Preparation of 4-benzyloxyphenylhydrazine: 200 grams 4-benzyloxyaniline hydrochloride was suspended in a mixture of 264 ml concentrated hydrochloric acid, 528 ml water and 732 grams crushed ice. A solution of 62.4 grams sodium nitrite in 136 ml water was added below the surface of the stirred suspension at -10-(+/-)2°C during 10 minutes. After stirring for 1 hour at 0°C, the suspension was treated with acid-washed charcoal and filtered.
The filtrate was cooled and maintained at -8°C while a solution of 500 grams of stannous chloride in 760 ml concentrated hydrochloric acid was added with stirring. The mixture was stirred for 2 hours at -8°C and the 4- benzyloxyphenylhydrazine hydrochloride which separated was filtered off and washed with water. The product was crystallized by adding 800 ml hot water to a 3 liter solution in ethanol and had a MP of 185° to 189°C (yield 168.5 grams, 79%).
