A solution of
63 g. (0.226 mole) of pure triphenylchloromethane (Note
1) in
1.5 l. of pure anhydrous ether is prepared in a
2-l. bottle provided with a tight ground-glass stopper, and
1150 g. of freshly prepared 1 per cent sodium amalgam (0.5 gram atom of sodium) is added (Note
2). The stopper is greased with a small amount of Lubriseal and the bottle is stoppered tightly. The bottle is clamped firmly in a
mechanical shaker and shaken vigorously. The reaction is strongly exothermic, and the bottle should be cooled with wet towels during the shaking operation. A persistent blood-red color develops rapidly, generally within ten minutes. After shaking for three hours
the bottle is cooled to room temperature, removed from the shaker, and allowed to stand undisturbed until the
sodium chloride has settled (Note
3).
The
ether solution of
triphenylmethylsodium is separated from the
sodium chloride and amalgan by the following procedure. The stopper of the reaction bottle is removed and replaced immediately by a
closely fitting two-holed cork carrying a short glass tube that protrudes about 1 cm. into the bottle, and a long glass tube bent into an inverted U-shape. The short tube is connected through a drying train to a cylinder of
nitrogen. One arm of the U-tube reaches to within about 4 cm. of the bottom of the bottle, and the other end extends just below the bottom of a two-holed cork that is fitted tightly into a
2-l. Erlenmeyer flask. The flask is filled with
nitrogen and serves as
receiver for the decanted solution. The cork of the Erlenmeyer flask is provided with a
short-stemmed separatory funnel which serves to release
nitrogen during the decantation and may be used subsequently to introduce reactants (Note
4). The corks are sealed by a coating of paraffin-wax. The stopcock of the
dropping funnel is opened slightly, and the
ether solution of
triphenylmethylsodium is forced slowly and steadily into the nitrogen-filled flask by means of a small pressure of
nitrogen from the cylinder. With proper adjustment of the height of the glass tube above the surface of the
sodium chloride and amalgam, it is possible to remove all but
50 to 75 cc. of the ether solution.
If a good grade of
triphenylchloromethane and freshly prepared amalgam are used the yield of
triphenylmethylsodium is almost quantitative. The solution may be analyzed approximately, as follows: A 50-cc. aliquot portion is allowed to flow into 25 cc. of water in a separatory funnel. The aqueous layer is drawn off and the
ether solution washed with three 25-cc. portions of water. The aqueous solutions are combined, boiled to expel
ether, and titrated with
0.2 N sulfuric acid,
methyl red being used as indicator.