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Ethanol, azeotropic drying

Table 6.2 lists the ultraviolet cutoff for a variety of solvents commonly used in UV-VIS spectroscopy. The solvent chosen must dissolve the sample, yet be relatively transparent in the spectral region of interest. Typically, very low concentrations of sample will be present in the solvent. It is therefore important to avoid solvents that have even weak absorptions near the solute s bands of interest. Methanol and ethanol are two of the most commonly used solvents. Care must be exercised when using the latter that no benzene (an azeotropic drying agent) is present as this will alter the solvent s transparency. Normally, this will not be a problem in spectral grade solvents. [Pg.654]

A mixture of the bis-phthaloyl starting material (16.6 g, 35.5 mmol), hydrazine hydrate (10.2 mL, 328 mmol), and ethanol (400 mL) was heated at 65 °C for 4 h. The mixture was filtered, and the cake was washed with toluene and azeotropically dried. The diamine was obtained at 85% yield. [Pg.203]

Compared to the corresponding control cigarette, the dry TPM [from a cigarette filled with reconstituted tobacco from which the wax layer had been removed by hexane-ethanol azeotrope extraction] had been reduced by 44%, the nicotine by 47% and catechol by 85%. This demonstrates a strong, selective reduction of catechols in the smoke by the removal of the wax layer. [Pg.510]

Slightly more than 1 mole bromine added dropwise at 0° to a stirred soln. of 366 g. acrolein in anhydrous ether, whidi is then removed in vacuo, the residue added to anhydrous ethanol containing dry HCl, refluxed several hrs., distilled at 45-50° until no more ethyl halide is evolved, benzene added, and the water-ethanol-benzene azeotrope collected in a Dean-Stark trap 2-bromo-l,l,3-tri-ethoxypropane. Y 76%. J.N. Wells and M. S. Strahl, J, Pharm. Sci. 60, 533 (1971). [Pg.370]

The following azeotropes are important commercially for drying ethanol ... [Pg.13]

To a stirred and refluxing solution of 40 parts of benzene and 35 parts of dimethylformamide (both solvents previously dried azeotropically) are added successively 1.6 parts of sodium hydride and 7.7 parts of Ct-(2,4-dichlorophenyl)imidazole-1-ethanol, (coolingon ice is necessary). After the addition is complete, stirring and refluxing is continued for 30 minutes. Then there are added 7.8 parts of 2,6-dichlorobenzyl chloride and the whole is stirred at reflux for another 3 hours. The reaction mixture is poured onto water and the product 1-[2,4-dichloro-/3 (2,6-dichlorobenzyloxy)phenethyl] imidazole, is extracted with benzene. The extract is washed twice with water, dried, filtered and evaporated in vacuo. The bese residue is dissolved in a mixture of acetone and diisopropyl ether and to this solution is added an excess of concentrated nitric acid solution. The precipitated nitrate salt is filtered off and recrystallized from a mixture of methanol and diisopropyl ether, yielding 1-[2,4-dichloro- (2,6-dichlorobenzyl-oxv)phenethyl] imidazole nitrate melting point 179°C. [Pg.843]

The quality of the ethanol has a strong influence on its corrosive effects. Three categories of problems have been identified general corrosion (caused by ionic impurities, mainly chloride ions and acetic acid), dry corrosion due to ethanol polarity, and wet corrosion caused by azeotropic water. Corrosion inhibitors should thus be incorporated in ethanol-diesel blends. [Pg.195]

A stirred solution of 13.0 g (100 mmol) of 5-oxohexanoic acid and 17.5 g of (1, S. 2.S )-2-amino-1-phcnyl-1,3-propanediol is heated under reflux in benzene for 16 h with azeotropic removal of water. The solution is concentrated and the residue is dissolved in 600 mL of diethyl ether. The solution is washed with sat. aq NH4C1, water, sat. aq Na2C03 and brine before drying over MgS04 and concentration in vacuo to give a colorless oil yield 24 g (96%) 84 14 2 mixture of isomers (the major isomers are diastereomers while the minor isomer is a regioisomer). Rccrystallization from ethyl acetate/hexane furnishes colorless needles yield 15.7g(60%) mp98-99°C [ ]D +13.3 (c = 1.1, ethanol). [Pg.870]

A 4-arm polyethylene glycol having an Mn of 10,000 Da (8 mmol of hydroxyl groups) was dried by azeotropic distillation using 400 ml of chloroform. The residue was then redissolved in 300 ml chloroform and cooled to 4°C and then treated with triethylamine (14.4 mmol) and methanesulfonyl chloride (13.2 mmol). The mixture was stirred overnight at ambient temperature and then treated with 5 ml of ethanol and stirred an additional 30 minutes. It was dried using sodium carbonate (10.0 g), concentrated, and filtered. The filtrate was concentrated to dryness and treated with 400 ml of 2-propanol. The precipitate was collected and 20.0 g product isolated having a 95.3% methanesulfonate substitution. [Pg.464]

The step 2 product (2.0 mmol) was dried by azeotropic distillation, redissolved in 80 ml ethanol, and treated with the step 1 product (7.2 mmol). The mixture was... [Pg.464]


See other pages where Ethanol, azeotropic drying is mentioned: [Pg.367]    [Pg.478]    [Pg.310]    [Pg.312]    [Pg.506]    [Pg.1086]    [Pg.1283]    [Pg.60]    [Pg.506]    [Pg.93]    [Pg.137]    [Pg.367]    [Pg.478]    [Pg.367]    [Pg.478]    [Pg.156]    [Pg.156]    [Pg.60]    [Pg.188]    [Pg.511]    [Pg.182]    [Pg.188]    [Pg.284]    [Pg.1543]    [Pg.26]    [Pg.62]    [Pg.62]    [Pg.143]    [Pg.145]    [Pg.234]    [Pg.236]    [Pg.279]    [Pg.53]    [Pg.117]    [Pg.90]    [Pg.328]    [Pg.192]    [Pg.273]   
See also in sourсe #XX -- [ Pg.11 ]




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