3-Chloro-4-methoxyaniline → (3-Chloro-4-methoxyphenyl)hydrazine--hydrogen chloride (1/1)

A solution of sodium nitrite (6 g) in water (50 ml) was added dropwise to a solution of 3-chloro-4-methoxyaniline (10 g) in concentrated hydrochloric acid (30 ml) at 0° C. with stirring. After the addition was completed, the reaction mixture was stirred at the same temperature for 1 hour. A solution of stannous chloride dihydrate (50 g) in concentrated hydrochloric acid (30 ml) was added dropwise at 0° C. The resulting mixture was stirred for 2 hours at the same temperature. The resulting precipitate was collected by filtration, washed with ice water and dried in vacuo at 50° C. to afford (3-chloro-4-methoxyphenyl)hydrazine hydrochloride (11.5 g) as a yellow brown solid.