In a
500-ml. round-bottomed flask fitted with a
reflux condenser and a drying tube leading to a gas-absorption
trap2 are placed
234 g. (1.1 mole) of phosphorus pentachloride (Note
1) and
65 g. (0.5 mole) of itaconic acid (Note
2). The reagents are mixed by shaking the flask; after a few minutes a vigorous reaction commences, resulting in partial liquefaction of the mixture and copious evolution of
hydrogen chloride. When the initial reaction subsides, the mixture is gently heated to cause reflux of
phosphorus oxychloride until all the solid dissolves; then heating is continued for an additional 15 minutes (Note
3). The
reflux condenser is replaced by a
12-in. Vigreux column, and the
phosphorus oxychloride is removed by distillation at reduced pressure provided by a
water aspirator (Note
4), the major portion coming over at about 45°/85 mm. When all the
phosphorus oxychloride has been removed, the pressure is reduced (
vacuum pump) and the material boiling at
70–75°/2 mm. is collected. Liquid boiling in this range weighs
50–55 g., representing a yield of
60–66%. This material,
nD20 1.4915,
nD25 1.4900, is pure enough for most purposes, but it may be further refined by distillation through a packed column, yielding
47–53 g. of a water-white liquid,
nD20 1.4919, boiling at
71–72°/2 mm.