Patent ID: 7220858

Claim:
A method of preparing hydralazine hydrochloride, comprising the steps of: a. heating a first mixture of 1-phthalazinone with phosphorous oxychloride thereby providing 1-chlorophthalazine; b. contacting said 1-chlorophthalazine with an alkane comprised of from about 5 to about 7 carbon atoms; c. removing said alkane from said 1-chlorophthalazine; d. contacting said 1-chlorophthalazine obtained in step c with tetrahydrofuran; e. removing said tetrahydrofuran from said 1-chlorophthalzine; f. heating a second mixture containing 1-chlorophthalazine from step e and hydrazine hydrate thereby providing hydralazine; g. separating said hydralazine from said second mixture; h. contacting said hydralazine from step g with hydrochloric acid thereby providing hydralazine hydrochloride.