Acid-washed alumina

Octene [111-66-0] M 112.2, b 121 /742mm, dj 0.716, n 1.4087. Distd under nitrogen from sodium which removes water and peroxides. Peroxides can also be removed by percolation through dried, acid washed alumina. Stored under nitrogen in the dark. [Strukul and Michelin J Am Chem Soc 107 7563 1985.]... 

The crude ketone is chromatographed on acid-washed alumina (600 g, activity II). Elution with hexane-ether (4 1) gives a white solid (8.5 g) as the major fraction mp 77-82°. Recrystallization from methanol gives A-homo-5a-cholestan-4-one (3b 5.77 g 41% yield) mp 86-88° ... 

The latter compound can be isolated from the reaction mixture by chromatography on acid-washed alumina. Similar treatment of the trans-ketone (117a) followed by isolation and chromatography on alumina gives the same equilibrium mixture. The structure of the thermodynamically more stable ketone (116a) was proved by its conversion by Wolff-Kishner reduction to the hydrocarbon (118) independently synthesized from the known... 

Phillips 1-octene of 99% minimum purity was used however, it was freed of peroxide by percolating through acid-washed alumina. 

Carbonate cleanup was successful in restoring extraction efficiency to radiolyzed solutions when the diluent was CC14 (40) or tetrachloroethylene (41). With paraffinic hydrocarbons as diluents, a secondary clean-up operation was needed (181). Several efficient sorbents have been proposed, for example, macroporous anion-exchange resins, acid-washed activated charcoal, acid-washed alumina (20), or basic alumina (46). 

For cleavages involving iPrOH/dioxane (up to 1 1), the latter should first be tested for the presence of peroxides by mixing it with an equal volume of 4% KI soln. If any brown color is formed after 1 min, remove the peroxides by passing the dioxane through a column of activated alumina (AI2O3). Not all commercially available activated alumina is effective Baker No. 0537 is satisfactory. Do not use acid-washed alumina. The same procedure is used to purify THF.td... 

The crude carotenoid is to be chromatographed on a 12-cm column of acid-washed alumina (Merck), prepared with petroleum ether (37-53°C) as solvent. Run out excess solvent, or remove it from the top of the chromatography column with a suction tube, dissolve the crude carotenoid in afew milliliters of toluene, and then transfer the solution onto the chromatographic column with a Pasteur pipette. Elute the column with petroleum ether, discard the initial colorless eluate, and collect all yellow or orange eluates together in a 50-mL Erlenmeyer flask. Place a drop of solution on a microscope slide and evaporate the rest to dryness (rotary evaporator or aspirator tube). Examination of the material spotted on the slide may reveal crystallinity. Then put a drop of concentrated sulfuric acid beside the spot and mix with a stirring rod. Compare the color of your test with that of a test on the other carotenoid. 

When colchicine is heated with acetic anhydride it gives the enol acetate (444, R=Ac), which is partially hydrolysed by acid-washed alumina to the iv-acetyl compound (444, R=H). This, on mild hydrolysis in alkalis, yields the ketone (445),... 

If the PMcj and dppe (diphenylphosphino ethane) PtLj analogues are used, complete hydrodesulfurization of DBT and 4-MeDBT to biphenyl and 3-Me-biphenyl, respectively, takes place under 20 atm H, at 100 °C interestingly, the presence of acid-washed alumina promoted the HDS reaction (see e.g. Eq. 4.9). Neither the fate of the sulfur nor the HDS mechanism is clear in this case [42, 43]. 

Stedman, R.L., A.P. Swain, and W. Rusaniwskyj Isomerization of terpenoid hydrocarbons by acid-washed alumina 1. Chromat. 4 (1960) 252-253. 

Sodium nitroprusside (SNP), hydrocortisone 21-hemisuccinate, desipra-mine hydrochloride, L-arginine hydrochloride, and w-conotoxin GVIA were purchased from Sigma Chemical Company (St. Louis, MO). Acid-washed alumina, sodium octyl sulfate, and catecholamine standards were purchased... 

Treatment of (-)-colchicine with acetic anhydride gives the enol acetate (168 R = Ac), which is hydrolysed to ( )-colchicine by acetic acid, and, on treatment with acid-washed alumina, yields the enol acetate (168 R = H). With aqueous base at room temperature (168 R - Ac) is converted into ( )-colchicine and the base (169). " The AT-mono-acetyl compound (168 R = H), on mild hydrolysis... 

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