Preparation
l,2-Bis(phthalimidooxy)ethane is prepared according to a modified procedure of Β auer and Suresh [35d], in which 1 equiv. of 1,2-dibromoethane is alkylated with 2 equiv. of N-hydroxyphthalimide in DMF containing 6 equiv. of trimethylamine, to give an 84% yield of the desired product in the form of white needles. The white solid is recrystallized from hot DMF (this step is not essential because the crude product can be used in the next step of this preparation m.p. 248-249°C. (lit. [35d] m.p. 254°C.)
To 20.0 g (0.0568 mole) of l,2-bis(phthalimidioxy)ethane in 120 ml 95% ethanol at room temperature, while stirring, is added 5.81 ml of 95% hydrazine (0.174 mole) dropwise via a syringe over a 10-min period while nitrogen is kept over the reaction mixture. The reaction is mildly exothermic, and 5 min after the addition is complete, phthalhydrazide precipitated from the solution. The white precipitate is broken up and the mixture stirred for 2 hr, 50 ml 95% ethanol added, and filtered, and the phthalhydrazide is washed with 95% ethanol. The filtrates combined, and the solvent is removed under reduced pressure. Then 100 ml of methylene is added to the residue, and after storing at 10°C for 24 hr, the precipitated phthalhydrazide is filtered. The filtrate is dried (MgS04), and the solvent is removed under reduced pressure to give 3.39 g of a colorless liquid (65% yield).
