Traces of oxygen

Note 1. In view of the strong foaming, a 500-ml distillation flask should be used. Note 2. Traces of oxygen cause polymerization of the cumulene and all operations... 

Note 2. Traces of oxygen will induce polymerization of the cumulene. The NMR tube must therefore be filled with nitrogen before putting the sample in it. Low-temperature NMR gives the most representative results. 

The typical fluorination apparatus used in the LaMar process for these reactions is simple in design (Fig. 4) (33). It is essential that the materials of constmction are resistant to fluorine (34). The presence of even traces of oxygen or moisture can have a deleterious effect and, therefore, extreme precautions must be taken to eliminate these contaminants. 

The impurities usually found in raw hydrogen are CO2, CO, N2, H2O, CH, and higher hydrocarbons. Removal of these impurities by shift catalysis, H2S and CO2 removal, and the pressure-swing adsorption (PSA) process have been described (vide supra). Traces of oxygen in electrolytic hydrogen are usually removed on a palladium or platinum catalyst at room temperature. 

The apparatus must be flushed with acetylene in order to remove all traces of oxygen. Acetylene dissolved in acetone is most appropriate. Acetylene obtained from tanks which contain solvents such as dimethylformamide (or other solvents) gave lower yields of carbocupration. 

Traces of oxygen in nitrogen used for inerting can react with some products, such as butadiene and acrolein, and cause explosive polymerization. In one case, unknown to the acrolein plant, a trace of oxygen was deliberately added to the nitrogen supply at the request of another plant. 

Sterilised sealed cans of foodstufifs, including fruit, vegetables, meat, fish and milk, which should contain only residual traces of oxygen. Cans for beer and soft drinks. 

Anaerobic Bacteria (anaerobes) group of bacteria that are unable to multiply in anv but a minute trace of oxygen. 

The solution of purified dinoflagellate luciferin is yellow, showing absorption maxima at 245 and 390nm in an aqueous solution and at 241 and 388 nm in 40% acetonitrile containing 85 mM NaCl and 3 mM NaHCOs (Fig. 8.4). The compound is strongly fluorescent in blue (excitation maximum at 390 nm, emission maximum at 474 nm Fig. 8.5). The properties of this luciferin are nearly identical with those of the compound F of euphausiid shrimps (Section 3.2). The luciferin is rapidly oxidized in the presence of a trace of oxygen, and also inactivated by a weak acid, even by an acidity of pH 4 or the acidity... 

As has been discussed at length in this book, it is almost always necessary to remove all traces of oxygen in the boiler plant system to protect... 

Unavoidable traces of oxygen in the raw material (e.g., up to 70 mg 02/L alkane at 20°C) and of water in the ppm range produce between 0.1% and 0.5% free alkanesulfonic acid and some sulfuric acid in the product. 

For ZnS and CdS, it is important to exclude all traces of oxygen since these materials are easily oxidized ... 

Ethylene Free radical at pressures up to 2000 atmospheres at 100 to 200°C using traces of oxygen or aqueous persulfate as catalyst —CHr-CHj— T , = 110 to 130 Waxlike, highly crystalline, very strong when oriented. Insoluble in all solvents at temperatures much below Tm... 

Oxidation of sulfide ions to thiosulfate by traces of oxygen... 

Note that expressions (2.24 ) and (2.36) are applicable for equilibrium adsorption of molecular gases. Moreover, this dependence becomes valid during adsorption of oxygen too when the latter is diluted in polar liquids such as H2O, CH3OH, C4H9OH, CgHi2 etc. [59]. The results of these studies related to evaluation of possibility to detect the traces of oxygen in liquid media as well as plausible mechanisms of phenomena will be considered in detail in Chapter 4. 

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