With air

Exposure of neat dialkyl tellurium compounds or their solutions to air or pure oxygen led to the formation of dialkyl tellurium oxides. Diphenyl tellurium dissolved in diethyl ether is only slowly oxidized by oxygen.  

Bisltrifluoromethyl] Tellurium Oxide A 10% solution of bis[trifluoromethyl] tellurium in fluorotri-chloromethane is prepared and oxygen is passed through the solution at 20° until it is decolorized. The product precipitates as a white, stable solid that does not melt up to 350°. 

The following eompounds were prepared using air as oxidant  

These reactors were the first ones used and are still today a fairly common way of carrying out oxidation in refineries. In contrast, replacing air with oxygen is much more recent. With the 8203 stage as the limit, cocurrent oxidation towers in the United States are often designed for the following conditions  

There is no addition of catalyst, but steam make up instead to hold the temperature to the required level. 

Oxidation to the SO stage is seldom carried out completely, but when it is the following conditions prevail in pressurized reactors  

API (Liquid Waste, 1969, Chapter 11, Section 1.7) gives a design example for a cocufrent column, with the same aim of reaching only 8203 (Fig. 50)  

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Flash point. The flash point of a liquid is the lowest temperature at which it gives off enough vapor to form an ignitable mixture with air. The flash point generally increases with increasing pressure. 

Chamber B is filled with partially degassed sample material at 0°C. Chamber A is filled with air at 37.8°C and at atmospheric pressure. 

The flash point measures the tendency of a petroleum material to form a flammable mixture with air. It is one of the properties to be considered when evaluating the flammability of a petroleum cut. 

For olefins, the limits are greater by about 30%. At ambient temperatures, heavy materials have a vapor pressure too low to cause an explosive mixture with air. 

The maximum power is available with air cooling up to 45kV for insulation reasons, the tubes are downrated to about 20W at 65kV. 

Introscopic image(left) and tomogramm (right) of rod fuel element with air pore... 

Attenuation is also an important factor in air-bome ultrasound. For exampe, attenuation in air at 1 MHz is 1.2 dB/cm, compared with a figure of 0.0022 dB/cm in water [1]. In addition, environmental conditions (temperature, turbulences) can affect the inspection with air-bome... 

The pulser/receiver HILL-SCAN 30XX boards satisfy DIN 25450. Typical applications are ultrasonie imaging systems for nuclear power stations and for aircraft, material characterization, transducer qualification, replacement of portable flaw detectors (inspections of welded joints), inspection of new materials, measurement systems with air eoupling. ... 

Laser Raman diagnostic teclmiques offer remote, nonintnisive, nonperturbing measurements with high spatial and temporal resolution [158], This is particularly advantageous in the area of combustion chemistry. Physical probes for temperature and concentration measurements can be debatable in many combustion systems, such as furnaces, internal combustors etc., since they may disturb the medium or, even worse, not withstand the hostile enviromnents [159]. Laser Raman techniques are employed since two of the dominant molecules associated with air-fed combustion are O2 and N2. Flomonuclear diatomic molecules unable to have a nuclear coordinate-dependent dipole moment caimot be diagnosed by infrared spectroscopy. Other combustion species include CFl, CO2, FI2O and FI2 [160]. These molecules are probed by Raman spectroscopy to detenuine the temperature profile and species concentration m various combustion processes. 

Before this treatment, the cassiterite content of the ore is increased by removing impurities such as clay, by washing and by roasting which drives off oxides of arsenic and sulphur. The crude tin obtained is often contaminated with iron and other metals. It is, therefore, remelted on an inclined hearth the easily fusible tin melts away, leaving behind the less fusible impurities. The molten tin is finally stirred to bring it into intimate contact with air. Any remaining metal impurities are thereby oxidised to form a scum tin dross ) on the surface and this can be skimmed off Very pure tin can be obtained by zone refining. 

White phosphorus is very reactive. It has an appreciable vapour pressure at room temperature and inflames in dry air at about 320 K or at even lower temperatures if finely divided. In air at room temperature it emits a faint green light called phosphorescence the reaction occurring is a complex oxidation process, but this happens only at certain partial pressures of oxygen. It is necessary, therefore, to store white phosphorus under water, unlike the less reactive red and black allotropes which do not react with air at room temperature. Both red and black phosphorus burn to form oxides when heated in air, the red form igniting at temperatures exceeding 600 K,... 

Large quantities of sulphur are recovered from petroleum and natural gas. Naturally occurring hydrogen sulphide, HjS, and that produced in the cracking and catalytic hydrogenation of petroleum is first removed by absorption and the regenerated gas is converted to sulphur by partial combustion with air, the overall reaction being,... 

However, hydrogen chloride gas, obtained as a by-product in chlorination reactions, is commercially converted to chlorine by passing the hydrogen chloride mixed with air over a copper catalyst at a temperature of 600-670K when the following reaction occurs ... 

By the oxidation of hydrogen chloride. A mixture of hydrogen chloride with air or oxygen is passed over a catalyst of copper(II)... 

The common ores of zinc are zinc blende, ZnS, and calamine, ZnC03. The metal is extracted (a) by roasting blende with air or by heating... 

Carbon disulphide should never be used if any alternative solvent is available, as it has a dangerously low flash-point, and its vapours form exceedingly explosive mixtures with air. Ether as a solvent for recrystallisation is much safer than carbon disulphide, but again should be avoided whenever possible, partly on account of the danger of fires, and partly because the filtered solution tends to creep up the walls of the containing vessel and there deposit solid matter by complete evaporation instead of preferential crystallisation. 

Before use, the marble chips are washed repeatedly with hot water, and then de-aerated by first etching them with concentrated hydrochloric acid and then boiling them with air-free water under reduced pressure. The chips are then rapidly transferred to the generator small chips should be used and the bulb... 

Place 5 ml. of milk in each of two test-tubes A and B. Boil the milk in B thoroughly for 2 minutes to destroy the enzyme, and cool. Then in each test-tube place i ml. of the acetaldehyde solution and i ml of the methylene-blue solution. Mix gently by inverting the tubes avoid shaking with air. Now place A and B in a water-bath maintained at 40-50. After a time (usually about 20 minutes) the dye in A is completely decolorised except at the surface, while B is unaffected. 

Substances which decompose (or otherwise change) in contact with air must be recrystallised in an indifferent atmosphere, such as carbon dioxide, nitrogen or hydrogen. The apparatus of Fig. 

This preparation is an example of the use of di-M-butyl ether as a solvent in the Grignard reaction. The advantages are it is comparatively inexpensive, it can be handled without excessive loss due to evaporation, simple distillation gives an ether free from moisture and alcohol, and the vapour does not form explosive mixtures with air. n-Butyl ether cannot, of course, be employed when the boiling point of the neutral reaction product is close to 140°. 

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