Aluminum magnesium residue, extraction

To a flame-dried, three-neck, 1-1 flask were added, in order, p-xylene (107 g, 1.0 mol), phosphorus trichloride (412 g, 3.0 mol), and anhydrous aluminum chloride (160 g, 1.2 mol). The reaction mixture was slowly heated to reflux with stirring. After 2.5 h at reflux, the reaction was allowed to cool to room temperature and the volatile components distilled at reduced pressure. The residual oil was slowly added to cold water (1 1) with stirring, and a white solid formed. The solid was removed by filtration, washed with water, and air dried. The solid was suspended in water (1 1) to which was added 50% sodium hydroxide solution (90 ml) to cause dissolution. The solution was saturated with carbon dioxide and filtered through Celite . The basic solution was washed with methylene chloride (200 ml) and acidified with concentrated hydrochloric acid (200 ml). The white solid that separated was isolated by extraction with methylene chloride (3 x 250 ml). The extracts were dried over magnesium sulfate, filtered, and evaporated under reduced pressure to give the pure 2,5-dimethylbenzenephosphinic acid (99 g, 60%) as an oil, which slowly crystallized to a solid of mp 77-79°C. 

The hot cyclohexane layer is carefully decanted, and the aluminum bromide layer is extracted with five 200-ml. portions of hot cyclohexane. Ether (400 ml.) is added to the cooled cyclohexane extracts (Note 11), and the combined solvent fractions are washed with two 100-ml. portions of water and dried over anhydrous magnesium sulfate. Evaporation of the solvent leaves a semi-solid residue that is partially dissolved in about 100 ml. of pentane. The undissolved white solid, diamantane, is collected by suction filtration. Additional diamantane is obtained by concentrating the pentane solution to a small volume and collecting the solid that precipitates. The total amount of diamantane obtained, after drying, is 60-62 g. (60-62%), m.p. 240-241° (closed tube) (Note 12). This product is sufficiently pure for most purposes, but it may be purified further by recrystallization from pentane to give white crystals, m.p. 244.0-245.4°. 

Diphcnyl-l,2,5-telluradiazole1 0.7 g (2.45 mmol) of 3,4-diphenyl-1,2,5-selenadiazole are dissolved in 140 m/ of diethyl ether (previously refluxed over sodium wire and then treated with lithium aluminum hydride under nitrogen) and added dropwise to a stirred solution of 5.9 mmol of ethyl magnesium bromide in diethyl ether at 20 under nitrogen. The mixture is stirred at 20° for 2 h and then cooled to — 60°. 0.29 g (2.94 mmol) of 100% sulfuric acid in diethyl ether arc added dropwise followed by 0.86 g (3.19 mmol) of tellurium tetrachloride in diethyl ether and, after several minutes, 4.9 g (49 mmol) of tricthylamine. The mixture is stirred overnight at 20° and filtered. The solid is extracted in a Soxhlct extractor with 200 ml of boiling dichloromethane. The extract is evaporated under vacuum, the residue is washed with 60 ml of water followed by 20 ml of acetone, dried under vacuum, and recrystallized from dimethylformamidc yield 0.65 g (79%) m.p. 272° (dec.). 

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