Organic Syntheses, CV 4, 101
Submitted by Saul R. Buc
1
Checked by Charles C. Price, Frederick V. Brutcher, and Jerome Cohen.
1. Procedure
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,
thermometer, 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. (
76–81%) of product sufficiently pure for many purposes is obtained. On distillation there is obtained
330–350 g. (
72–76%) of
bischloromethyl ether, boiling at
100–104°. Approximately
95% boils at
101–101.5°,
n25D 1.4420 (Note
3).
2. Notes
1. Local overheating must be carefully avoided during the alkaline washing, since it may result in vigorous decomposition.
2. The washing and drying are carried out as rapidly as possible to avoid hydrolysis of the product.
3. The submitter reports that operation of this procedure on a scale of
72 moles of paraformaldehyde gave a crude yield of
3601 g. (
87%) and a distilled yield of
3519 g. (
85%).
3. Discussion
This preparation is referenced from:
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