Chromatographic alumina

Diisopropyi ketone (2,4-dimethyi-3-pentanone) [565-80-0] M 114.2, b 124 , d 0.801, n 1.400. Dried with CaS04, shaken with chromatographic alumina and fractionally distd from P2O5 under N2. 

Shaken with aq 5% Na2C03, dried with MgS04 and stored with chromatographic alumina to prevent peroxide formation. 

The organic layer is separated, evaporated on a steam bath, and the dark semicrystalline residue is distilled with steam to remove biphenyl. The contents of the steam-distillation flask are then extracted with ether (Note 3), and the ethereal layer is separated, dried over magnesium sulfate, and percolated through a short column of chromatographic alumina (Notes 4 and 5). Evaporation of the ethereal solution gives crude triphenylene which is sublimed at 175-180° and 0.1 mm. pressure. After rejection of an initial sublimate of impure biphenyl, the sublimed material forms nearly colorless crystals, m.p. 186-194° (Note 6). Yield 8-9 g. (53-59%). It may be further purified by recrystallization from a mixture of methylene chloride and pentane yielding colorless crystals, m.p. 199° (Note 7). 

This solution is then slowly passed through a chromatographic alumina column, 20 cm in length and 16 mm in diameter, containing 20 g of alumina (Prolabo ). 

A solution of 2-bromo-4-chloro-5-phenyl-2,3-dihydro-1-benzothiepin (1.02 g, 2.84 mmol) in THF (3 mL) was added in one portion to a solution of DBN (0.52 g, 4.2 mmol) in THF (3 mL) at rt. After stirring for 2h, the red mixture, containing some precipitate, was poured into 10% aq HC1 (20 mL) and the aqueous solution was extracted with CHCl, (2x15 mL). The combined extracts were washed with H20, dried (MgS04) and carefully concentrated in vacuo at subambient temperature. The yellow oil, which solidified on cooling, was chromatographed [alumina (Merck 71707,25 g), hexane] to give colorless crystals yield 0.58 g (76%) mp 87-88 °C. 

The nitro compound in Et2NH (70 mol equiv) was either heated under reflux with (EtO)2PMe (2- 5 mol equiv) under N2, or the mixture was heated in an autoclave at 57°C, until the reaction was complete as shown by GC analysis of the reaction mixture (4-7d). The excess Et2NH was removed under vacuum and the residue was chromatographed (alumina) to give the product which was further purified by distillation or crystallization. 

A solution of 5-methoxy-6//-l, 4-diazepine (0.386 g, 3.1 mmol) and benzoyl chloride (0.550 g, 3.9 mmol) in pyridine (5 mL) was kept for 2 d in a refrigerator and ice-water (15 mL) was then added. The mixture was extracted with CH2C12 and the extract was washed with H20. dried and concentrated under reduced pressure. The residue was chromatographed (alumina, benzene) to give the product yield 0.420 g (65%) oil. 

The amine 1 b (R = Me 6.0 g, 22 mmol) in THF (150 mL) was added over 30 min to a stirred suspension of LiA1H4 (3.0 g, 79 mmol) in THF (50 mL) and the mixture was heated under reflux for 4h. Excess reagent was destroyed by the careful addition of a little EtOH, followed by a little H20, and the mixture was filtered from a precipitate, which was washed with Et20. The combined filtrate and washings were dried and evaporated in vacuo. The residue was chromatographed (alumina, EtjO/hexane 7 3) to give the red product yield 0.97 g (21 %) mp 140 140.5 C. 

A solution of the dilithio compound 3. prepared from 2.5-dichloro-3,4-diiodothiophene (4.85 g, 12 mmol) and 1.6 M BuLi in hexane (15mL. 24 mmol), in Et20 (100 mL) was stirred under N2 at — 95 C and sulfur (0.77 g. 2 equiv) was added. The mixture was allowed to warm to — 20 C and was slowly treated with SC12 (1,236 g, 12 mmol). After 15 min, H20 (50 mL) was added, the organic layer was separated, dried and evaporated and the residue was chromatographed (alumina) to give the product as pale-yellow needles mp 126 C. (The yield was not reported.)... 

A mixture of PcSi(OH)2 (0.75 g, 1.3 mmol), chlorotrihexylsilane (5.0 mL), and anhyd pyridine (75 mL) was refluxed for 5 h. After the solution obtained had been allowed to cool, it was filtered and concentrated under vacuum. The resulting oil was mixed with pentane (10 mL) and the slurry formed was filtered. The solid was washed with pentane (10 mL) and acetone/H20, vacuum dried, and weighed (0.78 g). To recover additional product, the pentane filtrates were combined, concentrated, and filtered. The solid was washed and vacuum dried. The combined solids were chromatographed (alumina, toluene/hexane 1 2) yield 0.28 g (78%). 

Chromatographic alumina (400 g.) is treated with 500 ml. of ethyl acetate at room temperature. After 48 hours, the alumina is collected on a filter and washed first with 1 1. of distilled water and then with 1 1. of methanol. After drying in air, the alumina is activated by heating at 120° for 3 hours at 50-100 mm. 

The crude solid is purified by dissolving it in 50 ml. of petroleum ether (b.p. 40-60°) and introducing it on a short alumina column (IS g.j Brockmann Activity 1 or an equivalent chromatographic alumina). The column is then eluted with 300 ml. of a 1 9 mixture of ether-petroleum ether (b.p. 40-60°). Concentration of the eluate leaves a solid which is recrystallized from aqueous ethanol to give 1.4-1.6 g. (70-80%) of diphenyldiacetylene as large colorless needles, m.p. 87-88° (Note 10). 

Oxidation and Reduction.—A number of selective oxidation procedures have been reported. Trichloroacetaldehyde on dehydrated chromatographic alumina converts the diol (15) into the 3/3-hydroxy-17-ketone (68%)." Primary alcohols are reported to be less readily oxidized than secondary alcohols by this reagent. Similarly, bromine or chlorine with HMPA oxidizes secondary alcohols more readily than primary alcohols. Thus the diol (16) was converted into the ketol (17)... 

The complex cis-Mo(CO)2(dppe)2 [l,2-ethanediylbis(diphenylphosphine)] is prepared by the literature method.8 In a dry box, a quantity (427 mg, 0.450 mmol) of this complex is mixed with NOPF6 (162 mg, 0.923 mmol). The NO[PF6] must be freshly prepared or from a freshly opened bottle. Dichloromethane (6 mL) is added and the mixture is rapidly stirred for 10 to 15 min until the solid has completely dissolved giving a green solution. This is eluted through a 5-cm column (diameter, 7 mm) of chromatographic alumina with dichloromethane. The bright yellow eluate is concentrated to a few milliliters by a water pump. Methanol (lOmL) is added and the mixture is cooled in an ice bath giving canary yellow crystals. These are filtered, washed with methanol, and dried in vacuo. Yield 260 mg (52%). 

Ethylene glycol bis(B-aminoethylether)-V,V -tetraacetic acid (EGTA) [67-42-5] M 380.4, m >245 (dec). Dissolved in aq NaOH, pptd by addn of aq HCl, washed with water and dried at 100° in vacuo. ueous 5% Na2CO3, dried with MgSO4 and stored with chromatographic alumina to prevent peroxide formation. 

A modified Oppenauer oxidation, using activated neutral chromatographic alumina and chloral in CCI4 at room temperature, allows the oxidation of cyclobutanol in ... 

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