2,3,4-Trichloroaniline → 2,3,4-Trichlorophenylhydrazine

Fifty grams of 2,3,4-trichloroaniline was added portionwise to a solution of 200 ml of concentrated hydrochloric acid at approximately 0° C. To the reaction mixture was added 17.6 g of sodium nitrite dissolved in 100 ml of water dropwise over 1 hour. Next, 94.8 g of stannous chloride dissolved in 100 ml of concentrated hydrochloric acid was added dropwise to the reaction mixture over a 1 hour period while maintaining the temperature at approximately 0° C. The reaction mixture was stirred for approximately 1 hour at this temperature and then warmed to room temperature and stirred for 20 additional hours. The precipitated solid was collected by filtration and dried. The collected solid was added to a cold solution of 300 ml of 25% aqueous sodium hydroxide and this solution was stirred at approximately 5° C. for 1 hour. This aqueous solution was then extracted with ether and the organic phase was washed with water and saturated sodium chloride, and finally dried over anhydrous magnesium sulfate. The organic phase was evaporated under reduced pressure and the residue was recrystallized from ethanol to afford 35 g of 2,3,4-trichlorophenylhydrazine. Yield 66%. mp=138°-140° C.