The phenylhydrazine hydrochloride may be purified by crystallizing from water. A 600-cc. portion of water is used for 100 g. of crude hydrochloride, and the solution boiled a short time with a few grams of animal charcoal. After filtering, 200 cc. of concentrated hydrochloric acid are added, and the mixture cooled to 0'0. Pure white crystals in a yield of 85-90 g. are obtained.
Rubber gloves should be worn when working with large quantities of phenylhydrazine, since the product may cause serious injury to the skin. The vapors of phenylhydrazine should not be inhaled.
3. Other Methods of Preparation
Phenylhydrazine has been prepared by the reduction of benzene diazonium salts with sulfites;[1] by the reduction of benzene diazonium chloride with stannous chloride;[2] by the reduction of benzene diazonium hydrate with zinc or sulfur dioxide;[3] by the reduction of sodium benzene diazotate with sodium stannite;[4] by the reduction of diazoamino benzene;[5] by the reduction of nitrosophenyl hydroxylamine or its methyl ether;[6] and by the action of hydrazine hydrate on phenol.[7]
[1] Ann. 190, 79 (3878); Ber. 20, 2463, (1887).
[2] Ber. 16, 2976 (1883); 17, 572, footnote (1884).
[3] Ber. 31, 346 (1898).
[4] Ber. 36, 816 (1903).
[5] Ber. 31, 582 (1898).
[6] Ann. 190, 77 (1878).