Nitrogen, oxygen-free

Pure nitrogen (oxygen-free), at a flow rate of 40 mL min is used as carrier gas. The dimensions of the glass column are 1.6 m length and 6 mm o.d., and it is packed with 5 per cent by weight SE-30 on Chromosorb W as the stationary phase. The column is maintained at a temperature of 165 °C. 

Gases Air, nitrogen, oxygen (free from CO2 and organic impurities). 

Tests of effects of pH were carried out at room temperature. The influence of anaerobic and aerobic conditions were evaluated by purging the reaction mixture with oxygen or nitrogen (oxygen-free). Spectra were recorded after 15 min, 24 hours and 96 hours. Ames tests were done after 24 hours. 

To a 250-ml 3-necked flask equipped with a magnetic stirring bar, condenser, thermometer, and gas inlet-outlet is added a benzene solution (toluene can be used in place and is less toxic) of 10.77 gm (0.1098 mole) of maleic anhydride and 0.04514 gm (1.863 x lO"" mole) of benzoyl peroxide. Dry nitrogen (oxygen-free) is flushed for 45 min through the flask, and then 9.11 gm (0.1214 mole) of ethyl vinyl ether is injected into the flask via a septrum seal on one of the necks. The reaction mixture is stirred and heated for 8 hours at 59°-61°C. The white precipitate is filtered and dissolved in 125 ml of acetone. The product is isolated from the acetone by gradually... 

Oxygen-free nitrogen in cylinders is available commercially but is, of course, more expensive than the normal commercial compressed gas. 

If preferred, the apparatiaa depicted in Fig. II, 7, 13 may be used. This enables an oxygen-free nitrogen atmosphere to be maintained in the apparatus and leads to the best yield of phenyl-lithium. 

Add 40 ml. of ethyl alcohol to 21 -5 g. of 70 per cent, ethylenediamine solution (0 -25 mol) dissolve 36 -5 g. of adipic acid (0 -25 mol) in 50 ml. of a 6 1 mixture of ethyl alcohol and water. Mix the two solutions, stir and cool. Filter off the resulting salt and recrystalliae it from 60 ml. of a 6 1 ethyl alcohol - water mixture, and dry the salt in the air. Heat the salt in an atmosphere of oxygen-free nitrogen or of carbon dioxide in an oil bath until it melts (ca. 160°) the product will sohdify after a short time. Reduce the pressure to 15 mm. of mercury or less and raise the temperature of the oil bath until the product remelts (about 290°) and continue the heating for 4r-5 hours. Upon coohng, a nylon type polymer is obtained. 

Compound 36 when treated by sulfur under nitrogen, leads to the thiazoline-2-thione (37) (Scheme 16) (43). Oxidation by O- or air of 36 (43) or 38 (45, 46) leads to the corresponding thiazoiine (39 or 40). Consequently, condensation reactions using catalysts like 36 must be run in strictly oxygen-free atmosphere (47-50). The isolation of traces of 3-benzyl-4-methyl-A-4-thiazoline-2-one (42) as a product of the oxidation of... 

The majority of thermal polymerizations are carried out as a batch process, which requires a heat-up and a cool down stage. Typical conditions are 250—300°C for 0.5—4 h in an oxygen-free atmosphere (typically nitrogen) at approximately 1.4 MPa (200 psi). A continuous thermal polymerization has been reported which utilizes a tubular flow reactor having three temperature zones and recycle capabiHty (62). The advantages of this process are reduced residence time, increased production, and improved molecular weight control. Molecular weight may be controlled with temperature, residence time, feed composition, and polymerizate recycle. 

Products of Combustion For lean mixtures, the products of combustion (POC) of a sulfur-free fuel consist of carbon dioxide, water vapor, nitrogen, oxygen, and possible small amounts of carbon monoxide and unburned hydrocarbon species. Figure 27-12 shows the effect of fuel-air ratio on the flue gas composition resulting from the combustion of natural gas. In the case of solid and liquid fuels, the... 

Perylene [198-55-0] M 252.3, m 173-214°. Purified by silica-gel chromatography of its recrystd picrate. [Ware J Am Chem Soc 83 4374 1961.] Crystd from benzene, toluene or EtOH and sublimed in a flow of oxygen-free nitrogen. [Gorman et al. J Am Chem Soc 107 4404 1985 Johansson et al. J Am Chem Soc 109 7374 1987.]... 

The irradiations are in general performed under purified, oxygen-free nitrogen in a cylindrical irradiation apparatus with a water-cooled central sleeve into which the lamp is introduced and efficient cooling is used to keep the temperature between 10° and 0° C. Temperatures in the range of 0° to 80° do not influence the photolysis step as demonstrated in the case of a 6j -nitrite, but increase the rate of rearrangement of the nitroso derivative to the oxime. 

The use of oxygen-free (pyrrogaVlol-washed) nitrogen seems essential private communication from Dr. M. E. Wolff, University of California, San Francisco. 

The hrazing of copper tuhe will leave a layer of copper oxide inside, which may become detached and travel around the circuit. The best practice is to pass nitrogen into the pipe before heating, to avoid this oxidation. The use of special grades of oxygen-free or moisture-free nitrogen is not necessary. 

The nitrogen is dried by passing it through concentrated sulfuric acid. It must be nearly oxygen-free otherwise 1.3-di-phenylimidazolidinone-2 is formed, and its removal by recrystallization results in a decreased yield. 

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