Effect of Chemical Additives

Some chemical additives can induce ion-radical formation and direct the reaction along the ion-radical route. The effect was discovered and studied in cases of nucleophilic substitutions of cumene derivatives (Kornblum 1975, 1982). Cumyl radicals are formed at the first step of substitution irrespective of whether a dissociative or homolytic cleavage takes place as a result of electron transfer to the cumene derivatives (Zheng et al. 1999). 

As it turned out, the cumyl radical could be trapped not only by those nucleophilic ions, part of which were spent to generate the initial anion-radicals, but also with other anions. Hence, the products of substitution may also be formed with anions that either do not enter into a common reaction with the substrate or react with it slowly. In other words, a very small amount of a reactive nucleophile may induce the reaction. 

Typical one-electron donors, for example, sodium naphthalene, also entrained the reaction of p-nitrocumyl chloride with sodium nitrite (Kornblum et al. 1970). 

It is important to note that sodium methylate initiates only the formation of 4-phenylthio-iso-quinoline the product of the competing substitution, 4-methoxy-iso-quinoline, is produced only in traces. The methylate ion, however, converts a part of the iso-quinolyl a-radicals into the unsubstituted iso-quinoline and produces formaldehyde. 

The first stage of the synthesis involves the interaction of a nitro compound with sodium sulfide. When used alone, sodium sulfide is only slightly effective The reactions proceed slowly and the yields of mercaptanes are small. If elemental sulfur is added, the conversion accelerates markedly and the yield increases to 75-80%. The promoting effect of elemental sulfur can be easily explained by the radical-chain mechanism. The reaction starts with one-electron transfer from the nucleophile to the nitro compound further conversions resemble other chain ion-radical substitutions. 

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The in situ combustion method of enhanced oil recovery through air injection (397,503,504) is an exceeding complex process chemically. However, because little work has been done on the effect of chemical additives to oil recovery efficiency, this process will not be discussed herein. 

The production of olefines from (3-nitrosulfones provides another example of the effect of chemical additives. The reaction is conducted in dimethylformamide without light irradiation. Usually, sodium sulfide is used as a reagent, but the sodium salt of thiophenol may be used instead of sodium sulfide. In the case of Na2S, the olefin forms in 97% yield (Onoetal. 1980,1983) ... 

At the U.S. Forest Products Laboratory, many of the research programs involve fire-retardant-treated wood. This has included extensive basic study of pyrolysis and combustion reactions of wood and its components and the effects of chemical additives on these reactions (15,24-26,28,29,66). A cooperative study (9) with the Division of Chemical Development of the Tennessee Valley Authority, showed the effectiveness of liquid ammonium polyphosphate fertilizers as fire retardants for wood. The commercial use of these products, made from electric furnace superphosphoric acid, has been shown to be economically feasible. Work has been completed by Schaffer (33) on the rate of fire penetration in wood treated with different types of chemicals. Some results of this study are reported elsewhere in this paper. 

Kapsalis, J.G., Betscher, J. J., Kristoffersen, T., Gould, I. A. 1960. Effect of chemical additives on the spreading quality of butter. I. The consistency of butter as determined by mechanical and consumer panel evaluation method. J. Dairy Sci. 43, 1560-1569. 

Goonetilleke PC, Roy D. Electrochemical-mechanical planarization of copper effects of chemical additives on voltage controlled removal of surface layers in electrolytes. Materials Chem Phy 2005 94 388-400. 

EFFECTS OF CHEMICAL ADDITIVES TO OXIDE NITRIDE SELECTIVITY... 

Effect of Chemical Addition In order to insure that surfactants are compatible with the commercial slurries containing chemical reagents, two slurry chemistries (ferric nitrate and hydrogen peroxide) were employed to test the efficiency of the selected surfactants in the presence of chemicals. The results showed that the effect of surfactant on stability and removal rate is not influenced by the presence of the chemicals. Both hydrogen peroxide and ferric nitrate based chemistries were added to Brij 35 based alumina slurries. 

Very few studies have focused on the stability of OAV emulsions in porous media. Sarbar et al. 24) conducted a study to determine the effect of chemical additives on the stability of OAV emulsion flow through porous media. They injected 1, 5, and 10% OAV emulsions in sand packs with varying pH and surfactant concentrations and found that there was an optimal value of the surfactant concentration at which emulsions were the most stable. Addition of sodium chloride to the aqueous phase had a detrimental effect on the stability of the emulsion. For their system they found that there... 

C) (12) The other preservatives were either ineffective or had detrimental effects on flavor, texture, or appearance. Citrus salads were treated with sodium benzoate or potassium sorbate (12). No extension of shelf life was observed when these chemicals were added at storage temperatures of 50°F and 40°F, but when the additives were present at 30°F storage substantial improvements in shelf life were observed, demonstrating the synergistic effect of chemical additives and low temperature storage. 

Krueger, D.J. and Fennema, O.R. 1989. Effect of chemical additives on toughening of fillets of frozen storage Alaska pollack (Theragra chacogramma). Journal of Food Science 54 1101-1106. 

Terrell, J.H. and I. Schmeltz The effect of chemical additives in cigarette tobacco on the composition of... 

Vavrin, F. Effect of chemical additions on hydratation process and hardening of cement. — VI. Internet. Congr. Chem. Cem., Moskau 1974, Sect. 11—6, Principal Paper. 

Table 3.12 Measuring, monitoring and control of wet-end conditions and effectiveness of chemical additives.

Side stream monitoring encompasses the temporary use of a by-pass spool or off-take from the main process stream being monitored to provide supplementary information to that produced by the online monitoring devices. Side stream monitoring may be used to examine the short-term effect of chemical additives or process changes upon the electrochemistry of the plant-material-process-fluid system. 

In order to determine the effect of chemical additives on corrosion, an actual corrosion process must be taking place, so that the inhibitor test and the corrosion test are inseparable. The fact that many variables affect a corrosion process means that numerous different inhibitor tests are available. Although additive concentration is generally low, the type of system, whether once-through or recirculating, or the method of treatment, continuous or batch-wise, will determine, not only the test method, but also the inhibitor concentration required. 

Liu, J. Effects of chemical additives on the light weight paper. Ph.D. thesis, GeOTgia Institute of Technology (2004)... 

Angelova, R. (1997). Effect of Chemical Additives (Including CaCla) on the Strength Development of Soil Cement. Ground Chem. Implic. Constr. Proc. Int. Conf., 147-159. 

In the design of the reactivity control and shutdown systems, account should be taken of the effects of chemical additives on core reactivity (see Ref. [2]). 

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