重氮化反应 氨基变叠氮 2-NITROCARBAZOLE.pdfVIP

Organic Syntheses, Coll. Vol. 5, p.829 (1973); Vol. 46, p.85 (1966). 2-NITROCARBAZOLE [Carbazole, 2-nitro] Submitted by G. David Mendenhall and Peter A. S. Smith1. Checked by Howard A. Harris and Kenneth B. Wiberg. 1. Procedure A. o-Aminobiphenyl. A Parr bottle is charged with 60 g. (0.30 mole) of o-nitrobiphenyl (Note 1), 3 g. of 5% palladium-on-carbon catalyst (Note 2), and 200 ml. of 95% ethanol. The mixture is shaken with hydrogen under 25–50 p.s.i. until the gas is no longer absorbed (about 70 minutes), the catalyst is filtered from the hot solution and washed with 20 ml. of ethanol, and the filtrates are poured in a thin stream into 1 l. of ice water contained in a 2-l. Erlenmeyer flask (Note 3). After standing for 20 minutes the white solid is filtered with suction, pressed to remove excess water, and allowed to dry in air. The yield of essentially pure o-aminobiphenyl is 48–51 g. (94–100%), m.p. 43–45.5°. B. o-Amino-p-nitrobiphenyl. Concentrated sulfuric acid (400 ml.) is placed in a 1-l. round-bottomed flask fitted with a mechanical stirrer and a thermometer. Stirring is begun, and 45.0 g. (0.27 mole) of powdered o-aminobiphenyl is added all at once through a powder funnel. When the amine has dissolved, the flask is placed in an ice-salt bath and its contents cooled to a temperature between 0° and −5°. A mixture of 30 ml. of concentrated sulfuric acid and 11.0 ml. of fuming nitric acid (density 1.5) is then added dropwise from a separatory funnel while the temperature is kept below 0°. The addition requires about an hour, and stirring is continued 45 minutes longer. The liquid is poured onto 1.5 kg. of ice in a 4-l. beaker and treated carefully until neutral with a solution of 580 g. (14.5 moles) of sodium hydroxide in 1.5 l.