In a
500-cc. round-bottomed flask are placed
60 cc. of 50 per cent aqueous potassium hydroxide solution and
200 cc. of ether. The mixture is cooled to 5°, and
20.6 g. (0.2 mole) of nitrosomethylurea (p. 461) is added with shaking. The flask is fitted with a
condenser set for distillation. The lower end of the condenser carries an
adapter passing through a two-holed rubber stopper and dipping below the surface of
40 cc. of ether contained in a
300-cc. Erlenmeyer flask and cooled in an ice-salt mixture. The exit gases are passed through a second
40-cc. portion of ether likewise cooled below 0°. The reaction flask is placed in a
water bath at 50° and brought to the boiling point of the
ether with occasional shaking. The
ether is distilled until it comes over colorless, which is usually the case after two-thirds of the ether has been distilled.
Under no circumstances should all the ether be distilled. The combined
ether solutions in the receiving flasks contain from
5.3 to 5.9 g. of
diazomethane (
63–70 per cent of the theoretical amount) (Note
1) and (Note
2), which is sufficiently dry for most purposes (Note
3).