Checked by R. S. Schreiber and Burris D. Tiffany.
1. Procedure
The apparatus used is shown in
f.htmig. 6 (Note
1). A solution of
sodium ethoxide prepared by dissolving 2.5 g. (0.11 g. atom) of clean sodium in 230 g. (292 ml., 5 moles) of absolute ethanol under anhydrous conditions is added to the
reaction tube C. Tube
C thus charged is weighed and placed in position with the
gas inlet tube, fitted with fritted-glass dispersion cylinder D, extending nearly to the bottom. Several inches of
ethanol is placed in tube
G, which serves as a flow indicator. The traps
A and
F are provided to protect against suck-back if the gas flow is interrupted. The seal at
B is a sleeve of rubber tubing. Any
efficient reflux condenser E is satisfactory.
Fig. 6.
Chlorotrifluoroethylene (Note
2) is introduced at such a rate, controlled by the needle valve, that it is essentially all absorbed in the reaction tube
C, as indicated by the escape of little or no gas through tube
G. At this rate, 233 g. (2 moles) (Note
3) is absorbed in 2–2.5 hours, during which the temperature rises to the point of reflux (Note
4).
2. Notes
1. The reaction tube
C may be of any convenient size. The tube used by the submitter was 300 by 55 mm., fitted with a 55/35 standard taper ground-glass joint. The checkers used a
500-ml. calibrated dropping funnel which was convenient for following the increase in volume during the absorption of the
chlorotrifluoroethylene. For safety, a
heavy grease such as Cello-Grease was used in the stopcock.
2. The
chlorotrifluoroethylene used was inhibited polymerization grade, supplied by the Kinetic Chemicals Division, Organic Chemicals Department, E. I. du Pont de Nemours and Company, Wilmington, Delaware.
3. The amount of
chlorotrifluoroethylene absorbed is determined by weighing the reaction tube
C and contents. A convenient alterntive is to note the increase in volume of the reaction mixture, which in this case amounts to 165 ml.
4. The rate of absorption is slow at first but increases as the temperature rises.
3. Discussion
Appendix
Compounds Referenced (Chemical Abstracts Registry Number)
ethanol (64-17-5)
calcium chloride (10043-52-4)
sodium (13966-32-0)
sodium ethoxide (141-52-6)
chlorotrifluoroethyl ethyl ether,
2-Chloro-1,1,2-trifluoroethyl ethyl ether,
Ether, 2-chloro-1,1,2-trifluoroethyl ethyl (310-71-4)
Chlorotrifluoroethylene,
1-chloro-1,2,2-trifluoroethylene (79-38-9)
ethyl chlorofluoroacetate (401-56-9)
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