Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Analytische Chemie, Freiburg, Germany.
Phys Chem Chem Phys. 2011 Apr 7;13(13):6184-91. doi: 10.1039/c0cp02596h. Epub 2011 Feb 25.
The syntheses of the perfluorinated alcohols (F(5)C(6))(F(3)C)(2)COH (1) and (F(5)C(6))(C(5)F(10))COH (2) are described. Both compounds were prepared in reasonable yields (1: 65%, 2: 85%) by reacting the corresponding ketone with C(6)F(5)MgBr, followed by acidic work-up. The alcohols were characterized by NMR, vibrational spectroscopy, single-crystal X-ray diffraction, acidity measurements and gas-phase electron diffraction. A combination of appropriate 2D NMR experiments allowed the unambiguous assignment of all signals in the (19)F spin systems, of which that of 2 was especially complex. High acidity of the alcohols is indicated by acidity measurements as well as the calculated gas phase acidities. It is also supported by the crystal structure of 2, which exhibits only a single weak intermolecular hydrogen bridge with an O...O distance of 301 pm. This shows the low donor strength of the oxygen atom in the compound, which is partly compensated through formation of two intramolecular CF...H contacts of 220 and 232 pm length to the proton not involved in the hydrogen bridge. The pK(a) values in acetonitrile are 22.2 for 1 and 22.0 for 2; their calculated gas phase acidities are 1367 and 1343 kJ mol(-1) (MP2/TZVPP level).
全氟醇（F(5)C(6))(F(3)C)(2)COH（1）和（F(5)C(6))(C(5)F(10))COH（2）的合成描述如下。这两种化合物都是通过将相应的酮与 C(6)F(5)MgBr 反应，然后进行酸性处理，以合理的产率（1：65%，2：85%）制备的。通过 NMR、振动光谱、单晶 X 射线衍射、酸度测量和气相电子衍射对醇进行了表征。适当的 2D NMR 实验组合允许对（19）F 自旋系统中的所有信号进行明确分配，其中 2 的信号尤其复杂。酸度测量和计算的气相酸度表明醇具有高酸度。这也得到了 2 的晶体结构的支持，其中仅显示出与质子的单个弱分子间氢键，O...O 距离为 301 pm。这表明化合物中氧原子的供电子强度较低，部分通过形成两个与不参与氢键的质子的 220 和 232 pm 长度的分子内 CF...H 接触得到补偿。在乙腈中的 pK(a)值为 1 为 22.2，2 为 22.0；它们的计算气相酸度分别为 1367 和 1343 kJ mol(-1)（MP2/TZVPP 水平）。
