Nitrogen-aqueous ethanol system

Figure 6. Gas holdup as a function of radial position for nitrogen-aqueous ethanol system.

Figure 10. Effect of solids on radial distribution of Sauter mean bubble diameter in nitrogen-aqueous ethanol system.

HU-211 is highly liposoluble, which makes it readily accessible to the central nervous system since it readily crosses the blood brain barrier. However, its poor solubility in water hampers development of formulations suitable for i.v. administration. In order to overcome this drawback, Popp et al. have prepared a series of water-soluble salts of glycinate esters (attached to the allylic hydroxyl) and salts of amino acid esters containing tertiary and quaternary nitrogen heterocyclics (attached to the phenolic hydroxyl) (see Figure 5.5) [201, 202]. Most of the new compounds were relatively soluble in water or 10% aqueous ethanol, and showed neuroprotective properties, attributed to the parent compound, formed on hydrolysis of the esters in vivo. 

A 250-mI round-bottom flask fitted with a condenser (drying tube) is charged with a mixture of 2-bromocholestanone (4.7 g, 0.01 mole), lithium carbonate (7.4 g, 0.10 mole), and 100 ml of dimethylformamide. The system is flushed with nitrogen and then refluxed (mantle) for 18-24 hours. After the reflux period, the solution is cooled and poured into 500 ml of water. The aqueous mixture is extracted with 50 ml of ether, the ether extract is dried (sodium sulfate), and the ether is removed (rotary evaporator). The residue may be recrystallized from ethanol or methanol. J -Cholestenone is a white solid, mp 98-100°. 

The reduction of various substrates by dissolving metals in alcoholic and aqueous media is a very old procedure in synthetic organic chemistry. In addition to aldehydes, ketones, imines and other unsaturated nitrogen compounds, many other functional groups are reduced under these conditions. Historically, the most common reduction conditions were Na in ethanol, and the reductions were carried out by adding the metal to a solution of the substrate in alcohol and the reaction mixture was heated at reflux for varying periods of time. Other reduction systems included Na-Hg amalgam in water or alcohols and, for easily reduced compounds such as aldehydes and aromatic ketones, Zn-NaOH or Fe-acetic acid have been used. ... 

Tetraphenyltellurophene 1,4-Diiodotctraphcnyl-l, 3-butadiene is prepared by reaction of diphenylacetylene with lithium in diethyl ether and treatment of the resultant suspension with iodine. A 250 ml, three-necked flask is fitted with a reflux condenser, a stirrer, and a gas-inlet tube. The system is flushed with nitrogen, 1.5 g (11 mmol) of finely powdered lithium telluride, 2.0 g (3.3 mmol) of 1,4-diiodotetraphenyl-l, 3-butadiene, and 125 ml of 2-ethoxyethyl ethyl ether are placed in the flask. The mixture is stirred and heated under reflux for 8 h, cooled, and poured into 1000 ml of water. The organic layer is separated, the aqueous phase is extracted with benzene, and the combined organic phases are dried with magnesium sulfate. The organic layer is filtered, the filtrate is evaporated, and the residue is recrystallized from dichloromethane/ethanol (charcoal) yield 1.3 g (82%) m.p. 239 . 

The flame-based detector was reported to accept in excess of 20 ui/mln of 10-25Z aqueous methanol without extinction of the flame Optimum response was obtained at flow rates below 5 iii/min. Compatible solvent systems were aqueous methanol (up to 50%), acetone and ethanol (up to 40%) The minimum detectable quantity (at 5 times noise) measured for the FPD was 2 pg P. The dual-flame TSD can also be directly Interfaced with mlcrocaplllary packed columns The TSD was reported to be compatible with 75 to 100% aqueous methanol The utilization of microbore column LC-TSD for the analyls of nitrogen, phosphorous, and halogen containing compounds is particularly Important in studies of biomolecules, and drugs and their metabolites in physiological fluids ... 

Polymerization. Copolymers of tetrafluoroethylene/perfluoro(methyl vinyl ether) and the nitrile (1-4 mole ) have been prepared batch-wise in a stirred autoclave using an aqueous ammonium persulfate or ammonium persulfate-sodium sulfite redox couple system at 40°-100° C. The TFE/PMVE gas mixture was pressured, as required, to maintain the pressure and the nitrile pumped in solution in trichlorotrifluoro-ethane. After completion of the reaction, polymer was isolated from the latex (25-30 solids) by coagulation using ethanol and aqueous magnesium chloride solution. It was washed with alcohol/water solutions and dried at 70 °C in an oven under nitrogen. Mass balance indicated that most of the nitrile had been incorporated. 

Zinc nitrate (Zn(N03)2, Aldrich) was dissolved in ethanol and an aqueous solution of ammonium hydroxide was added drop by drop until the metal hydroxide was dissolved completely. Then an alcoholic solution of 1-dodecanethiol was added to this system at room temperature, under stirring, and the precipitate was isolated by vacuum filtration. The Zn mercaptide, Zn(SCi2H25)2, obtained was dissolved in chloroform and blended with polystyrene, leading to translucent films after solvent removal. The thermal annealing of zinc mercaptide/polystyrene blends, performed under nitrogen, at 250°C, gave a nanoscopic ZnS phase. 

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