Organic Syntheses, CV 2, 312
unsym.-HEPTACHLOROPROPANE
Submitted by Mark W. Farlow
Checked by Frank C. Whitmore and F. W. Breuer.
1. Procedure
In a
1-l. round-bottomed flask, equipped with a
reflux condenser carrying a
calcium chloride tube, are placed
166 g. (103 cc., 1 mole) of technical tetrachloroethylene,
300 g. (200 cc., 2.5 moles) of dry chloroform, and
27 g. (0.2 mole) of anhydrous aluminum chloride. The mixture is refluxed gently on the
steam bath for fifteen hours (Note
1), cooled to room temperature, and poured into a
1-l. separatory funnel half filled with crushed ice. The organic layer is washed several times with water and dried over
calcium chloride or soluble anhydrite. By fractionation at atmospheric pressure through an
efficient column,
160–165 g. of chloroform is recovered. Distillation of the
unsym.-heptachloropropane fraction at diminished pressure gives material boiling at
110–113°/10 mm., or
137–140°/32 mm., and melting at
29–30°. The yield is
250–266 g. (
88–93 per cent of the theoretical amount) (Note
2).
2. Notes
1. A small amount of
hydrogen chloride is evolved in the initial stages of the reaction.
2. According to Prins
1 the
heptachloropropane can be isolated easily by pouring the reaction mixture into water and removing the unreacted materials by steam distillation. The process is stopped when the product begins to distil, and on cooling the residue is obtained as a colorless solid of the correct melting point.
3. Discussion
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