1. Armarego, W. L. F.; Perrin, D. D.Purification of LaboratoryChemicals, 4th ed.; Butterworth-Heinemann: Oxford, 1996; p 334.
2. Preparation and Reaction of Lanthanide(II) Trifluoromethanesulfonates
3. One-Electron Reduction of Aromatic Ketones by Low-Valent Lanthanides. Isolation, Structural Characterization, and Reactivity of Lanthanide Ketyl Complexes
4. Protonation at the Aromatic Ring vs. at the Carbonyl Group of Lanthanide-Diaryl Ketone Dianion Species by Aryl Alcohols. Formation, Structural Characterization, and Reactivity of Lanthanide Aryloxide, Mixed Aryloxide/Alkoxide, and Aryloxide/Enolate Complexes
5. Typical experimental procedure follows (run 5 in Table 1): In a glovebox, a solution of benzophenone (36.4 mg, 0.2 mmol) in THF-d8(1 mL) was mixed with sodium (171 mg, 7.4 mmol) at room temperature. The reaction tube was removed from the glovebox and then flame-sealed under reduced pressure. The mixture was heated at 120 °C for 48 h. After cooling, the sealed tube was opened in an oxygen bag, and the solution was aspirated with an oxygen-containing gastight syringe. The reaction tube was washed with a small amount of THF, and the combined solution was passed through a short column of silica gel. After evaporation of the solvent, the crude product was subjected to preparative TLC with hexanes−ethyl acetate (6:1) as an eluent to give partially deuterated benzophenone (18.7 mg, 50%). A solid: IR (KBr) ν = 2269 (C−D), 1650 cm-1(CO);1H NMR (500 MHz, CDCl3, 25 °C, TMS)δ= 7.78−7.84 (m, 1.08 H, ortho-H), 7.56−7.62 (m, 1.50 H, para-H), 7.46−7.52 (m, 2.36 H, meta-H). The intensities are determined by the comparison with 1,4-dimethoxybenzene [δ= 6.84 (s, 4 H, aromatic H)] as an internal standard.13C NMR (125 Hz, CDCl3, 25 °C, TMS)δ= 196.70, 137.60, 137.51, 137.43, 132.38, 132.28, 132.17, 130.02, 130.01, 129.90, 129.73 [t, J (C−D) = 23.8 Hz], 129.63 [t, J (C−D) = 24.8 Hz], 128.25, 128.14, 128.03, 127.98, 127.85 [t, J (C−D) = 24.8 Hz]; MS (FAB)m/z(relative %) 194 (8), 193 (31), 192 (20), 191 (30), 190 (49), 189 (70), 188 (88), 187 (100), 186 (95), 185 (66), 184 (34), 183 (18), 182 (7). Partially deuterated benzhydrol (ca. 23%) and benzopinacol (ca. 9%) were also isolated. When the reaction was carried out in THF in a small sealed tube, 1,1-diphenyl-1-propanol (ca. 15%) was isolated as an additional byproduct, which must be formed by the coupling reaction of the benzophenone dianion with ethylene, one of the decomposition products of the THF anion.6