Acetonitrile Acid potassium sulfate

Aluminum foil, Iodine powder. Carbon disulfide, 1,4,6,9-Tetrabromodiamantane, Sodium bisulfite. Hydrochloric acid. Methanol, Acetonitrile, Acetone, Sodium hydroxide. Magnesium sulfate. Potassium permanganate. Toluene Methylene chloride, 2-Bromomethanol, Trioxane, Aluminum chloride. Magnesium sulfate, Nitroform, Acetone, Sodium bicarbonate. Hexane, Silver nitrate. Acetonitrile 1,2-Dichloroethane, HexamethyldisUane, Iodine, Cyclohexane, 1,3-Dioxolane, Nitroform, Methylene chloride, Dimethylformamide, Sodium sulfate. Hydrochloric acid. Magnesium sulfate. Nitric acid. Sulfuric acid Sulfuryl chloride. Acetic anhydride. Nitric acid. Sodium bicarbonate. Sodium sulfate Nitric acid. Sulfuric acid, Malonamide Nitric acid. Sulfuric acid, Cyanoacetic acid Sulfuric acid, Acetasalicyclic acid. Potassium nitrate Nitroform, Diethyl ether, 1-Bromo-l-nitroethane, Sodium sulfuate... 

Sulfuric acid. Potassium nitrate, 1,3,5-Trifluorobenzene, Methylene chloride. Hexane, Charcoal, Sodium sulfate Phosphorus oxytrichloride. Ethylene dichloride, Dimethylamine, Sodium carbonate. Sodium cyanide. Ethyl alcohol. Acetonitrile Phosphorus oxytrichloride. Ethylene dichloride, Dimethylamine, Sodium carbonate. Sodium cyanide. Ethyl alcohol. Acetonitrile, Pyridine... 

The preferred solvent system used for the separation of flavonoids on reversed-phase stationary phases is methanol-water, followed closely by acetonitrile-water. Usually, acetic or formic acid is added (sometimes phosphoric acid, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and perchloric acid), which enables improved separation and prevention of peak tailing with respect to the phenolic character of the flavonoids. Ion pairing has also been used for improving the separation of neutral glycosides from flavonol sulfates. 

The solvents used were (a) HPLC grade methanol and acetonitrile (Fisher Scientific) (b) water, double-distilled and stored in glass. Inorganic salts and acid (ammonium sulfate, potassium phosphate monobasic, potassium phosphate dibasic and phosphoric acid, 85%) were analytical reagent grade (Malllnckrodt Chemical Works). 

Figure 14 Fractionation of 40-60-base oligodeoxyadenylates. Column 0.41 x 5 cm column packed with cross-linked and methylated PEI on Hypersil , 3 p. Eluent 50 mM potassium phosphate, 15% acetonitrile, pH 5.9 with a gradient from 200-500 mM ammonium sulfate. Flow rate 0.5ml/min. Oligomers of deoxyadenylic acid were fractionated up to a degree of polymerization of 60.180 (Reproduced with permission of Academic Press from Drager, R. R. and Regnier, F. E., Anal. Biodiem., 145, 47, 1985.)...

B. 2,2-(Trimethylenedithio)cyclohexanone. A solution of 3.02 g. (0.02 mole) of freshly distilled 1-pyrrolidinocyclohexene, 8.32 g. (0.02 mole) of trimethylene dithiotosylate4 (Note 2), and 5 ml. of triethylamine (Note 3) in 40 ml. of anhydrous acetonitrile (Note 4), is refluxed for 12 hours in a 100-ml., round-bottom flask under a nitrogen atmosphere. The solvent is removed under reduced pressure on a rotary evaporator, and the residue is treated with 100 ml. of aqueous 0.1 N hydrochloric acid for 30 minutes at 50° (Note 5). The mixture is cooled to ambient temperature and extracted with three 50-ml. portions of ether. The combined ether extracts are washed with aqueous 10% potassium bicarbonate solution (Note 6) until the aqueous layer remains basic to litmus, and then with saturated sodium chloride solution. The ethereal solution is dried over anhydrous sodium sulfate, filtered, and concentrated on a rotary evaporator. The resulting oily residue is diluted with 1 ml. of benzene and then with 3 ml. of cyclohexane. The solution is poured into a chromatographic column (13 x 2.5 cm.), prepared with 50 g. of alumina (Note 7) and a 3 1 mixture of cyclohexane and benzene. With this solvent system, the desired product moves with the solvent front, and the first 250 ml. of eluent contains 95% of the total product. Elution with a further 175 ml. of solvent removes the remainder. The combined fractions are evaporated, and the pale yellow, oily residue crystallizes readily on standing. Recrystallization of this material from pentane gives 1.82 g. of white crystalline 2,2-(trimethylenedithio)cyclo-hexanone, m.p. 52-55° (45% yield) (Note 8). 

Ethyl (2Z)-3-bromopropenoate. To a three-necked, round-bottomed flask are added lithium bromide (10.0 g, 0.115 mol, Note 1), acetonitrile (100 mL, Note 2), acetic acid (7.0 g, 0.116 mol, Note 3), and ethyl 2-propynoate (9.0 g, 0.092 mol, Notes 4, 5) under nitrogen. The reaction is carried out with magnetic stirring under reflux and monitored by GLC (Note 6). The reaction is complete after 24 hr. The reaction is cooled, water (20 mL) is added to the flask, and the mixture is cautiously neutralized with solid potassium carbonate, added in portions (Note 3). The organic layer is separated, and the aqueous layer Is extracted with ether (3 x 20 mL) (Note 3). The combined organic layers are dried with magnesium sulfate and filtered. After removal of the solvent, ethyl (2Z)-3-bromopropenoate is obtained by vacuum distillation (14.0 g, yield, 85%, Note 7). 

TNT, Sodium hypochlorite, Tetrahydrofuran, Methanol, Hydrochloric acid Aluminum foil. Iodine powder. Carbon disulfide, 1,4,6,9-Tetrabromodiamantane, Sodium bisulfite. Hydrochloric acid. Methanol, Acetonitrile, Acetone, Sodium hydroxide. Magnesium sulfate. Potassium permanganate. Toluene... 

Magnesium powder. Ferric oxide. Aluminum powder Potassium permanganate, Adamantane, Bromine, Sodium sulfite. Hydrochloric acid. Glacial acetic acid. Aluminum foU, Toluene, Methylene iodide. Acetonitrile, Tetrahydrofuran, Sodium hydroxide. Acetone, Magnesium sulfate. Aluminum chloride. Chloroform... 

Acetonitrile contains water, ammonia, hydrogen cyanide, and acetic acid as impurities. Water is removed by sodium sulfate,36 basic constituents by phosphoric oxide,37 and acidic impurities by distillation from potassium carbonate. 

Several extraction techniques have been reported in the literature for the analysis of sulfonamides. Because of their polar nature, sulfonamides are readily extracted by organic solvents ° ° the most commonly used are acetonitrile.Other organic solvents used for analyte extraction and protein precipitation include dichloromethane, " acetone, ethanol, chloroform, and ethyl acetate, " which are often used either alone or in conjunction with one another. Other techniques used for protein precipitation include the use of acids such as perchloric or formic and the use of basic buffers such as potassium hydrogen phosphate and ammonium sulfate. In the case of honey, the use of acids such as trichloroacetic, " " hydrochloric, and phosphoric is necessary for hydrolysis, releasing carbohydrate-bound sulfonamide residues. Other extraction techniques reported in the literature include the use of pressurized liquid extractions, " matrix solid-phase dispersion, and magnetic molec-ularly imprinted polymers. Of additional note, several authors have observed that analyte recoveries were largely... 

The chemicals used in this study were sodium chloride, magnesium chloride, calcium chloride, potassium chloride, trichloroacetic acid (TCA), trifluoroacetic acid, a-d glucose, sodium citrate dihydrate, sodium hydrogen phosphate, hydrochloric acid, and iron (II) sulfate heptahydrate. These chemicals were purch d from Sigma (St. Louis, MO, USA). The HPLC gr e solvent, acetonitrile was fivm J. T. Baker (Philipsburg NJ, USA). Water was distilled and deionized prior to use. 

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