Flash point data for Carbazole are not available; however, Carbazole is probably combustible.
Air & Water Reactions
Insoluble in water.
Carbazole is an extremely weak base. Carbazole is incompatible with strong oxidizing agents. Carbazole reacts with nitrogen oxides. Potassium hydroxide fusion yields a salt.
Dissolve carbazole (60g) in conc H2SO4 (300mL), extract with three 200mL portions of *benzene, then stir this into 1600mL of an ice-water mixture. The precipitate is filtered off, washed with a little water, dried, recrystallised from *benzene and then from pyridine/*benzene [Feldman et al. J Am Chem Soc 73 4341 1951]. It has also been recrystallised from EtOH or toluene, sublimed in vacuum, zone-refined, and purified by TLC. [UV: Armarego in Physical Methods in Heterocyclic Chemistry (Ed Katritzky, Academic Press) Vol III 158 1971, Beilstein 20/8 V 9.]
Carbazole and its derivatives are a class of important nitrogen-containing heterocyclic compounds possessing various unique properties and biological activity.
Carbazole is a colorless small scale crystal, insoluble in water and inorganic acid, slightly soluble in ethanol, ether, acetone, benzene (in high temperature), soluble in chloroform, glacial acetic acid, carbon disulfide, pyridine and furfural, etc. It has intense fluorescence and prolonged phosphorescence under ultraviolet light.
Diazotization from amino diphenylamine, and nitrogen gas heated off to generate carbazole. Reported by Graebe and Ullmann in 1896.
Co-thermal reaction of aryl hydrazine and naphthol in the presence of sodium bisulfite. Reported by Bucherer in 1904.
c. Borsche Drechsel:
Hydrazone is synthesized by condensation of Benzoquinone and cyclohexanone, and the latter cyclized to tetrahydrocarbazole under acidic conditions and then catalyzed by dehydrogenation to generate carbazole. Reported by Drechsel and Borsche in 1868 and 1904 respectively.
Thanks to the development of the catalytic dehydrogenation method, the Borsche method has become a carbazole synthetic route with simple operation, mild conditions, low cost and high yield, and has a high industrial production value.
Because of its unique structure and physicochemical properties, carbazole has aroused great interest among researchers. In recent years, novel mono- and poly-substituted carbazole derivatives have been found to have good anti-tumor and anti-convulsant activities, showing broad application prospects. The demand for carbazole and its derivatives has been increasing. In the last decade of the 20th century, a large number of novel precious metals and transition metal catalysts have been used in the synthesis of carbazoles and their derivatives, which greatly enriched the synthetic methods and lay the foundation of synthesizing more complex carbazole derivatives. Nowadays, not only carbazole, but tens of thousands of carbazole derivatives are synthesized by new methods, and are widely used in the pharmaceutical and dye industries.
Important dye intermediate. Used in making photographic plates sensitive to ultraviolet light. Reagent for lignin, carbohydrates, and formaldehyde.
Sulfuric acid method
Dissolve crude anthracene in chlorobenzene or other solvents to remove soluble phenanthrenes, quinones, etc. Insoluble anthracene and carbazoles are then reacted with concentrated sulfuric acid, and then carbazole sulfate is generated departing from the anthracene. The carbazole sulfate is hydrolyzed, filtered and dried to obtain carbazole.
Dissolve crude anthracene with heavy benzene, and remove soluble phenanthrene, quinone and other substances. Insoluble anthracene and carbazole are rectified in a rectification tower to obtain a mixture containing 85 to 90% of carbazole with a yield of 65%.
Pyridine solvent method
Dissolve crude anthracene with heavy benzene, and remove soluble phenanthrene, quinone and other substances. Then pyridine is used as a solvent to filter off insoluble anthracene at 90°C, and the filtrate is then crystallized to obtain crude carbazole. The crude carbazole can be treated with chlorobenzene or other solvents to obtain carbazole with yield of 97 to 99%.
White crystals, plates, leaflets or light tan powder. Sublimes readily. Exhibits strong fluorescence and long phosphorescence on exposure to ultraviolet light.
white crystals or light brown powder