A suspension of 13 g of hydrazinophthalazine in 500 ml of anhydrous ethanol
is cooled, under agitation to a temperature of -10°C. To the suspension is
added dropwise within 30 min a solution of 4.5 g of ethyl chlorocarbonate in
150 ml of anhydrous ethanol and the reaction mass is agitated for about 2
hours, maintaining a temperature of -10°C. The temperature is then raised to
about 20°C and stirring is continued for 2 hours, whereupon heating is applied
and boiling is maintained for 15 min. After cooling, the separated 1-
hydrazinophthalazine hydrochloride is filtered and washed with anhydrous
ethanol.
The filtrate is evaporated to a dry state under decreased pressure at a
temperature of below 50°C. The residue in a quantity of 8.5 g is dissolved in a
boiling solution of 3 ml of concentrated hydrochloric acid in 15 ml of water,
and after adding 5 ml of 90%-ethanol the solution is cooled to a temperature
of below 0°C.
The separated 1-carboethoxyhydrazinophthalazine hydrochloride is filtered and
washed with anhydrous ethanol. 11.5 g of a raw product are obtained which
for the purpose of purification are dissolved in 15 ml of boiling water with an
addition of 10 ml of 96%-ethanol and after cooling to below 0°C, the pure 1-
carboethoxyhydrazinophthalazine hydrochloride is filtered. 9.8 g of the are
obtained.
