Preparation
Over a 1-hr period, the temperature of a stirred solution of 150 gm (0.56 mole) of γ-bromopropylphthalimide, 91.7 gm (0.56 mole) of N-hydroxyphthalimide, 121 gm (1.2 moles) of triethylamine, and 700 ml of dimethyl formamide (DMF) is raised gradually to 90°C. The reaction mixture is cooled to room temperature and poured into 2 liters of water. The precipitate is collected (176 gm, 89.3%; m.p. 177-179°C). Upon re-crystallization (two times from glacial acetic acid, 8ml/gm), the melting point is raised to 178-180°C.
To a solution of 35.0 gm (0.1 mole) of 3-N-phthalimidopropyloxy-N-phthalimide in 200 ml of DMF maintained at 70°C is added 20 gm (0.4 mole) of hydrazine hydrate. After allowing the solution to cool to room temperature over a 1-hr period, 300 ml of cold water is added and the pH of the solution is adjusted to pH 3 with hydrochloric acid. The precipitated phthalhydrazide is separated by filtration; the filtrate is evaporated between 40 and 50°C under reduced pressure. The residue is dissolved in 1 liter of methanol and the resulting solution is passed through a column containing 1 liter of IRA-400 ion-exchange resin (in OH" form, and previously treated with methanol). After the eluant is collected the column is rinsed with 1.5 liters of methanol. The eluant and methanol rinsings are combined and concentrated under reduced pressure to afford 3.0 gm (45%), b.p. 110-115°C/3 mm Hg. On redistillation 2 gm (30%) of purified product is isolated; b.p. 99°C/40 mm Hg; n25D 1.4615; d254 0.999.
