Atmosphere of oxygen

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. 

The cobalt deposition rate on new, replacement, or decontaminated recirculation piping surface has been reduced by pretreating the piping using an atmosphere of oxygenated wet steam to form an oxide film (25). Studies have been conducted for both PWRs and BWRs to reduce the cobalt content of materials used in the nuclear parts of the plants, particularly in hardened and wear surfaces where cobalt-base alloys ( 50% Co) are used (26). Some low cobalt materials have been developed however, the use of the materials is limited to replacement parts or new plants. 

The thermodynamics of the 123 compound have been extensively studied and writing dre formula as (YBa2Cu3)Oj. it has been shown that at 1000 K the value of z changes from 6 to 6.6 in dre oxygen pressure range 10 " to one atmosphere of oxygen. Above this temperature, the 123 compound decomposes to 211 plus barium cuprate and cuprous oxide according to the reaction... 

It should be stable to heat even in an atmosphere of oxygen up to the softening point and possibly beyond. 

A solution of ketone (85) in t-butanol and excess potassium -butoxide and potassium hydroxide is heated at refluxjinder an atmosphere of oxygen for 8 hr to give the C-norpregnane acid (87), in about 46% yield. Yields tend... 

Kharasch and coworkers were the first to show that thiols and olefins cooxidize in an atmosphere of oxygen at room temperature to yield substituted 2-sulphinylethanols 81 (equation 45). Later on, it was demonstrated that a-mercapto-substituted hydroperoxides are formed as intermediates. Thus, Oswald found that cooxidation of thiophenol with styrene gave the corresponding 8-mercaptohydroperoxide 82 which subsequently underwent rearrangement to 2-phenylsulphinyl-a-phenylethanol 83 (equation 46). 

However, by heating the ore in an atmosphere of oxygen, pyrrhotite is converted to hematite ... 

Deaerated water is prepared as follows. A boiling stone is added to distilled water which is then boiled under reflux for at least 5 minutes it is cooled in ice to room temperature under an atmosphere of oxygen-free nitrogen. 

Shortly after mercury was accidentally introduced into a system containing a solution of anthracene in carbon disulfide under an atmosphere of oxygen, an explosion occurred. Presence of mercury may have catalysed rapid oxidation of carbon disulfide. 

Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

It should be noted that in some papers (53, 57) the specimens of zinc oxide were preliminarily calcined in an atmosphere of oxygen, i.e., the surface of the catalyst was enriched in the adsorbed oxygen. 

Sharp [48] has described a dry combustion-direct injection system built for oceanographic analyses. This unit used 100 xl samples, injected into a 900 °C oven in an atmosphere of oxygen. The output from a non-dispersive infrared carbon dioxide analyser was linearised and integrated. 

Hydrated RuCl, (1.5 g, ca. 6.2 mmol) is stirred with sodium periodate (5.5 g, 26 mmol) in H20 (50 ml) for 12 h. The precipitated ruthenium oxide is added at 0-5°C under an atmosphere of oxygen to aqueous TPA-OH (1M, 5 ml) and aqueous NaOH (0.8 M, 50 ml). Precipitated TPA-Ru04 (87%) is collected and washed well with H20 and dried under vacuum. 

The oxygen index is the minimum percentage of oxygen in an atmosphere of oxygen and nitrogen that sustains the flame of an ignited polymer sample. 

Let us compare M-ZSM-5 zeolites with M = H+, Li+, Na, K+, Rb, Cs, AF+, on one hand, and organic electron donors of variable ionization potentials, on the other. Zeolite H-ZSM-5 generates cation-radicals from substrates with an oxidation potential of up to 1.65 V (Ramamurthy et al. 1991). The naphthalene sorption by Al-ZSM-5 zeolites calcified in an atmosphere of oxygen or argon leads to the appearance of two occluded particles—the naphthalene cation-radical and isolated electron. Both particles were fixed by ESR method. Back reaction between the oppositely charged particles proceeds in an extremely slow manner and both the signals persist over several weeks at room temperature (Moissette et al. 2003). 

Ladizesky and Ward (1983, 1989), Ward and Ladizesky (1986) and Ward (1993) reported that plasma treatment of polyethylene fibers in an atmosphere of oxygen is the most effective among the many techniques studied. There are four major mechanisms responsible for improved fiber-matrix interface adhesion ... 

High temperatures are generally needed in solid state synthesis to improve reaction rates and to facilitate solid state diffusion. Solid state diffusion is typically very slow. Thus, mechanical grinding steps are important to homogenize the sample and encourage complete reaction. It is important to realize, however, that some phases decompose at elevated temperatures. For example, Ba CujOy is unstable above about 1050°C (1) and the related phase, BajYCUjOg is only stable to 860°C in one atmosphere of oxygen (2). Thus, efforts to prepare these phases require a balance between the heat put in to speed the reaction kinetics and the stability limits of the desired phase. 

The preparation of some compounds must be carried out under a special atmosphere an Inert gas such as argon may be used to prevent oxidation to a higher oxidation state, an atmosphere of oxygen can be used to encourage the formation of high oxidation states or conversely a hydrogen atmosphere can be used to produce a low oxidation state. 

Voltz and Weller 14S) measured the activity of chromic oxide for hydro-gen-deuterium exchange at —78° and —195°, after pretreatment at 5(X)° in an atmosphere of oxygen or hydrogen. They found the catalytic activity of the reduced state to be higher than that of the oxidized state, although the latter had a higher concentration of defects (positive holes) responsible for electrical conductivity. The relation between catalytic activity and conductivity is thus opposite to that for zinc oxide, although in both cases the activity appears to increase with the electron concentration. The interpretation advanced earlier for zinc oxide has also been extended to chromic oxide (Baker and Jenkins, 14S). 

In an atmosphere of oxygen the ignition of hydrazine (but not its hydrate) takes place at a lower temperature than in air. The ignition temperature is strongly influenced by the material of which the hydrazine container is made. 

The various kinds of pitch used here were carbonized in a porcelain boat within a heated horizontal cylindrical retort. The temperature of the sample, which was measured by means of a thermocouple placed just above the boat, could be maintained constant to within 1°C. All carbonization runs were carried out with an atmosphere of oxygen-free nitrogen. The heated material was cooled to room temperature before examination. 

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