Org. Synth. 1950, 30, 24
[Cyclopentanol, 2-chloro-, trans-]
Submitted by Hugh B. Donahoe and Calvin A. Vanderwerf1
Checked by Arthur C. Cope and Elbert C. Herrick.
A mixture of 150 g. (2.5 moles) of urea
, 125 g. (1.25 moles) of reprecipitated calcium carbonate
, and 150 ml. of water in a 2-l. three-necked flask is tared and cooled in an ice-salt bath
. The flask is equipped with a thermometer
which extends into the reaction mixture, a gas inlet tube
, an outlet tube leading to a gas-absorption trap
and a slip- or mercury-sealed mechanical stirrer
which will disperse chlorine
gas below the surface of the liquid (Note 1)
A rapid stream of chlorine gas is bubbled into the mixture at 0–15° with vigorous stirring until an increase in weight of about 95 g. has occurred (30–40 minutes) (Note 2). A 250-ml. portion of water at room temperature is added to the suspension, which is then filtered by suction through rather porous filter paper on a 16-cm. Büchner funnel. The filtrate is removed and cooled in an ice bath, and the filter cake is washed on the funnel with a 250-ml. portion of water at room temperature. The filtrate is poured back in the funnel and sucked through the filter cake repeatedly until no more solid appears to dissolve, and then is combined with the original filtrate (Note 3).
The cold filtrates (solutions of monochlorourea) are transferred to a 3-l. two-necked flask immersed in an ice-salt bath. The flask is equipped with a slip- or mercury-sealed mechanical stirrer and an efficient reflux condenser. To the flask are added 500 g. of ice, 100 ml. of glacial acetic acid, and 136 g. (2.0 moles) of cyclopentene (or 1.43 times the weight increase in grams during introduction of the chlorine) (Note 4). Mechanical stirring is begun and is continued while the flask is kept packed in ice until the cyclopentene (the top layer) disappears and a heavy oil settles to the bottom (Note 5).
The solution is saturated with sodium chloride and distilled with steam until all the 2-chlorocyclopentanol is collected, which requires distillation of a volume of about 2 l. The distillate is saturated with sodium chloride, the oily layer separated, and the aqueous layer extracted four times with 300-ml. portions of ether. The ether extracts are added to the oil, and the solution is washed with a saturated sodium chloride solution and dried over anhydrous sodium sulfate. The ether is removed by distillation, and the product is distilled under reduced pressure through a total condensation, variable take-off, 15 by 1.5 cm. column packed with glass helices. A trap cooled with Dry Ice is placed in the vacuum line between the column and the pump. Low-boiling fractions, b.p. 43–81°/15 mm., amount to 19–40 g. (Note 6). The trans-2-chlorocyclopentanol is collected at 81–82°/15 mm. in a yield of 126–135 g. (52–56%); nD25 1.4770 (Note 7).
Rapid absorption of chlorine
depends on efficient stirring and dispersal of the gas through the liquid phase. A stirrer which disperses the gas through the solution by vigorous agitation may be used (p.891)
or the gas may be introduced through the stirrer.3
The actual weight of chlorine
absorbed is equal to the sum of the weight increase noted plus the weight of carbon dioxide
formed minus the relatively small weight of carbon dioxide
that remains dissolved in the reaction mixture.
The combined filtrates may be titrated with 1N sodium thiosulfate
solution to determine the yield of monochlorourea
This preparation of monochlorourea
is a modification of procedures previously described.4,5
Best yields result when an excess of cyclopentene
is used, as specified. The weight increase should be roughly 95 g., and the amount of cyclopentene
should be varied proportionately by using 1.43 times the weight increase in grams.
The stirring time is about 12–15 hours. It is advantageous to allow the ice to melt and the reaction mixture to come to room temperature during the last 2–3 hours.
The fractions boiling at 43–48°/15 mm. and 48–81°/15 mm. contain a mixture of 1,2-dichlorocyclopentane
and cis- and trans-2-chlorocyclopentanol
The yield is based on the weight of cyclopentene
, although this reagent is used in slight excess.
has been prepared by the reaction of dry hydrogen chloride8
or thionyl chloride9
, and by the addition of hypochlorous acid
Chemical Abstracts Nomenclature (Collective Index Number);
hydrogen chloride (7647-01-0)
acetic acid (64-19-7)
thionyl chloride (7719-09-7)
sodium chloride (7647-14-5)
sodium sulfate (7757-82-6)
sodium thiosulfate (7772-98-7)
carbon dioxide (124-38-9)
calcium carbonate (471-34-1)
hypochlorous acid (7790-92-3)
Cyclopentanol, 2-chloro-, trans-,
cis- and trans-2-chlorocyclopentanol
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