Submitted by Winston Wayne and Homer Adkins.
Checked by Nathan L. Drake, Wm. H. Souder, Jr., and Ralph Mozingo.
1. Procedure
In a
2-l. round-bottomed flask, bearing a
reflux condenser protected by a
calcium chloride tube, are placed
64 g. (2.37 gram atoms) of aluminum shavings,
200 g. (254 ml., 2.7 moles) of dry tert-butyl alcohol, and
5–10 g. of aluminum tert-butoxide (Note
1). After the mixture is heated to boiling on a
steam bath, approximately
0.4 g. of mercuric chloride is added followed by vigorous shaking (Note
2). As the heating is continued the color of the reaction mixture gradually changes from clear to milky to black, and
hydrogen is evolved. When the mixture has become black, the heating is interrupted.
After the reaction has been allowed to proceed for an hour without heating, an additional
244 g. (309 ml., 3.3 moles) of dry tert-butyl alcohol (total quantity, 6 moles) and
200 ml. of dry benzene are added. The reaction will again set in upon gentle heating and will continue vigorously without further heating. After about 2 hours the reaction subsides and the mixture is refluxed for about 10 hours.
The
benzene and unchanged
tert-butyl alcohol are removed by distillation from the steam bath, the final traces being removed under 10–30 mm. pressure.
A liter of dry ether is added, and the solid
aluminum tert-butoxide is dissolved by refluxing for a short period. After cooling,
35 ml. of undried ether is added, followed immediately by vigorous shaking (Note
3). After standing for 2 hours the solution is centrifuged for 30 minutes to remove unused
aluminum,
aluminum hydroxide, and
mercury (Note
4).
The solvent is removed by distillation from the steam bath, the final traces under 10–30 mm. pressure. The flask is allowed to cool with a calcium chloride tube attached, and the product is crushed with a spatula and transferred to bottles sealed against moisture. The yield is 394–418 g. (80–85%) of a white or slightly gray solid.
2. Notes
2. The use of larger amounts of
mercuric chloride increases the difficulty of getting the final product free from color. This difficulty may be avoided by previously amalgamating the
aluminum.
3,4 The mixture is shaken to distribute the
mercuric chloride and thus aid in an even amalgamation of the
aluminum.
3. The small amount of water introduced with the undried
ether forms
aluminum hydroxide which aids in the precipitation of the black suspended material. Shaking is essential to obtain the hydroxide formation throughout the solution.
4. The centrifuging may be carried out in
250-ml. stoppered bottles at 2000 r.p.m. After centrifuging, the solution should be colorless or light tan. If it is still dark in color another
25-ml. portion of undried ether should be added and the centrifuging repeated.
3. Discussion
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