A
2-L, three-necked flask is thoroughly flamed while being flushed with
argon and is then fitted with three
rubber septa. Anhydrous
titanium trichloride (63.16 g, 0.409 mol) (Note
1) and (Note
2) is added to the weighed flask in an
argon-filled glove bag. The flask is reweighed, and one of the rubber septa is replaced with a dry (12 hr at 120°C)
reflux condenser through which a stream of
argon is flowing (Note
3). The flask is fitted with a
mechanical stirrer equipped with a
glass shaft and
Teflon paddle (Note
4). Into the flask is syringed
600 mL of 1,2-dimethoxyethane (Note
5), and the remaining rubber septum is exchanged for a
glass stopper.
Lithium (8.52 g, 1.23 mol) (Note
6) is etched to brilliance in
methanol, quickly washed in
petroleum ether (Note
7), and cut into small pieces directly into the stirred suspension. The mixture is heated at reflux for 1 hr by an
oil bath that is then removed (Note
8). Immediately after the solvent has ceased to reflux,
2-adamantanone (15.36 g, 0.102 mol) (Note
1) is added in one portion, and the mixture is heated at reflux for 18 hr.
Stirring is maintained as the mixture is allowed to cool to room temperature, and
600 mL of petroleum ether (Note 7) is added in 100-mL portions at 5-min intervals (Note
9). The stirrer is disconnected from its
motor, and the solution is poured into a
sintered-glass funnel containing 50 g of Florisil (approximately 7 cm in depth) (Note
1). The black material remaining in the reaction vessel is washed with eight
50-mL portions of petroleum ether, which are poured into the same pad of Florisil (Note
10) and (Note
11). The filter pad is then washed with
400 mL of petroleum ether. Removal of the solvent from the combined filtrates by means of a
rotary evaporator followed by high vacuum (0.05 mm) gives
12–13 g of a white crystalline solid. This crude product is dissolved in
3.5 L of hot methanol (Note
1), and the volume is reduced to 2 L by boiling. The solution is allowed to slowly cool to room temperature. The colorless needles are vacuum filtered through sintered glass (medium frit) and washed with
50 mL of ice-cold methanol. The crystals are dried under vacuum (0.05 mm Hg) to give
10.3–10.4 g (
75–76%) of
adamantylideneadamantane, mp
184–186°C;
1H NMR (CDCl
3) δ: 1.5–2.1 (br m, 24 H) 2.7–3.1 (br m, 4 H). Concentration of the mother liquor to 350 mL and crystallization as described above yields an additional
1.2–1.5 g (
9-11%) of product, mp
182–184°C (Note
12).