Org. Synth. 1944, 24, 53
DOI: 10.15227/orgsyn.024.0053
DIPHENYLDIAZOMETHANE
[Methane, diazodiphenyl-]
Submitted by Lee Irvin Smith and Kenneth L. Howard.
Checked by H. R. Snyder, R. L. Rowland, and H. J. Sampson, Jr..
1. Procedure
In a pressure bottle are placed 19.6 g. (0.1 mole) of benzophenone hydrazone (Note 1), 22 g. (0.1 mole) of yellow oxide of mercury, and 100 ml. of petroleum ether (b.p. 30–60°). The bottle is closed, wrapped in a wet towel, and shaken mechanically at room temperature for 6 hours. The mixture is then filtered to remove mercury and any benzophenone azine (Note 2), and the filtrate is evaporated to dryness under reduced pressure at room temperature. The crystalline residue of diphenyldiazomethane melts when its temperature reaches that of the room (Note 3), but it is difficult to purify and this product is pure enough for all practical purposes. The material weighs 17.3–18.6 g. (89–96%). The product should be used immediately (Note 4).
2. Notes
1.
Benzophenone hydrazone is most readily prepared from
benzophenone (40 g., 0.22 mole) in 150 ml. of absolute ethanol with
41.2 g. (0.824 mole) of 100% hydrazine; the mixture is heated under reflux for 10 hours. On cooling in ice, colorless
benzophenone hydrazone separates. The yield is
37.5 g. (
87%), m.p.
97–98°.
If anhydrous
hydrazine is not available, it may be prepared by the method described in
Org. Syntheses, 24, 53 (1944).
2.
This ketazine is insoluble in
petroleum ether.
3.
The reported melting point of
diphenyldiazomethane is
29–30°, but this melting point is shown only after the substance has been recrystallized from
petroleum ether.
4.
On standing,
diphenyldiazomethane decomposes to yield
benzophenone azine. In one of the checkers' runs the product was stored at room temperature; after 2 days, crystals of the azine were visible. The product at this stage was assayed by treatment with
benzoic acid; addition of 6.8 g. of the diazo compound in a thin stream to a solution of
17 g. of benzoic acid in 90 ml. of ether, and, after 30 minutes, extraction of the excess
benzoic acid with dilute
sodium hydroxide followed by distillation of the
ether gave
7.4 g. (
75%) of crude
benzohydryl benzoate melting at
83–85°. In the same procedure the freshly prepared diazo compound gave a quantitative yield of the crude ester.
3. Discussion
Diphenyldiazomethane has been prepared only by oxidation of
benzophenone hydrazone.
1 The procedure given above is that of Staudinger, Anthes, and Pfenninger, with minor changes.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
petroleum ether
oxide of mercury
benzohydryl benzoate
ethanol (64-17-5)
ether (60-29-7)
sodium hydroxide (1310-73-2)
Benzoic acid (65-85-0)
mercury (7439-97-6)
Benzophenone (119-61-9)
hydrazine (302-01-2)
Diphenyldiazomethane (883-40-9)
Methane, diazodiphenyl-
benzophenone hydrazone (5350-57-2)
benzophenone azine (983-79-9)
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