Submitted by C. S. Marvel and P. K. Porter.
Checked by H. T. Clarke and E. R. Taylor.
1. Procedure
In a
2-l. round-bottomed flask fitted with a
stopper carrying a
reflux condenser and a
glass tube reaching nearly to the bottom of the flask are placed
350 g. (438 cc., 10.9 moles) of methyl alcohol and
900 g. of technical formalin containing 252 g. (8.4 moles) of formaldehyde (Note
1).
A rapid stream of
hydrogen chloride (Note
2) is run into the mixture, which is cooled with running water. In about two hours a layer of
chloromethyl ether begins to appear. The stream of
hydrogen chloride is continued for two or three hours longer until the solution is saturated. The layer of
chloromethyl ether is then separated. The water layer is saturated with
calcium chloride (Note
3), and more ether separates. This is added to the main portion, which is then dried over
calcium chloride and fractionally distilled. The yield of product boiling at
55–60° is
580–600 g. (
86–89 per cent of the theoretical amount based on the
formaldehyde).
2. Notes
1. The following table, showing the relation between the density of
formalin solutions and their
formaldehyde content, has been found useful. It is copied from Beilstein's "Handbuch der organischen Chemie," 4th Ed., Julius Springer, Berlin, 1918, Vol. I,
p. 561.
|
d148 |
g. CH2O in 100 cc. |
g. CH2O in 100 g. |
|
1.0054 |
2.24 |
2.23 |
1.0126 |
4.66 |
4.60 |
1.0311 |
11.08 |
10.74 |
1.0410 |
14.15 |
13.59 |
1.0568 |
19.89 |
18.82 |
1.0719 |
25.44 |
23.73 |
1.0853 |
30.17 |
27.80 |
1.1057 |
37.72 |
34.11 |
1.1158 |
41.87 |
37.53 |
|
The values in this table are affected by the presence of
methyl alcohol in the
formalin solution; since it has been pointed out that technical
formalin contains 8–10 per cent of
methyl alcohol, the table is not satisfactory for determining the
formaldehyde content of
technical formalin solutions. For example, a solution containing 37 per cent of
formaldehyde and 10 per cent of
methyl alcohol would have a density of 1.09 and correspond to 28 per cent of
formaldehyde in pure water. In view of this the percentage yield in the preparation described above should probably be
64–66 instead of
86–89 (Norman D. Scott, private communication).
3. Discussion
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