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Organic Synthess - McKusick B.C.

McKusick B.C., Boekelheide V., Emmons W.D. Organic Synthess - New York, 1963. - 134 p.
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(b.p. 60-80°) gives 16—17 g. (75-80%) of 9-chloroanthracene as yellow needles, m.p. 104-106°.
2. Notes
1. Anthracene, B. D. H. (blue fluorescence), was used. Traces of ethylene glycol, glycerol, ethanol, or water considerably retard the reaction and lead to unsatisfactory results.
2. Anhydrous cupric chloride is dried in an oven at 110-120° for several hours and stored in a desiccator or over phosphorus pentoxide before use.
3. Chlorobenzene or jym-tetrachlorethane may be used instead of carbon tetrachloride as solvent, in which case the reaction is complete as soon as the mixture has reached reflux. The product is liable to be contaminated by a small amount of 9,10-dichloro-anthracene.
4. Merck alumina or Spence Type H alumina was used.
5. The 9-chloroanthracene at this stage usually contains a small amount of unreacted anthracene.
3. Methods of Preparation
9-Chloroanthracene has been prepared by the action of chlorine,2 teri-butyl hypochlorite,8 l,3-dichloro-5,5-dimethylhy-dantoin,4 or phosphorus pentachloride * on anthracene.
4. Merits of the Preparation
The present method is a one-step synthesis giving a high yield of 9-chloroanthracene from readily available starting materials.
It is thought that the chlorination proceeds through a тг-com- „ plex between cupric chloride and anthracene, and that this complex then undergoes homolytic dissociation.* Hence aromatic rings subject to attack by chlorine atoms can be chlorinated in this way. Thus one can convert pyrene to 1-chloropyrene (90% yield), but phenanthrene is not chlorinated. Analogous procedures using cupric bromide lead to 9-bromoanthracene (99% yield) and 1-bromopyrene (94% yield).7
• Chemistry Department, Royal College of Science and Technology, Glasgow, Scotland.
• У. Nagaki and M. Tanabe, KSgyS Kagaku Zasski, 60, 294 (1957) [C. A., 68, 8087 (1959)].
• J. W. Engelsma, E. Farenhorst, and E. C. Kooyman, Rec. Trav. С him., 73, 884 (1954).
4 О. O. Orazi, J. F. Salellas, М. E. Fondovila, R. A. Corral, N. М. I. Mercere, and E. C. Rakunas de Alvarez, Anales Asoc. Quim. Arg., 40, 61 (1952) [C. A., 47, 3244 (1953)].
• В. M. Mikhailov and M. Sh. Promyslov, J. Gen. Chem. (USSR), 20,338 (1950) [English Language Edition, Consultants Bureau, p. 359].
• D. C. Nonhebel, J. Chem. Soc., 1963,1216.
7 D. C. Nonhebel, Proc. Chem. Soc., 1961, 307.
l-CHLORO-l,4,4-TRIFLUOROBUTADIENE (Butadiene, 1-chloro-l ,4,4-trifluoro-)
-OCOCH3 Heat
Submitted by R. E. Putnam, В. C. Anderson, and W. H. Sharkey.1 Checked by R. D. Bixkenmeyek, M. A. Rebenstort, and F. Kagan.’
1. Procedure
A. 2-Chloro-2,3,3-trifluorocyclobutyl acetate (Note 1). A mixture of 1.0 g. of hydroquinone, 3 drops of a terpene inhibitor (Note 2), and 140 g. (1.63 moles) of inhibited redistilled vinyl acetate (Note 3) is placed in a 400-ml. high-pressure shaker tube lined with ,stainless steel (Note 4). The shaker tube is dosed,
cooled in a mixture of solid carbon dioxide and acetone, evacuated, and charged with 47 g. (0.40 mole) of chlorotrifluoro-ethylene (Note 5). The shaker tube is heated with agitation to 215° in a period of about 1 hour and is then heated at 215° for 3 hours. The shaker tube is cooled to room temperature and is bled slowly to remove excess chlorotrifluoroethylene. The black, viscous reaction mixture (Note 6) is transferred to a distillation flask and heated on a steam bath. After a fore-run of d^chloro-hexafluorocyclobutane and vinyl acetate is collected at atmospheric pressure, a receiver cooled in solid carbon dioxide and acetone is attached, and crude 2-chloro-2,3,3-trifluorocyclobutyl acetate is rapidly distilled by gradually reducing the pressure to about 10 mm. (Note 7). Redistillation through a 30-cm. column packed with glass helices provides 22-30 g. (27-37%) (Note 8) of the acetate, b.p. 60-65°/!00 mm., 1.3916-1.3921.
B. l-Chloro-l,4,4-triJluorobutadiene. The apparatus is similar to that described in a previous volume.12 It consists of a “Vycor” glass reaction tube, 60 cm. long by 25 mm. outside diameter, mounted vertically in an electric furnace about 35 cm. long (Note 9). Attached to the top of the tube is a graduated dropping funnel. A thermocouple well extending to the center of the heated section is inserted through the bottom of the tube. The heated section of the tube is packed with quartz tubing (8 mm. outside diameter), cut into 0.5-cm. lengths, and held in place by indentations in the tube. Ten centimeters from the bottom of the tube is a side arm leading successively to two traps cooled with solid carbon dioxide and acetone, an inlet tube for nitrogen, a manometer, and a vacuum pump.
The system is evacuated to a pressure of 5-10 mm., and the tube is heated to 700°, measured at the center of the heated zone.
2-Chloro-2,3,3-trifluorocyclobutyl acetate is admitted at the rate of 10-20 g. per hour. From 70 g. (0.35 mole) of the cyclobutyl acetate there is obtained 62-68 g. of mixed solid and liquid condensate (Note 10). Fractionation through a 30-cm. column packed with glass helices affords 30-35 g. (60-70%) of 1-chloro-
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