The reactions of difluoroacetyl fluoride and trifluoroacetyl fluoride were investigated in the binary superacid HF/SbF₅ by low-temperature NMR spectroscopy. Whereas both haloacetyl fluorides form oxonium species after the addition of HF, the protonated acyl fluorides were not observed. Protonated 1,1,2,2-tetrafluoroethanol was isolated as a solid and represents an example of a protonated α-fluoroalcohol. The salt was characterized by low-temperature vibrational spectroscopy and single-crystal X-ray diffraction. [CHF₂CF₂OH₂][SbF₆] crystallizes in the triclinic space group P with two formula units per unit cell. Protonated perfluoroethanol is only stable in solution. The reactivity of both haloacyl fluorides is discussed based on quantum chemical calculations at the MP2/aug-cc-pVTZ-level of theory.

中文翻译：

---

超酸性介质中卤代乙酰氟的 HF 加成


采用低温核磁共振波谱研究了二氟乙酰氟和三氟乙酰氟在二元超强酸HF/SbF ₅ 中的反应。尽管两种卤代乙酰氟在添加 HF 后均形成氧鎓物质，但未观察到质子化的酰基氟。质子化 1,1,2,2-四氟乙醇以固体形式分离出来，代表质子化 α-氟醇的一个例子。通过低温振动光谱和单晶X射线衍射对该盐进行了表征。 [CHF ₂ CF ₂ OH ₂ ][SbF ₆ ] 在三斜空间群 P 中结晶每个单元格有两个公式单元。质子化的全氟乙醇仅在溶液中稳定。基于 MP2/aug-cc-pVTZ 理论水平的量子化学计算讨论了两种卤代酰氟的反应性。