Information on Phenylhydrazine Hydrochloride Phenylhydrazine Hydrochloride is a off-white to brown coloured crystalline powder. It decomposes at 250oC. Phenylhydrazine Hydrochloride is soluble in water. Synthesis Manufacturing Process of Phenylhydrazine Hydrochloride Phenylhydrazine Hydrochloride is prepared by oxidation of aniline with sodium nitrite in the presence of Hydrochloric acid to give Diazonium salt, which is further reduced using Sodium Sulphite in the presence of Sodium Hydroxide to give Phenylhydrazine Hydrochloride Hydrochloride.