In a
3-l. round-bottomed flask is placed an intimate mixture of
486 g. (3 moles) of finely powdered anhydrous sodium succinate (Note
1) and
648 g. (4.1 moles) of finely ground phosphorus trisulfide (Note
2). The flask is fitted to a
100-cm. (40-in.) condenser set for distillation (Note
3), and a tube for introduction of
carbon dioxide is extended through the stopper to the center of the flask. The condenser is connected to a
2-l. flask cooled in an ice-salt mixture. The uncondensed gases are bubbled through two 2-l. flasks connected in series with the
receiving flask; each flask is cooled by an ice-salt mixture and contains 1 kg. of cracked ice and
200 cc. of 40 per cent sodium hydroxide solution.
The reaction flask is thoroughly swept out with
carbon dioxide (Note
4) while the flask is rotated to remove any air that is trapped by the solid. The flask is then connected to the condenser, and a slow stream of
carbon dioxide is passed through the system while the mixture is heated moderately for thirty minutes with a low Bunsen flame (Note
5), and then with the full force of the
Bunsen burner until no more yellow vapors are produced (about thirty minutes).
Carbon dioxide is passed through more rapidly during the latter heating period to ensure complete removal of the
thiophene (Note
6). The contents of the receiver and the
two absorption flasks are combined and steam-distilled from a
5-l. flask until no more oily drops are formed in the distillate. The
thiophene layer in the distillate is separated, dried successively over solid
sodium hydroxide and
sodium, and fractionated. The yield of product boiling at
83–86° is
63–75 g. (
25–30 per cent of the theoretical amount) (Note
7) and (Note
8).