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Formation Mills reaction

Silicon Nitride. SiUcon nitride is manufactured either as a powder as a precursor for the production of hot-pressed parts or as self-bonded, reaction-sintered, siUcon nitride parts. a-SiUcon nitride, used in the manufacture of Si N intended for hot pressing, can be obtained by nitriding Si powder in an atmosphere of H2, N2, and NH. Reaction conditions, eg, temperature, time, and atmosphere, have to be controlled closely. Special additions, such as Fe202 to the precursor material, act as catalysts for the formation of predorninately a-Si N. SiUcon nitride is ball-milled to a very fine powder and is purified by acid leaching. SiUcon nitride can be hot pressed to full density by adding 1—5% MgO. [Pg.55]

The ore is ordinarily ground to pass through a ca 1.2-mm (14-mesh) screen, mixed with 8—10 wt % NaCl and other reactants that may be needed, and roasted under oxidising conditions in a multiple-hearth furnace or rotary kiln at 800—850°C for 1—2 h. Temperature control is critical because conversion of vanadium to vanadates slows markedly at ca 800°C, and the formation of Hquid phases at ca 850°C interferes with access of air to the mineral particles. During roasting, a reaction of sodium chloride with hydrous siUcates, which often are present in the ore feed, yields HCl gas. This is scmbbed from the roaster off-gas and neutralized for pollution control, or used in acid-leaching processes at the mill site. [Pg.392]

A strain of Escherichia coli produces a naphthotriazole from 2,3-diaminonaphthalene and nitrite that is formed from nitrate by the action of nitrate reductase. The initial product is NO, which is converted by reactions with oxygen into the active nitrosylating agent that reacts chemically with the amine (Ji and Hollocher 1988). A comparable reaction may plausibly account for the formation of dimethylnitrosamine by Pseudomonas stutzeri during growth with dimethylamine in the presence of nitrite (Mills and Alexander 1976) (Figure 2.2f). [Pg.55]

Heating aluminium powder with carbon tetrachloride, chloromethane or carbon tetrachloride-chloroform mixtures in closed systems to 152°C may cause an explosion, particularly if traces of aluminium chloride are present [1], A mixture of carbon tetrachloride and aluminium powder exploded dining ball-milling [2], and it was later shown that heavy impact would detonate the mixture [3], Mixtures with fluorotrichloroethane and with trichlorotrifluoroethane will flash or spark on heavy impact [4], A virtually unvented aluminium tank containing a 4 1 2 mixture of o-dichlorobenzene, 1,2-dichloroethane and 1,2-dichloropropane exploded violently 7 days after filling. This was attributed to formation of aluminium chloride which catalysed further accelerating attack on the aluminium tank [5], An analysis of the likely course of the Friedel-Crafts reaction and calculation of the likely heat release (29.1 kJ/mol) has been published [26],... [Pg.32]

MnP is the most commonly widespread of the class II peroxidases [72, 73], It catalyzes a PLC -dependent oxidation of Mn2+ to Mn3+. The catalytic cycle is initiated by binding of H2O2 or an organic peroxide to the native ferric enzyme and formation of an iron-peroxide complex the Mn3+ ions finally produced after subsequent electron transfers are stabilized via chelation with organic acids like oxalate, malonate, malate, tartrate or lactate [74], The chelates of Mn3+ with carboxylic acids cause one-electron oxidation of various substrates thus, chelates and carboxylic acids can react with each other to form alkyl radicals, which after several reactions result in the production of other radicals. These final radicals are the source of autocataly tic ally produced peroxides and are used by MnP in the absence of H2O2. The versatile oxidative capacity of MnP is apparently due to the chelated Mn3+ ions, which act as diffusible redox-mediator and attacking, non-specifically, phenolic compounds such as biopolymers, milled wood, humic substances and several xenobiotics [72, 75, 76]. [Pg.143]

Mills and Alexander [4] have discussed the factors affecting the formation of dimethylnitrosamine in samples of soil. Dimethylnitrosamine was formed as readily in sterilized samples as in non-sterile samples, indicating that, although micro organisms can carry out an enzymatic nitrosation in some soils, dimethylnitrosamine can be formed by a non-enzymatic reaction, even at near neutral conditions. The presence of organic matter appears to be important in promoting nitrosation in the presence of the requisite precursors. [Pg.190]

To elucidate the process of the solid-state reaction during ball-milling one has wanted to find out how Y2O3 penetrates into the m-Zr02 lattice and how this results in the formation of a tetragonal Zr02 solid solution (t-Zr02 SS). [Pg.449]


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See also in sourсe #XX -- [ Pg.47 ]




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Mills reaction

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