Each of three
250-ml., round-bottomed Pyrex flasks is charged with
8.4 g. (0.10 mole) of 2,3-dimethyl-2-butene (Note
1),
175 ml. of dichloromethane, and
50 ml. of an aqueous 5 M sodium hydroxide solution. The flasks are kept rather full, making more efficient use of the incident light. A
Teflon-covered magnetic stirring bar 2.5 cm. in length is added to each flask. Three
170 cm. by 90 cm. Pyrex crystallization dishes are partially filled with an ice–water mixture (Note
2), each dish is placed above a
Mag-Mix magnetic stirrer, and each flask is immersed in the
ice–water bath and held in place with a clamp. The three assemblies are arranged symmetrically around a
Hanovia quartz immersion well (Note
3) cooled with running tap water, containing a
Hanovia 450-watt, medium pressure, mercury lamp. The edge of each flask is placed approximately 1 cm. from the wall of the well. After
2.0 g. of iodoform is added to each flask, the mixtures are irradiated with stirring until the yellow color of the
iodoform disappears. This process is continued until
39.4 g. (0.100 mole) of iodoform, equally distributed between the flasks, has been consumed (Note
4). After the reaction is complete, the reaction mixtures are combined and the organic layer is separated, washed once with water, and dried over anhydrous
sodium sulfate. The solvent is removed with a
rotary evaporator and a
water pump. The residue is transferred to a
50-ml. flask, and
1.0 g. of sodium methoxide is added (Note
5). The mixture is distilled under reduced pressure in an apparatus with a
5-cm. Vigreux sidearm. The receiver is cooled in an ice–water bath and the first fraction, which boils at
45–48° (5 mm.),
n25D 1.5087, is collected, yielding
14.0–15.0 g. (
63–67%) of a clear distillate which should be stored in a refrigerator (Note
6) and (Note
7).