Alumina chromatography

The mixture is dned (Na2S04), filtered (celite pad) arxJ evaporaled Chromatography (alumina 2% Et20 in pentane) afforded 144 mg of 5 (96%)... 

A solution of 2,4-dichloro-2,.3-dihydro-1-benzothiepin (0.5 g, 2.16 mmol) in f-BuOH (14 mL) was added in one portion to a solution of f-BuOK (246 mg, 2.20 mmol) in t-BuOH (24 mL). After stirring for 50 min, the turbid orange solution was poured into H20 (150mL) and extracted with CHCl3. The extract was washed with H20 and dried (MgS04). The solvent was removed under reduced pressure to give a yellow oil [yield 330 mg (79%)] which was further purified by chromatography (alumina, petroleum ether). 

Benzo-3-thiatricyclo[4.1.0.02 7jheptene was reacted with 7.8 mol % Rh(acac)(CO)2 in CHClj at O t to yield pale-yellow needles mp 24 DC. Purification was by column chromatography (alumina) at — 20 SC. All manipulations during workup must be performed below — 10 DC to prevent thermal extrusion of sulfur. 

The first reported example31,117 involved the diethyltetraphenyl-3//-azepines 18 and 19 which were obtained in 85% overall yield by the reaction of2,3-diethyl-2//-azirine with 2,3,4,5-tetraphenylcyclopentadienone (see Section 3.1.1.1.2.). The two isomeric azepines are separable by column chromatography (alumina or silica gel), and each isomer, on warming in xylene for three days, equilibrates to a 3 8 mixture of the 3//-azepines 18 and 19. 

An iron tricarbonyl complex 19-21 (0.338 g, 1 mmol) and freshly sublimed Me3NO (0.6 g, 8 mmol) in acetone was left at rt for 4h. Evaporation, followed by flash chromatography (alumina, Et20), gave the corresponding unstable l-troponyl-l//-l,2-diazepines 22-24 in 76, 76 and 44% yield, respectively. 

A solution of 9a (0.100 g, 0.7 mmol) and NaOMe (0.020 g, 0.35 mmol) in MeOH (20 mL) was stirred at 20 C for 4 h and evaporated in vacuo below 30X. The residue was extracted with Et20, and the extract was washed with H20, dried (MgS04) and evaporated. Chromatography (alumina) of the residue gave 6a almost quantitatively. The homolog 9b behaved analogously. 

A mixture of Nd(OAc)3 (0.21 g, 1 mmol) and 4-/er/-hutylphthalonitriIe (7 1.47 g, 8 mmol) was fused in an evacuated glass ampule with gradual raising of the temperature to 290 JC and this temperature was then maintained for 2 h. The cooled melt was ground and purified by column chromatography (alumina, benzene) to ohtain a blue powder yield 1.03 g (60%). 

Diheptylnaphthalene-2.3-dicarbonitrile (748 mg, 2 mmol), Fe(OAc)2 (174 mg, 1 mmol), and DBU (1.5 mL) were heated in hexan-1-ol (25 mL) for 3 h under reflux. The mixture was poured into MeOH/H20 (1 1, 150 mL). The black-brown precipitate was filtered, extracted with MeOH, and dried. The residue was stirred in a mixture of t-BuNC (1 mL) and CHC13 (5 mL) for 24 h at 60 C. The solvent and the excess t-BuNC were removed in vacuo. The residue was purified by column chromatography (alumina, CHClj) and dried in vacuo at 80°C to give a green powder yield 280 mg (42%). 

A mixture of metal-tree phthalocyanine (ABAB 50 mg, 0.027 mmol), anhyd Zn(OAc)2 -2H20 (50 mg, 0.27 mmol) and MeOCH2CH2OH/toluene (1 2, 10 mL) was heated at 120 C for 20 h under an argon atmosphere. The solution was then cooled and the product was purified by column chromatography (alumina, CHCl3/MeOH 4 1). A blue-green solid was obtained yield 45 mg (87%). 

The product is 97-98% pure by g.l.c. (Note 6) and is satisfactory for most purposes. If desired the adamantanone may be purified by either column chromatography (alumina, activity grade IV eluent ether) or by treatment with fuming sulfuric acid (20% free sulfur trioxide). For example 8.0 g. of adamantanone is added portionwise to 40 ml. of ice-cold fuming sulfuric acid. Then the solution is heated to 40° and maintained at this temperature for one hour. After pouring the mixture onto ice, the adamantanone is recovered by extraction with methylene chloride. 

Oxidation may be monitored by thin-layer chromatography (Alumina GF Uniplate, 1 1 ethyl acetate hexane). The Rf values of the N-oxide product and starting material are 0.30 and 0.79 respectively (Note 7). 

In THF solution the zirconacycles 70 and 72 reacted immediately at room temperature with main group electrophilic reagents affording main group heterocycles and zirconocene dihalide (equations 24 and 25) in about 80% yield. After removal of the solvent, the products can be easily extracted with hexane and isolated in the pure state by flash chromatography (alumina) with elution by hexane. 

A solution of N-(4-pyridinyl)-lH-indol-l-amine (6 g) in 25 ml of dimethylformamide was slowly added to an ice-cooled suspension of NaH (1.3 g of 60% NaH dispersion in mineral oil was washed with hexanes, the liquid was decanted and the residual solid was dispersed in 5 ml of dimethylformamide). After anion formation, a solution of 1-bromopropane (4 g) in 5 ml of dimethylformamide was added. After one hour of stirring at ambient temperature, the reaction mixture was stirred with ice-water and extracted with dichloromethane. The organic extract was washed with water and saturated sodium chloride solution, was dried over anhydrous magnesium sulfate, filtered and concentrated to 8 g of oil. This oil was purified by HPLC (silica, ethyl acetate) and thereafter by column chromatography (alumina, ether) to give 6.4 g oil. This oil was converted to the maleate salt and recrystallized from methanol/ether to give 6.8 g of crystals, m.p. 115-116°C. 

This was separated into two components by centrifugal chromatography (alumina,... 

Column Adsorption Chromatography. Almost all of the remaining interferences are eliminated by column adsorption chromatography. Alumina is more effective than silica gel or Florisil (4,5). 

A mixture of well-dried (60 C/0.1 Torr, 3 h) 1,8-dichloroanthraquinone (8.0 g, 28.8 mmol) and anhyd CsF (16.0g. 105.2 mmol) in anhyd DMSO (35 mL) was stirred for 10 h at 135 C under argon. After cooling to rt, the mixture was poured into ice water, and the precipitate filtered, washed with H20 (4x250mL) and MeOH (50 mL), and dried in vacuo. The crude material was purified by chromatography (alumina, CH2Cl2/hexane 1 1) to give 6 yield 4.22 g (60%) mp 228-229°C. 

Bulk matrix removal aims to remove material such as lipids which can disturb final analysis. This can be performed by acid treatment of the extract or by liquid-solid chromatography. Alumina fractions of chlorophenol extracts have been purified with concentrated sulfuric acid [37,38] and it has been used to remove lipid and organic coextractives in sediment, biota, and human extracts [33,43,57,58,113,114,120,122-125]. The sulfuric acid treatment of PCDEs has been reported not to affect their recoveries [58]. 

Crystalline alumina may exist in various forms the T-form is generally used in chromatography. Alumina strongly adsorbs water molecules, as depicted in Fig. 1. The two different hydroxyl groups show acidic or alkaline properties, resulting in amphoteric characteristics and ion exchange behavior of the alumina surface, as demonstrated in Fig. It has been further shown that the... 

A further example for the analysis of trace levels of pollutants is the determination of polychlorinated diben-zodioxins and polychlorinated dibenzofurans in milk. The method includes gel permeation chromatography, alumina cleanup, and porous graphitized carbon chromatography, followed by analysis by gas chromatography-... 

Earlier fluorometric methods for analysis of urinary free catecholamines have been replaced by HPLC methods that allow selective quantitation of epinephrine, norepinephrine, and dopamine. Preliminary extraction of urine is stid required and numerous preanalytical cleanup techniques are available. An alumina extraction procedure is typically coupled with ion-exchange or adsorption chromatography. Alumina pretreatment usually involves a batch extraction technique in which catechols are first adsorbed at pH 8.6 and then eluted with boric acid, which forms a complex with cis-diol groups. Purification on boric acid affinity gels provides an alternative procedure for selective adsorption of catecholamines. 

Before the reaction was started the air was displaced from the reaction system with argon. A solution of diphenyldiazomethane (10.5 g, 54 mmol) in freshly distilled butyl vinyl ether (50 mL) was then added drop-wise to a boiling solution of anhyd CuSO (0.3026 g, 1.90 mmol) in butyl vinyl ether (100 mL) with stirring for 4 h. When no more Nj was liberated (780 mL, 64.5yo), the mixture was cooled (in an atmosphere of argon) and the catalyst filtered off. Butyl vinyl ether was distilled off under vacuum and the resulting residue, after separation of benzophenone azine which had crystallized out, was fractionated under vacuum. A light-yellow distillate (11.1 g bp 133-155 C/0.2 Torr), which was a mixture of l-butoxy-2,2-diphenyl-cyclopropane (1), benzophenone azine (2) and benzophenone (3), was obtained. The cyclopropyl ether was isolated from this mixture by means of column chromatography (alumina activity II, hexane/EtjO 10 1) and was finally purified by vacuum distillation yield 2.36g (16%) bp 78 - 79°C/0.015 Torr. 

The reaction of 2,3-bis(diisopropylamino)cyclopropenethione with an equimolar amount of 2,3,5- or 2,3,4-tricyano-l -phenyliodoniocyclopentadienide in refluxed chloroform for 1.5 hours, followed by column chromatography (alumina, dichloromethane) afforded the thioxo ylides... 

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