Preparation of benzopinacol
In a round-bottomed flask, 10 grams of benzophenone are dissolved in 60-70 ml of isopropyl alcohol by warming. Then the flask is filled to the neck with more of isopropyl alcohol and one drop of glacial acetic acid is added. If the acetic acid is omitted enough alkali may be derived from the glass to destroy completely the reaction product by the alkaline cleavage. The flask is tightly stoppered and inverted upside down in a beaker, by leaving it in the desk over night to see that there is no “dark ” reaction (alkaline cleavage). Then the flask is exposed to the best available sunlight. Since benzopinacol is but sparingly soluble in the alcohol, its formation can be followed from the separation around the walls of small, colorless crystals (benzophenone forms large, thick prisms). In the bright sunlight, the first crystals separate in about 5 hours, and the reaction is practically complete (95% yield) in four days. In the winter, the reaction may take as long as two weeks, and any benzophenone which crystallizes must be brought into solution by warming on the steam bath. When the reaction appears to be at an end, the flask is cooled if necessary and the benzopinacol is collected. The benzopinacol should be directly pure, with melting point 188-189° C.
Experiments in Organic Chemistry, L. F. Fieser, 203, 1941
Benzopinacol, Benzopinacole, Benzopinacone, Benzpinacone, Benzpinacol, 464-72-2, Tetraphenylethylene glycol, 1,1,2,2-Tetraphenylethane-1,2-diol, Benzophenone pinacol, Tetraphenyl-1,2-ethanediol, 1,1,2,2-Tetraphenyl-1,2-ethanediol, 1,2-Ethanediol, 1,1,2,2-tetraphenyl-, a,a’-bibenzhydrol, alpha,alpha’-Bibenzhydrol, 1,1,2,2-Tetraphenylethylene glycol, UNII-4VNT36L0QZ, NSC 120377, tetraphenylethane-1,2-diol, 4VNT36L0QZ, .alpha.,.alpha.’-Bibenzhydrol, MFEWNFVBWPABCX-UHFFFAOYSA-N, EINECS 207-356-8, AI3-09213, 1, 1,1,2,2-tetraphenyl-, 1,2,2-Tetraphenyl-1,2-ethanediol, AC1L3SUU, B9807_ALDRICH, Oprea1_328770, SCHEMBL36629, KSC589G9F, ACMC-209k78, AC1Q76X2, 88002_FLUKA, CTK4I9392, MFEWNFVBWPABCX-UHFFFAOYSA-, NSC1973, MolPort-000-736-158, BB_SC-5530, NSC-1973, ANW-30450, AR-1H6040, BBL010733, NSC120377, STK532695, ZINC01251729, AKOS005067843, MCULE-5732596925, NSC-120377, VZ31316, 1,2-Ethanediol,1,1,2,2-tetraphenyl-, 1,1,2,2-tetra(phenyl)ethane-1,2-diol, AC-10390, AN-45107, CJ-04804, LS-65541, M029, ZB016148, DB-051378, RT-000357, B1037, FT-0622728, ST50308179, 3B3-016446, 1082111-19-0, InChI=1/C26H22O2/c27-25(21-13-5-1-6-14-21,22-15-7-2-8-16-22)26(28,23-17-9-3-10-18-23)24-19-11-4-12-20-24/h1-20,27-28H