1911 Encyclopædia Britannica/Carbazol

CARBAZOL, C₁₂H₉N, a chemical constituent of coal-tar and crude anthracene. From the latter it may be obtained by fusion with caustic potash when it is converted into carbazol-potassium, which can be easily separated by distilling off the anthracene. It may be prepared synthetically by passing the vapours of diphenylamine or aniline through a red-hot tube; by heating diorthodiaminodiphenyl with 25% sulphuric acid to 200° C. for 15 hours; by heating orthoaminodiphenyl with lime; or by heating thiodiphenylamine with copper powder. It is also obtained as a decomposition product of brucine or strychnine, when these alkaloids are distilled with zinc dust. It is easily soluble in the common organic solvents, and crystallizes in plates or tables melting at 238° C. It is a very stable compound, possessing feebly basic properties and characterized by its ready sublimation. It distils unchanged, even when the operation is carried out in the presence of zinc dust. On being heated with caustic potash in a current of carbonic acid, it gives carbazol carbonic acid C₁₂H₈N·COOH; melted with oxalic acid it gives carbazol blue. It dissolves in concentrated sulphuric acid to a clear yellow solution. The potassium salt reacts with the alkyl iodides to give N-substituted alkyl derivatives. It gives the pine-shaving reaction, in this respect resembling pyrrol (q.v.).