Org. Synth. 1932, 12, 72
DOI: 10.15227/orgsyn.012.0072
THIOPHENE
Submitted by Ross Phillips
Checked by Roger Adams and H. D. Cogan.
1. Procedure
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).
2. Notes
1.
The
sodium succinate, prepared from
succinic acid, was dried in shallow pans on a
water bath for several days.
2.
If
phosphorus trisulfide is not obtainable, it may be prepared by the following method developed by A. M. Griswold: An intimate mixture of the calculated amounts of finely powdered
sulfur and red phosphorus is placed in an
earthenware flower pot, sealed at the bottom with a
cork. The pot is imbedded in a
bucket of sand, and a heavily weighted cover is held in readiness over the top. A lighted match is dropped into the mixture, the lid is quickly put in place, and the crevices are sealed with sand. The reaction should be carried on out-of-doors as it is extremely vigorous and often gives an excellent display of fireworks. When thoroughly cool, the flower pot is broken and the contents are removed and kept in a
tightly stoppered bottle. It is desirable to keep this material for some time before grinding, as the freshly prepared product is not completely crystallized and is difficult to grind.
3.
Because of the rapid evolution of a large volume of gas, the tube connecting the flask to the condenser should be about 2 cm. in diameter and all stoppers should fit tightly.
4.
If the air is not completely removed before heating the flask, the reaction may take place with explosive violence.
5.
The checkers found that continual heating was necessary during this part of the preparation.
6.
The stopper should not be removed from the reaction flask until the flask is quite cool, in order to prevent ignition of the excess
phosphorus trisulfide on contact with the air. The hard mass remaining may be softened by treatment with hot water, after which it may be broken up and shaken out.
7.
The freshly prepared product often deposits a small amount of a brown precipitate on standing for some time. If this is removed by filtration, no further precipitate is formed.
8.
Larger runs have been made successfully, but there is greater danger of a violent reaction.
3. Discussion
Thiophene is found in small amounts in coal gas and
benzene.
1 It has been prepared by passing
ethylene or
acetylene into boiling
sulfur;
2 by passing
ethyl sulfide through a hot tube;
3 by passing
ethylene or illuminating gas over hot pyrites;
4 by heating
succinic anhydride with
phosphorus pentasulfide;
5 by treatment of
erythritol with
phosphorus pentasulfide;
6 by treatment of
succinic aldehyde with
phosphorus trisulfide;
7 by passing
acetylene over pyrites at 300°;
8 by treatment of
sodium succinate with
phosphorus trisulfide;
9 by passing
acetylene and
hydrogen sulfide over
bauxite at 320°, or over
nickel hydroxide at 300°;
10 and by passing
furan and
hydrogen sulfide over heated
alumina.
11
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
red phosphorus
alumina
phosphorus trisulfide
bauxite
acetylene (74-86-2)
Benzene (71-43-2)
sodium hydroxide (1310-73-2)
hydrogen sulfide (7783-06-4)
sulfur (7704-34-9)
carbon dioxide (124-38-9)
Succinic acid (110-15-6)
sodium (13966-32-0)
ethylene (9002-88-4)
Furan (110-00-9)
Thiophene (110-02-1)
Succinic anhydride (108-30-5)
sodium succinate (150-90-3)
phosphorus pentasulfide (1314-80-3)
ethyl sulfide (352-93-2)
erythritol
succinic aldehyde (638-87-9)
nickel hydroxide (12054-48-7)
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