Thirty grams (0.134 mole) of benzil hydrazone (Note
1) is mixed in a mortar with
60 g. (0.28 mole) of yellow mercuric oxide and
15 g. of anhydrous sodium sulfate (Note
2). The mixture is introduced into a
500-cc. glass-stoppered bottle and covered with
200 cc. of absolute ether (Note
3).
Four cubic centimeters of a cold, saturated solution of alcoholic potassium hydroxide is added to catalyze the reaction (Note
4), and the mixture is shaken for ten to fifteen minutes. The solution is filtered by gravity through a fine paper, and the residue is washed several times with
ether until the liquid is only slightly colored. The combined ethereal extracts are evaporated to dryness at the pressure of the
water pump by heating the flask in a
water bath to a temperature not greater than 40° (Note
5). The yellow, crystalline material is dried on a
porous plate and recrystallized from anhydrous
ether. The yield of
azibenzil which melts at about
79° with decomposition is
26–28 g. (
87–94 per cent of the theoretical amount) (Note
6).