Nitrogen ambient temperature

The nitrogenase system reduces hundreds of millions of kilograms of nitrogen gas to ammonia each year, catalysing tire reaction at ambient temperatures and atmospheric pressure. Nitrogenase consists of two proteins tliat contain... 

To be specific let us have in mind a picture of a porous catalyst pellet as an assembly of powder particles compacted into a rigid structure which is seamed by a system of pores, comprising the spaces between adjacent particles. Such a pore network would be expected to be thoroughly cross-linked on the scale of the powder particles. It is useful to have some quantitative idea of the sizes of various features of the catalyst structur< so let us take the powder particles to be of the order of 50p, in diameter. Then it is unlikely that the macropore effective diameters are much less than 10,000 X, while the mean free path at atmospheric pressure and ambient temperature, even for small molecules such as nitrogen, does not exceed... 

Coal tar is the condensation product obtained by cooling to approximately ambient temperature, the gas evolved in the destmctive distillation of coal. It is a black viscous Hquid denser than water and composed primarily of a complex mixture of condensed ring aromatic hydrocarbons. It may contain phenoHc compounds, aromatic nitrogen bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons. Coal-tar pitch is the residue from the distillation of coal tar. It is a black soHd having a softening point of 30—180°C (86—359°F). 

At ambient temperatures beryUium is quite resistant to oxidation highly poHshed surfaces retain the brilliance for years. At 700°C oxidation becomes noticeable in the form of interference films, but is slow enough to permit the working of bare beryUium in air at 780°C. Above 850°C oxidation is rapid to a loosely adherent white oxide. The oxidation rate at 700°C is paraboHc but may become linear at this temperature after 24—48 hours of exposure. In the presence of moisture this breakaway oxidation occurs more rapidly and more extensively. BeryUium oxide [1304-56-9] BeO, forms rather than beryUium nitride [1304-54-7] Be2N2, but in the absence of oxygen, nitrogen attacks beryUium above 900°C. 

Catastrophic failure of containers as cryogen evaporates to cause pressure build-up within the vessel beyond its safe working pressure (e.g. pressures <280 000 kPa or 40 600 psi can develop when liquid nitrogen is heated to ambient temperature in a confined space). 

Nitric oxide combines readily with atmospheric oxygen at ambient temperature to produce brown fumes of pungent nitrogen dioxide, and in the presence of charcoal with chlorine to form nitrosyl chloride ... 

The oxygen is then replaced by nitrogen and a solution of sodium hydroxide (5 g) in methanol (100 ml) and water (50 ml) is added. After agitation for 70 min at ambient temperature, followed by the addition of acetic acid (10 ml), the mixture is poured into water (4 liters). The precipitate is isolated by filtration, washed with water and dried in an air draft at 100° to yield 47 g of crude product. This material is dissolved in methanol (1.5 liters) and ethyl acetate (500 ml) and the solution concentrated to half its initial volume. Ethyl acetate (500 ml) is added and the solution is cooled to yield 29.4 g (63%) of 3, 17a-dihydroxy-16f -methyl-5a-pregnan-20-one mp 255-260° [ajp 45.6° (diox.). 

Use Figure 9.2 (equal to Figure 6.19 from Section 6.3.3) to select the appropriate calculation method. The only information needed for selection of a method is the phase of the fluid. Nitrogen at ambient temperature can be regarded as an ideal gas at these pressures. Therefore, the basic method (Section 6.3.3) is used. 

A suspension of 13.2 g methyl 3-(p-chlorobenzoyl)-3-thioacetylpropionate is agitated in 500 ml of a 2N aqueous solution of KOH for 6 hours at ambient temperature in an atmosphere of nitrogen, followed by extraction with ethyl ether. The aqueous phase, adjusted to a pH equal to 2 with 2N HCI, is extracted with ethyl ether which was washed with water, dried over Na2S04, and finally evaporated to dryness. 

The metal catalyst is not absolutely required for the aziridination reaction, and other positive nitrogen sources may also be used. After some years of optimization of the reactions of alkenes with positive nitrogen sources in the presence of bromine equivalents, Sharpless et al. reported the utility of chloramine-T in alkene aziridinations [24]. Electron-rich or electron-neutral alkenes react with the anhydrous chloramines and phenyltrimethylammonium tribromide in acetonitrile at ambient temperature, with allylic alcohols being particularly good substrates for the reaction (Schemes 4.18 and 4.19). 

Materials compatibility. We use scrupulously clean and scratch-free FEP (FEP is the acronym for the copolymer of tetrafluoroethylene and hexafluoropropylene) tubing for handling our mixtures of fluorine and nitrogen at ambient temperature. Corrugated FEP tubing is convenient for making strain-free assemblies. We have found that Monel is excellent for use with dry molten KF-2HF. Mild steel corrodes slowly and stainless steels corrode rapidly. Kel-F polychlorotrifluoroethylene is satisfactory for use with HF and with KF-2HF polypropylene and polymethylpentene are not satisfactory. 

In which 100 cc could be polymerized. We used a pressure gage, rated from 0 to 140 pounds per square Inch. There were 3 type J thermocouples - one In the center of the solution, one In the reactor wall, and the third near the heater outside the reactor. The experiments were conducted In a high pressure bay and observed on closed circuit television. The Initial polymer concentrations of the test reactants were either 0 or 15 or 30 percent by weight. An electric heater controlled the ambient temperature of the nitrogen - purged reactor, and supplied heat to Initiate the reaction. 

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