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Organic syntheses - Roger A.

Roger A. Organic syntheses - Chapman, 1936. - 110 p.
Download (direct link): organicsintencis1936.pdf
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fraction is collected up to 75V50 mm., and the residue (about 160-180
cc.), which contains a large percentage of dichlorohydrin, is returned to
the original reaction flask, together with 150 cc. of water. This
30
EPICHLOROHYDRIN AND EPIBROMOHYDRIN 31
material is distilled once under reduced pressure as described above, and
the lower layer of the distillate is combined with the main fraction of
epichlorohydrin. The crude product is distilled at ordinary pressure
until the temperature of the vapor reaches 1150; at this point the
distillation is stopped and the water layer removed from the distillate.
The lower layer of the distillate is dried over anhydrous sodium sulfate
and returned to the distilling flask. After a small fore-run, the
epichlorohydrin distils at 115-1170. The yield is 650-700 g. (67-72 per
cent of the theoretical amount).
(B) Epibromohydrin.-In a 5-I. round-bottomed flask, 2140 g. (1000
cc., 9.8 moles) of glycerol ct^-dibromohydrin (Org. Syn.
14, 42) is suspended in 1.5 1. of water, and 400 g. of technical,
powdered calcium hydroxide (88 per cent) is added gradually, with
shaking, in the course of about fifteen minutes. A further quantity of
400 g. of calcium hydroxide (total, 10 moles) is added at once, and the
epibromohydrin is distilled at reduced pressure in the manner described
for epichlorohydrin (Note 2). The combined lower layers from two such
distillations (about 750 cc.) are dried over anhydrous sodium sulfate and
fractionated at atmospheric or reduced pressure. The yield of
epibromohydrin, b.p. 134-136 or 6i-62/5o mm., is 1130-1200 g. (84-89
per cent of the theoretical amount).
2. Notes
1. The prescribed amount of water should be used; more water
causes frothing. The reaction is not exothermic.
2. Epichlorohydrin boils at ci-32/? mm., epibromohydrin at 61
62/5o mm. Both these liquids are quite volatile with water vapor under
reduced pressure.
3. The volume of the epichlorohydrin layer obtained in the
successive distillations is roughly: (1) 500 cc., (2) 200 cc., (3) 20 cc.
3. Methods of Preparation
Epichlorohydrin1 and epibromohydrin 2 have been prepared by treatment
of glycerol dichloro- and dibromohydrins with
32
ORGANIC SYNTHESES
alkalies in various ways. The procedures described here represent a
laboratory application of Griesheim's method.3
1 Org. Syn. Coll. Vol. I, 229.
* Berthelot and Luca, Ann. chim. [3] 48, 306, 311 (1856); Reboul,
ibid. [3] 60, 32 (i860).
3 Griesheim, Ger. pat. 246,242 [Frdl. 10, 22 (1910-1912)]; Braun, J.
Am. Chem. Soc. 64, 1248 (1932).
XI
ETHYL PHENYLMALONATE
(CaHiONa)
NaIaNIaNIaNaIa + (NIaNaI^a-------------->
C6H5CH(C02C2H5)C0C02C2H5 + C2H6OH
(heat)
NaIaNUNIaNaAANINIaNaIa ------------->
NaI5NI(N02N2I5)2 + ni
Submitted by P. A. Levene and G. M. Meyer.
Checked by L. F. Fieser and N. H. Fisher.
1. Procedure
In a 2-1. three-necked flask fitted with a mercury-sealed stirrer,
reflux condenser, and dropping funnel is placed 500 cc. of absolute ethyl
alcohol (Note 1), and 23 g. (1 gram atom) of cleanly cut sodium is added
in portions. When the sodium has dissolved the solution is cooled to 6o,
and 146 g. (1 mole) of ethyl oxalate (Org. Syn. Coll. Vol. 1, 256) (Note
2) is added in a rapid stream through the funnel with vigorous stirring.
This is washed down with a small quantity of absolute alcohol, and is
followed immediately by the addition of 175 g. (1.06 moles) of ethyl
phenylace-tate (Org. Syn. Coll. Vol. 1, 265) (Note 2). Stirring is
discontinued at once, the reaction flask is lowered from the stirrer, and
a 2-1. beaker is made ready. Within four to six minutes after the ethyl
phenylacetate has been added crystallization sets in. The contents of the
flask are transferred immediately to the beaker at the first sign of
crystallization, which is nearly instantaneous.
The nearly solid paste of the sodium derivative is allowed to cool to
room temperature and then stirred thoroughly with 800 cc. of dry ether.
The solid is collected by suction and washed repeatedly with dry ether.
The phenyloxaloacetic ester is liberated from the sodium salt with dilute
sulfuric acid (29 cc.
33
34
ORGANIC SYNTHESES
of concentrated sulfuric acid in 500 cc. of water). The nearly colorless
oil is separated, and the aqueous layer is extracted with three 100-cc.
portions of ether, which are combined with the oil. The ethereal solution
is dried over anhydrous sodium sulfate, and the ether is distilled off.
The residual oil, contained in a modified Claisen flask having a
fractionating side arm, is heated under a pressure of about 15 mm. in a
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