Org. Synth. 1928, 8, 24
DOI: 10.15227/orgsyn.008.0024
BENZOHYDROL
Submitted by F. Y. Wiselogle and H. Sonneborn, III.
Checked by C. S. Marvel and J. F. Kaplan.
1. Procedure
In a 3-l. round-bottomed flask fitted with a mechanical stirrer are placed 200 g. of technical flake sodium hydroxide, 200 g. of benzophenone, 2 l. of 95 per cent alcohol, and 200 g. of technical zinc dust. The stirrer is started and the mixture slowly warms to about 70° spontaneously. After two to three hours the mixture, which has started to cool, is filtered with suction, and the residue is washed twice with 100-cc. portions of hot alcohol (Note 1).
The filtrate is poured into five volumes of ice water acidified with about 425 cc. of concentrated commercial hydrochloric acid. The benzohydrol separates as a white crystalline mass and is filtered by suction. The yield of crude air-dried product melting at 65° is 194–196 g. (96–97 per cent of the theoretical amount). From 200 g. of crude product in 200 cc. of hot alcohol there is obtained, after cooling in an ice-salt mixture, filtering, and drying, 140–145 g. of product melting at 68°. The benzohydrol remaining in the mother liquors may be precipitated with water.
2. Notes
1.
The filtered
zinc dust is inflammable; it must not be allowed to dry in contact with combustible material.
3. Discussion
Benzohydrol can be prepared by reducing
benzophenone with
sodium amalgam;
1 with metallic
calcium and alcohol;
2 with
hydrogen in the presence of a catalyst;
3 with
zinc, aluminum, or sodium in strongly alkaline solutions;
4 with
zinc dust and alcoholic potassium hydroxide solution;
5 electrolytically;
6 with
magnesium and absolute alcohol;
7 with
magnesium and ammonium chloride in
95 per cent alcohol;
7 with
isopropyl alcohol and a little sodium isopropoxide;
8 and with
aluminum isopropoxide.
9
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Benzohydrol
alcohol (64-17-5)
hydrochloric acid (7647-01-0)
ammonium chloride (12125-02-9)
hydrogen (1333-74-0)
sodium hydroxide (1310-73-2)
magnesium (7439-95-4)
aluminum (7429-90-5)
potassium hydroxide (1310-58-3)
Benzophenone (119-61-9)
zinc (7440-66-6)
calcium (7440-70-2)
sodium (13966-32-0)
isopropyl alcohol (67-63-0)
sodium isopropoxide (683-60-3)
aluminum isopropoxide
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