Graebe-Ullmann synthesis

Carbazole

Names
IUPAC name 9H-carbazole
Other names 9-azafluorene dibenzopyrrole diphenylenimine diphenyleneimide USAF EK-600
Identifiers
CAS Number	86-74-8 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:27543 Y
ChemSpider	6593 Y
DrugBank	DB07301 Y
ECHA InfoCard	100.001.542
KEGG	C08060 Y
PubChem CID	6854
UNII	0P2197HHHN Y
InChI InChI=1S/C12H9N/c1-3-7-11-9(5-1)10-6-2-4-8-12(10)13-11/h1-8,13H Y Key: UJOBWOGCFQCDNV-UHFFFAOYSA-N Y InChI=1/C12H9N/c1-3-7-11-9(5-1)10-6-2-4-8-12(10)13-11/h1-8,13H Key: UJOBWOGCFQCDNV-UHFFFAOYAV
SMILES c1ccc2c(c1)c3ccccc3[nH]2
Properties
Chemical formula	C12H9N
Molar mass	167.21 g·mol−1
Density	1.301 g cm−3
Melting point	246.3 °C (475.3 °F; 519.5 K)
Boiling point	354.69 °C (670.44 °F; 627.84 K)
Magnetic susceptibility (χ)	−117.4 × 10−6 cm3 mol−1
Hazards
Flash point	220 °C (428 °F; 493 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

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).

Carbazole is a constituent of tobacco smoke.

A classic laboratory organic synthesis for carbazole is the Borsche–Drechsel cyclization.

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. In the third step, this compound is oxidized by red lead to carbazole itself. Another classic is the Bucherer carbazole synthesis.

A second 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 set free and the carbazole is formed.