Preparation
To a flask equipped as in Preparation 2-6 is added 162.0 gm (1.0 mole) of ethyl orthoacetate, 42.0 gm (1.0 mole) of cyanamide, and 134.0 gm (2.0 moles) of acetic anhydride. The reaction mixture is heated to 130-140°C and the ethyl acetate and acetic acid are distilled over. The heat is removed until the initial vigorous reaction subsides and then the heating is continued at 135-140°C until most of the remaining ethyl acetate and acetid acid have distilled over (approx. 1 hr). The residue is then distilled under reduced pressure to afford 100.8 gm (90%), b.p. 90-95°C (20 mm Hg).
