Alumina neutral

The neutralized, alumina-free sodium chromate solution may be marketed as a solution of 40° Bh (specific gravity = 1.38), evaporated to dryness, or crystallized to give a technical grade of sodium chromate or sodium chromate tetrahydrate [1003-82-9] Na2Cr04 4H2O. If the fuel for the kilns contains sulfur, the product contains sodium sulfate as an impurity. This compound is isomorphous with sodium chromate and hence difficult to separate. High purity sodium chromate must be made from purified sodium dichromate. 

Endo 3a,4,S,6,7,7a-Hexahydro-4,7-methano-2-lndene-l-one (2). A solution ol octacaibonyidcobalt (1.0 g, 3 mmol) and bicycio [2 2.1) hepi-2-ene 1 (3.0 g, 32 mmol) in Isooctane (100 mL) was stirred first with acetylene and then under a mixture of 1.1 of acetylene and carbon monoxyde at 60-70°C until gas absorption ceased (total 1550 mL). The mixture was concentrated and the residue chromatographed on neutral alumina. Petroleum ether PhH (1 1) eluted acetylene hexacaibonyl dicobalt 70 mg, PhH CHCla (1.1) eluted a yellow oil which after distillation afforded 3 54 g of 2 (74%), bp 101-102°C (15 mm) Colorless crystals from pentane, mp32°C. 

Alumina was purchased from Macherey, Nagel and Co., Diiren (FRG). The checkers employed 650 g of neutral alumina (Fisher, adsorption grade, 80-200 mesh) packed in a 40-cm high column. Yellow impurities remained on the column, while the blue azulene came off with the hexane solvent front. 

Benzeneazodiphenylamine (4-phenylazodiphenylamine) [28110-26-1] M 273.3, m 82, pK 1.52. Purified by chromatography on neutral alumina using anhydrous C6H6 with 1% anhydrous MeOH. The major component, which gave a stationary band, was cut out and eluted with EtOH or MeOH. [Hogfeldt and Bigeleisen J Am Chem Soc 82 15 I960.] Crystd from pet ether or EtOH. See Sudan I. 

Biphenylcarbonyl chloride [14002-51-8] M 216.7, m 114-115 . Dissolve in a large volume of pet ether (10 x, b 50-70 ), filter through a short column of neutral alumina, evaporate to dryness in vacuo and recryst from pet ether (b 60-80 ). LACHRYMATORY. 

Repeated chromatography on neutral alumina yields minor quantities of solid samples of C76, Cg4, C90 and C94 believed to be higher fullerenes. A stable oxide C70O has been identified. Chromatographic procedures for the separation of these compounds are reported. [Science 2S2 548 7997.]... 

Styrene is difficult to purify and keep pure. Usually contains added inhibitors (such as a trace of hydroquinone). Washed with aqueous NaOH to remove inhibitors (e.g. rert-butanol), then with water, dried for several hours with MgS04 and distd at 25° under reduced pressure in the presence of an inhibitor (such as 0.005% p-tert-butylcatechol). It can be stored at -78°. It can also be stored and kept anhydrous with Linde type 5A molecular sieves, CaH2, CaS04, BaO or sodium, being fractionally distd, and distd in a vacuum line just before use. Alternatively styrene (and its deuterated derivative) were passed through a neutral alumina column before use [Woon et al. J Am Chem Soc 108 7990 1986 Collman J Am Chem Soc 108 2588 1986]. 

Triethylsilane [617-86-7] M 116.3, b 105-107", 107-108", d 0.734, n 1.414. Refluxed over molecular sieves, then distilled. It was passed through neutral alumina before use [Randolph and Wrighton J Am Chem Soc 108 3366 1986],... 

A solution of 50 g. of j-tolylsulfonylmethyl isocyanide in 150 ml. of dichloromethane is placed on a 40 x 3 cm. column containing about 100 g. of neutral alumina slurried in dichloromethane. A nearly colorless solution (ca. 700 ml.) is collected over about 1 hour. This solution is evaporated to dryness on a rotary evaporator, providing 42—47 g. of white -tolylsulfonylmethyl isocyanide, m.p. 113-114° (dec.). 

It has been claimed that the elimination of tosylates of 3a-alcohols in 5jS-series gives 3-oleflns with high selectivity. However, the homogeneity of these products is questionable, in view of recent findings concerning the ehmination of 3-chloro compounds (see below) and Fieser s results with the elimination of methyl lithocholate tosylate (ref. 232, cf. ref. 233). Neutral alumina may also be used to effect elimination of tosylates of 3j5-alcohols if the alumina is pretreated with potassium hydroxide the inverted alcohol is the predominant product. 

Action of anhydrous neutral alumina on gem-difluorocycloalkanes (see section VI) is a convenient general route to cyclic vinyl fluorides. ... 

A solution of 5 g (14 mmoles) of 5a-cholest-2-ene in 100 ml ethyl acetate and 8 ml of 2.8 M (22 mmoles) cyanogen azide (CAUTION See Chapter 15 and ref. 139b) in ethyl acetate is heated at 50-53° for 24 hr, during which time about 22 mmoles of nitrogen is evolved. Solvent is removed by evaporation and the residue is applied in benzene to a column of 160 g of neutral alumina (activity grade III). Elution with petroleum ether-benzene (1 1) gives 1.6 g of... 

Preparation of 18,20-Cyclo-5a-pregnane-3, 20-diol 3-Acetate ° A solution of 5 g of 3j9-hydroxy-5oc-pregnan-20-one 3-acetate in 1000 ml of spectroscopically pure ethanol is irradiated with a 250 Watt Philips Biosol A mercury high pressure lamp No. 10/27 through a cental water cooled pyrex jacket under nitrogen for 4 hr. The solvent is then evaporated under reduced pressure and the residues from 2 such reactions are combined and chromatographed on 300 g of neutral alumina (activity II). 

A solution of 0.3 g of the foregoing crude acid dissolved in 7 ml of t-butanol and 0.4 ml of concentrated hydrochloric acid is refluxed for 20 min. The cooled reaction mixture is diluted with benzene, washed with saturated sodium bicarbonate solution, and with water, dried and evaporated under reduced pressure. The neutral residue (0.21 g) dissolved in benzene is adsorbed on a column of 2.5 g of neutral alumina. Elution with ether-petroleum ether gives 0.18 g of 19-norprogesterone mp 141-142°, after two crystallizations. 

Bromo-4-methoxy-A-homo-estra-2,4,5(10)-trien-17-one (44 0. 2g), is dissolved in formic acid, 2 ml of boron trifluoride etherate is added and the mixture is stirred vigorously at 0° for 2 hr. A brown mass ca. 0.12 g) is obtained after evaporation of the solvents at reduced pressure. This material is diluted with water and extracted with chloroform. The chloroform extracts are washed successively with water and saturated salt solution, dried over anhydrous magnesium sulfate and evaporated at reduced pressure to give 95 mg of a product which is purified by filtration through a column of neutral alumina and crystallization of the residue after evaporation of the solvent from ethyl acetate-petroleum ether. The resulting A-homo-estra-l(10),2,4a-triene-4,17-dione (45), mp 143-146°, is identical to the tropone (45) prepared from monoadduct 17-ketone (43a). 

Apparently the role of methanol is to intercept unstable species which otherwise tend to polymerize or rearrange. The methoxy peroxide (72) can be isolated in crystalline form if desired, but it is preferable to treat the methylene dichloride solution at 0° with zinc dust and acetic acid until the mixture shows a negative potassium iodide test. The resulting crude seco-aldehyde (73) is then cyclized to (74) by stirring with neutral alumina in benzene at room temperature for 3 hr. ° Wechter has recently reported a number of transformations of a 5yS-hydroxy-6yS-formyl-B-norpregnane prepared in 8% yield by photolysis and hydrolysis of a 5a-hydroxy-6 -azidopregnane. 

After stirring for 1 hr more, the reaction mixture is diluted with 500 ml of cold water the yellow precipitate which forms is filtered, washed and dried, to give 4.1 g (83%) of crude 16-diazoestrone methyl ether (94) mp 133-136°. Chromatography of the crude product over neutral alumina in chloroform, followed by recrystallization from chloroform-methanol, gives pure (94) mp 145-146°, in 64% over-all yield. ... 

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