Organic Syntheses, Coll. Vol. 4, p.101 (1963); Vol. 36, p.1 (1956).
Caution! It has been reported that exposure to bischloromethyl ether
in low concentrations has caused severe irritation of the eyes and respiratory tract, and perhaps pulmonary edema.
Proper safeguards should be taken to prevent exposure to this material both during and after its preparation. It is recommended that all operations involving this compound be carried out in a good hood.
In a 1-l. three-necked flask
immersed in an ice bath
and provided with a stirrer
, and dropping funnel
are placed 168 ml. (200 g.) of concentrated (37–38%) hydrochloric acid (2 moles)
and 240 g. of paraformaldehyde (effectively 8 moles of formaldehyde)
. While the temperature is maintained below 10°, 452 ml. (6.9 moles) of chlorosulfonic acid
is added dropwise at such a rate that gaseous hydrogen chloride
is not lost from the mixture. This requires about 5.5 hours. The mixture is stirred for 4 hours in the melting ice bath and comes to room temperature. It may be allowed to stand overnight. The layers are separated, and the product (upper layer) is washed twice with ice water. Ice is added to the product, and 250 ml. of 40% sodium hydroxide
is then added to the mixture slowly with vigorous agitation until the aqueous phase is strongly alkaline (Note 1)
. The product is separated and dried rapidly over potassium carbonate
and then over potassium hydroxide
, keeping the product cold during drying (Note 2)
. After separation of the drying agent by filtration, 350–370 g.
) of product sufficiently pure for many purposes is obtained. On distillation there is obtained 330–350 g.
) of bischloromethyl ether
, boiling at 100–104°.
boils at 101–101.5°
1.4420 (Note 3)
Local overheating must be carefully avoided during the alkaline washing, since it may result in vigorous decomposition.
The washing and drying are carried out as rapidly as possible to avoid hydrolysis of the product.
The submitter reports that operation of this procedure on a scale of 72 moles of paraformaldehyde
gave a crude yield of 3601 g.
) and a distilled yield of 3519 g.
This preparation is referenced from:
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