MTBE-water mixtures show that MTBE strengthens the hydrogen bond network of water. Solubilization of MTBE in water is exothermic whereas solubilization of water in MTBE is endothermic with ΔH° = +5.3 ± 0.6 kJ mol(-1). The negative mixing volume is explained by a large negative contribution due to size differences between water and MTBE and by a positive contribution due to changes in the water structure around MTBE. Henry's law constants, K(H), were determined from vapor pressure measurements of mixtures equilibrated at different temperatures. A van't Hoff analysis of K(H) gave ΔH(H)° = 50 ± 1 kJ mol(-1) and ΔS(H)° = 166 ± 5 J mol(-1) K(-1) for the solution to gas transfer. MTBE is excluded from the ice phase water upon freezing MTBE-water mixtures.
已通过扫描量热法、等温滴定量热法、密度法、红外光谱法和气相色谱法研究了甲基叔丁基醚（MTBE）与水之间的相互作用。在 25°C 下无限稀释时，MTBE 在水中的溶解度的 ΔH°=-17.0±0.6 kJ mol(-1)；ΔS°=-80±2 J mol(-1) K(-1)；ΔC(p)=+332±15 J mol(-1) K(-1)；ΔV°=-18±2 cm(3) mol(-1)。这些热力学函数的符号与疏水相互作用一致。IR 吸收光谱表明 MTBE 增强了水的氢键网络，进一步证实了疏水相互作用的发生。MTBE 在水中的溶解是放热的，而水在 MTBE 中的溶解是吸热的，ΔH°=+5.3±0.6 kJ mol(-1)。由于水和 MTBE 之间的尺寸差异以及 MTBE 周围水结构的变化导致混合体积为负。Henry 常数 K(H)是通过平衡在不同温度下的混合物的蒸气压测量来确定的。对 K(H)的 van't Hoff 分析得出，对于气液转移的溶液，ΔH(H)°=50±1 kJ mol(-1)，ΔS(H)°=166±5 J mol(-1) K(-1)。在 MTBE-水混合物冻结时，MTBE 被排除在冰相水中。
