Abstract Tetra-n-butylammonium chloride (TBAC) semiclathrate hydrate crystals with hydration numbers n = (26.4–33.2) were prepared from TBAC aqueous solutions over the range of TBAC mole fractions (0.0060–0.0500). The thermodynamic and crystallographic properties of the TBAC hydrates were then investigated via ion chromatography, powder X-ray diffraction (PXRD), and differential scanning calorimetry. The crystal system of the TBAC hydrates with n = (26.4–33.2) was tetragonal, while the crystal structures (PXRD patterns) slightly varied with the hydration numbers. The dissociation enthalpies per guest mole (TBAC) gradually varied with the hydration numbers, from ~149 kJ mol−1 at n = 26.4 to ~187 kJ mol−1 at n = (33.1–33.2). These results suggest that the enthalpies per TBAC increased with greater hydrogen-bond formation in the TBAC hydrate crystals. The dissociation temperatures and dissociation enthalpies per H2O of the TBAC hydrates suggest that the hydrate crystals were most thermally stable at around n = 30 and slightly unstable with higher/lower hydration numbers.

中文翻译：

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热力学和结晶学特性取决于四正丁基氯化铵半笼形水合物中的水合数

摘要 在 TBAC 摩尔分数 (0.0060–0.0500) 范围内，由 TBAC 水溶液制备水合数 n = (26.4–33.2) 的四正丁基氯化铵 (TBAC) 半包合物晶体。然后通过离子色谱法、粉末 X 射线衍射 (PXRD) 和差示扫描量热法研究了 TBAC 水合物的热力学和晶体学性质。n = (26.4-33.2) 的 TBAC 水合物的晶体系统是四方晶系，而晶体结构（PXRD 图案）随水合数略有不同。每客体摩尔的解离焓 (TBAC) 随水合数而逐渐变化，从 n = 26.4 时的 ~149 kJ mol-1 到 n = (33.1–33.2) 时的 ~187 kJ mol-1。这些结果表明每个 TBAC 的焓随着 TBAC 水合物晶体中氢键形成的增加而增加。