Abstract Large organic guest molecules (LOGMs) have been reported to form clathrate hydrates with help gas molecules. Specific LOGMs with a hydroxyl group show an ‘inhibition effect’ on the thermodynamic equilibria of clathrate hydrates, forcing the phase equilibrium curve to shift to a relatively unstable region of lower temperature and higher pressure conditions. Here, we introduce a potential candidate, 3-hydroxytetrahydrofuran (3-OH THF), which has a sole different functional group from tetrahydrofuran (THF), a powerful thermodynamic promoter, to examine the effect of the hydroxyl group on the phase equilibria of clathrate hydrates. The powder X-ray diffraction patterns and Raman spectra reveal that both sI and sII clathrate hydrates can be formed depending on the type of help gas molecules (methane, nitrogen, oxygen, and carbon dioxide). Additionally, the phase equilibria of binary (3-OH THF + help gases) clathrate hydrates are measured to check the degree of inhibition due to the substituted hydroxyl group. The carbon dioxide, unlike other gaseous guest molecules, prevented LOGMs of 3-OH THF from occupying sII large cages, and thus we only observed the appearance of pure carbon dioxide hydrate.

中文翻译：

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3-羟基四氢呋喃抑制天然气水合物：光谱鉴定和水合物相平衡

摘要 据报道，大有机客体分子 (LOGMs) 与辅助气体分子形成笼形水合物。具有羟基的特定 LOGM 对笼形水合物的热力学平衡显示出“抑制作用”，迫使相平衡曲线转移到较低温度和较高压力条件下的相对不稳定区域。在这里，我们介绍了一种潜在的候选物 3-羟基四氢呋喃 (3-OH THF)，它与四氢呋喃 (THF) 具有唯一不同的官能团，这是一种强大的热力学促进剂，以检查羟基对包合物相平衡的影响水合物。粉末 X 射线衍射图和拉曼光谱表明，根据辅助气体分子（甲烷、氮气、氧气和二氧化碳）的类型，可以形成 sI 和 sII 笼形水合物。此外，测量二元（3-OH THF + 辅助气体）笼形水合物的相平衡，以检查由于取代羟基的抑制程度。与其他气态客体分子不同，二氧化碳阻止了 3-OH THF 的 LOGMs 占据 sII 大笼子，因此我们只观察到纯二氧化碳水合物的出现。