Organic Syntheses, Coll. Vol. 3, p.351 (1955); Vol. 24, p.53 (1944).
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
). 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.
). The product should be used immediately (Note 4)
This ketazine is insoluble in petroleum ether
The reported melting point of diphenyldiazomethane
, but this melting point is shown only after the substance has been recrystallized from petroleum ether
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.
) 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.
This preparation is referenced from:
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