Carbazole is an aromatic heterocyclic organic compound. It has a tricyclic structure, consisting of two six-membered benzene rings fused on either side of a five-membered nitrogen-containing ring. The compound's structure is based on the indole structure, but in which a second benzene ring is fused onto the five-membered ring at the 2–3 position of indole (equivalent to the 9a–4a double bond in carbazole, respectively).
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Preferred IUPAC name
9H-Carbazole[1] | |
Other names
9-azafluorene
dibenzopyrrole diphenylenimine diphenyleneimide USAF EK-600 | |
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3956 | |
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ECHA InfoCard | 100.001.542 |
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102490 | |
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Properties | |
C12H9N | |
Molar mass | 167.211 g·mol−1 |
Density | 1.301 g cm−3 |
Melting point | 246.3 °C (475.3 °F; 519.5 K)[2] |
Boiling point | 354.69 °C (670.44 °F; 627.84 K)[2] |
−117.4 × 10−6 cm3 mol−1 | |
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H341, H351, H400, H411, H413 | |
P201, P202, P273, P281, P308+P313, P391, P405, P501 | |
Flash point | 220 °C (428 °F; 493 K)[2] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Carbazole is a constituent of tobacco smoke.[3]
A classic laboratory organic synthesis for carbazole is the Borsche–Drechsel cyclization.[4][5]
In the first step, phenylhydrazine is condensed with cyclohexanone to the corresponding imine. The second step is a hydrochloric acid-catalyzed rearrangement reaction and ring-closing reaction to tetrahydrocarbazole. In one modification, both steps are rolled into one by carrying out the reaction in acetic acid.[6] In the third step, this compound is oxidized by red lead to carbazole itself.
Another classic is the Bucherer carbazole synthesis, which uses a naphthol and an aryl hydrazine.[7]
A third method for the synthesis of carbazole is the Graebe–Ullmann reaction.
In the first step, an N-phenyl-1,2-diaminobenzene (N-phenyl-o-phenylenediamine) is converted into a diazonium salt which instantaneously forms a 1,2,3-triazole. The triazole is unstable and at elevated temperatures, nitrogen is released and the carbazole is formed.[8][9]
Aminoethylcarbazole is used in the production of pigment violet 23.