Org. Synth. 1928, 8, 112
DOI: 10.15227/orgsyn.008.0112
TRIMETHYLENE CHLOROHYDRIN
[1-Propanol, 3-chloro-]
Submitted by C. S. Marvel and H. O. Calvery.
Checked by H. T. Clarke and M. R. Brethen.
1. Procedure
A
100-cc. round-bottomed, wide-mouthed flask (or a
large test tube 18 cm. long and 4.5 cm. wide) is fitted with a
rubber stopper carrying a
separatory funnel, a
thermometer, an
inlet tube reaching almost to the bottom of the flask, and an
outlet tube leading to a
condenser set for downward distillation. A
receiver consisting of a suction flask is attached tightly to the end of the condenser, and the side arm of the receiver is attached to a
reflux condenser. A tube is led from the top of the condenser to the
hood in order to take care of excess
hydrogen chloride during the distillation, or a
gas-absorption trap (Fig. 7, p. 97) can be used for this purpose. About
25–30 cc. of trimethylene glycol (b.p.
210–215°) is placed in the flask and heated by means of an
oil or metal bath to 150–170°. A
very rapid stream of dry
hydrogen chloride (Note 1) is now led into the hot glycol through the inlet tube. A reddish distillate consisting of water,
trimethylene chlorohydrin,
hydrogen chloride, and some unchanged glycol begins to distil. As rapidly as the glycol is used up in the reaction flask, more is added from the separatory funnel. It is always advisable to keep the amount of material in the reaction flask as small as possible. The rate at which the
hydrogen chloride is passed through the flask controls the reaction and also has a marked effect on the yield
(Note 2). The best results are obtained by passing in the gas rapidly enough to use up
2–3 cc. of trimethylene glycol in one minute. The process is continuous and can be run indefinitely without changing the apparatus. The weight of crude distillate from
1800 g. of trimethylene glycol is usually
2300–2500 g.To obtain the
trimethylene chlorohydrin, the distillate from this operation is heated for about one hour on a
steam bath in order to drive out most of the excess
hydrogen chloride. The distillate is then fractionated under reduced pressure
(Note 3) in a
modified Claisen flask (p. 130). The
fractionating side arm should be 25 cm. in length. The fractions collected under 10 mm. are: to 55°, 55–57°, 57–65°, 65–85°, 85–105°, residue.
Before a further fractionation is carried out, the residue is discarded; the portion boiling at 85–105°, consisting chiefly of unchanged trimethylene glycol, is set aside for use in a later preparation; the low-boiling portion up to 55°, consisting mainly of water and hydrogen chloride with some trimethylene chloride (Note 4) and trimethylene chlorohydrin, is neutralized carefully with powdered sodium carbonate. Two layers form, and the upper containing the chlorohydrin is separated, dried over anhydrous potassium carbonate, and again replaced as the portion boiling up to 55°. Another complete fractional distillation, carried out in the usual way, is now made except that the highest fraction boils at 65–85°/10 mm.
The material boiling above 65°/10 mm. is chiefly trimethylene glycol and is used in a succeeding experiment. The final yield of trimethylene chlorohydrin (Note 5) boiling at 60–64°/10 mm. is 835–1000 g. from 1800 g. of trimethylene glycol (50–60 per cent of the theoretical amount), and 400–450 g. of trimethylene glycol is recovered.
2. Notes
1.
Hydrogen Chloride.—The
hydrogen chloride may be generated by any method desired. Since a large quantity of gas is required, the first procedure described on
p. 293 is rather expensive. A more satisfactory arrangement is to half fill a
12-l. flask with a paste of salt and concentrated
hydrochloric acid and run into this commercial
sulfuric acid. The gas is dried by a
single wash bottle of
sulfuric acid.
If sulfuric and hydrochloric acids are used, then, for the conversion of 1800 g. of trimethylene glycol, a 20-l. bottle half-filled with concentrated sulfuric acid is treated with concentrated hydrochloric acid introduced through a tube reaching to the bottom. The hydrochloric acid is added at the rate of 30–40 drops per minute. Two charges of sulfuric acid are needed and a total of about 24 kg. of hydrochloric acid.
2.
The yield of chlorohydrin is largely determined by the rate at which the reaction is carried out. A very rapid stream of
hydrogen chloride is absolutely essential for obtaining the yields mentioned. Moreover, it is very important to keep as small an amount of glycol as possible in the reaction flask. If larger amounts of glycol are present at any one time, the yield of product is lowered and considerable tar is produced.
3.
Trimethylene chlorohydrin cannot be distilled under atmospheric pressure without some decomposition. The fractionation can be carried out at ordinary pressures when the fractions collected are up to 125°, 125–158°, 158–164°, 164–190°, 190–210° and residue. This procedure is less desirable as some
hydrogen chloride is evolved and the product turns dark on standing.
4.
The portion boiling up to 55°/10 mm., obtained after the second fractionation, was washed with concentrated
sulfuric acid, then water, and finally dried and distilled. A certain amount of
trimethylene chloride was sometimes obtained, boiling at
115–120° and amounting to about 30 per cent of the total fraction.
5.
The chlorohydrin contains a very small amount (less than 0.5 per cent) of water-insoluble material, which is probably
trimethylene chloride and
di-γ-chloropropyl ether.
3. Discussion
Trimethylene chlorohydrin can be prepared from
trimethylene glycol by the action of dry
hydrogen chloride under various conditions;
1 by the action of aqueous
hydrochloric acid;
2 and by the action of
sulfur chloride.
3 It can also be prepared from
γ-chloropropyl acetate and
methyl alcoholic hydrochloric acid.
4
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
sulfuric and hydrochloric acids
methyl alcoholic hydrochloric acid
potassium carbonate (584-08-7)
sulfuric acid (7664-93-9)
hydrogen chloride,
hydrochloric acid (7647-01-0)
sodium carbonate (497-19-8)
trimethylene glycol (504-63-2)
Trimethylene chlorohydrin,
1-Propanol, 3-chloro- (627-30-5)
sulfur chloride
trimethylene chloride (142-28-9)
di-γ-chloropropyl ether (629-36-7)
γ-Chloropropyl acetate (628-09-1)
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