Chemical reaction adverse

Carbon dio.xide has the adv antages that in use (a) adverse chemical reactions are extremely unhkely, (b) there is no electrical hazard, and (c) damage to apparatus is minimal. 

On the other hand, corrosion has been defined as the undesirable deterioration of a metal or alloy, i.e. an interaction of the metal with its environment that adversely affects those properties of the metal that are to be preserved. This definition —which will be referred to as the deterioration definition —is also applicable to non-metallic materials such as glass, concrete, etc. and embodies the concept that corrosion is always deleterious. However, the restriction of the definition to undesirable chemical reactions of a metal results in anomalies which will become apparent from a consideration of the following examples. 

Control Over Salinity and Adverse Chemical Reactions... 

Certain internal chemical treatments employed also need strict control to avoid risks of adverse chemical reaction and resultant corrosion. In particular, nitrogen-containing chemicals such as hydrazine and amines require effective monitoring to limit the concentration of ammonia release into steam because the presence of ammonia may, under certain conditions, cause stress corrosion cracking of copper and brasses. 

This tendency to interact with -SH groups appears to be the fundamental chemical reaction behind most of the adverse biochemical effects of organomercury compounds it is also the basis for one mechanism of detoxication. 

In addition, the formation of terminal metabolites may be adverse either for the organism itself, or for other organisms in the ecosystem. Microbial metabolites may also undergo purely chemical reactions to compounds that are terminal products. Examples include the formation of 5-hydroxyquinoline-2-carboxylate from 5-aminonaphthalene-2-sulfonate (Nortemann et al. 1993) or benzo[fc]naphtho[l,2- /]thiophene from benzothiophene (Kropp et al. 1994). Microbial metabolites may be toxic to both the bacteria producing them and to higher organisms. Illustrative examples of toxicity include the following ... 

Control of exudation depends mainly on the suitable choice of the nitrocellulose used. Some lack of uniformity in this product is certainly desirable. This offers no serious difficulty, although it is necessary to ensure a constant watch on manufacturing processes to see that quality is maintained. In other gelatine explosives, particularly those containing ammonium nitrate, exudation can be induced by slow chemical reaction. The addition of alkalis, for example, can liberate ammonia which in turn can react with nitrocellulose and cause it to lose its power of binding nitroglycerine. Such effects are accelerated at high temperatures and under wet conditions and it is usual practice to test all explosives under such adverse conditions before they are put on the market. 

Some organochlorine, organophosphorus, and carbamate insecticides used after World War II (since 1945) were found to have various problems of adverse effects on mammals and environmental behavior and influences. The use of many industrial chemicals has been prohibited because those contained as impurities in minute quantities produced critical toxic substances by transformation and repeated chemical reactions in their environment. 

In some absorption processes, especially where a chemical reaction occurs, there is a liberation of heat. This generally gives rise to an increase in the temperature of the liquid, with the result that the position of the equilibrium curve is adversely affected. 

The best correlations were obtained with the values of a- constants generally applied to correlating chemical reactions which involve the phenolic oxygen.89 It is typical of the adverse influence of substituents that Eqs. (1) and (2) are significantly different in p values. The two nitro derivatives in both do not lie on the correlation lines. It was found that nitro-substituted aryl esters preferentially undergo alcoholysis and reduction.70... 

This cascade however may be propagated throughout the cell unless terminated by a protective mechanism (see below) or a chemical reaction such as disproportionation, which gives rise to a non-radical product. Polyunsaturated fatty acids, found particularly in membranes, are especially susceptible to free radical attack. The effects of lipid peroxidation are many and various. Clearly, the structural integrity of membrane lipids will be adversely affected. In the lipid radical produced, the sites of unsaturation may change, thereby altering the fluidity of the membrane (see chap. 3). Lipid radicals may interact with other lipids and... 

Chemical Reaction Mechanisms and Kinetics. CVD chemistry is complex, involving both gas-phase and surface reactions. The role of gas-phase reactions expands with increasing temperature and partial pressure of the reactants. At high reactant concentrations, gas-phase reactions may eventually lead to gas-phase nucleation that is detrimental to thin-film growth. The initial steps of gas-phase nucleation are not understood for CVD systems, not even for the nucleation of Si from silane, which has a potential application in bulk Si production (97). In addition to producing film precursors, gas-phase reactions can have adverse effects by forming species that are potential impurity sources. 

This purification process is quite sensitive to pH (Ref 23). As shown in Fig 6, yield loss rises sharply above pH 7.5, because of the formation of the water-soluble complex of 2,4,6-TNT with Na sulfite. In addition, at pH values above about 8 (see Fig 7 and Table 1), the formation of two by-products [hexanitrobibenzyl (HNBB), and methylpentanitrodiphenylme thane (MFDM)] increases strongly. (The chemical structures and modes of formation of these compds are given in the section on Chemical Reactions and Derivatives ). These compds have an adverse effect on the mode of crystn of TNT, resulting in the formation of cracks and voids in the finished cast expl (Ref 13). It is also apparent from Table 1 that meta TNT isomers are not completely removed, and that the amounts of all of the DNT Isomers and of five of the oxidation products remain unchanged... 

With regard to application and construction, it is convenient to differentiate between fixed-bed reactors for adiabatic operation and those for nonadiabatic operation. Since temperature control is one of the most important methods to influence a chemical reaction, adiabatic reactors are used only where the heat of reaction is small, or where there is only one major reaction pathway in these cases no adverse effects on selectivity or yield due to the adiabatic temperature development are expected. The characteristic feature of an adiabatic reactor is that the catalyst is present in the form of a uniform fixed bed that is surrounded by an outer insulating jacket (Fig. 1A). Adiabatic reactor designs are discussed in Section 10.1.3.1. 

As used in this report, the term environmentally acceptable implies a high probability that the carbon will not leak into the atmosphere during processing and handling, that it will remain sequestered from the atmosphere essentially in perpetuity, and that it will not cause adverse side effects, such as harmful chemical reactions, while so sequestered. 

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