Peroxides types

Bleaches of the simple ammoniacal peroxide type give limited lightening, which can be increased with bleach accelerators or boosters, including one or more per salts such as ammonium, potassium, or sodium persulfate or their combinations. These salts, which are susceptible to decomposition in aqueous solution, are packaged as dry powders and added just before use. In the absence of hydrogen peroxide, however, persulfates do not have any bleaching effect (41). 

Because high temperatures are required to decompose diaLkyl peroxides at useful rates, P-scission of the resulting alkoxy radicals is more rapid and more extensive than for most other peroxide types. When methyl radicals are produced from alkoxy radicals, the diaLkyl peroxide precursors are very good initiators for cross-linking, grafting, and degradation reactions. When higher alkyl radicals such as ethyl radicals are produced, the diaLkyl peroxides are useful in vinyl monomer polymerizations. 

Random copolymer—Distribution of the monomer units does not follow any definite sequence. These are produced in bulk, aqueous, suspension, or emulsion using free radical initiators of the peroxide type or redox systems. 

Apart from peroxide types and amount of peroxide incorporated in compounds, the efficiency of cross-linking depends on co-agents. The commercially notably ones are... 

Needless to say, there is a definite possibility that, if reactions as just described participate in the transformations of polyuronide polysaccharides, enzymatic control of these may exist by systems leading to the oxidation of ascorbic acid or producing peroxide-type intermediaries. 

Work on the deflagration hazards of organic peroxides has been done using a revised Time-Pressure test, to determine the characteristics of ignition sensitivity and violence of deflagration. Some correlation is evident between these characteristics and the AO content within each structurally based peroxide type. Also, for the same AO content, the nature of the characteristics appears to decrease hi the order diacyl peroxides, peroxyesters, dialkyl peroxides, alkylhydroperoxides [18],... 

In conclusion, it is noted that, as an empirical rule, first row transition metal elements generally form superoxide-type dioxygen complexes, whereas elements of the second and third transition series form peroxide-type dioxygen complexes. 

The polymerization initiator is an organic peroxide type. Particular examples of the organic peroxides are shown in Table 4.3. The polymerization initiator is used in an amount of usually about 0.01-1% of the polymer. 

The compound H2SO, which is assumed to be of the peroxide type, decomposes with precipitation of sulphur. The hydrogen sulphide also reacts further with the sulphoxylie acid primarily formed to yield more H2SO ... 

Prices of commercial organic peroxides range from ca 2.50 to > 35/kg. depending on peroxide type, production volume, assay, nature of formulation. cost of raw materials, and degree of special processing and handling requirements. 

Vulcanization by sulfur accounts for practically all the commercial products. However, peroxide types of curing systems may be used, especially for some of the synthetic rubbers. 

Another aspect of LOX regards its specificity of product formation. The peroxidative-type LOX mentioned above tends to form a signifi-... 

On ceria, unreduced gold seems to play a major role in the reaction (Section 6.3.3.6). Ceria may provide sites for the formation of superoxide and peroxide-type species,100 or act as an oxygen supplier for a reaction of Mars and van Krevelen-type.97 It is occasionally suggested that the reaction might go entirely on the support itself modified by gold ions, and forming a solid solution of type Cei a Au3 02 5-98... 

This adsorbed oxygen can then migrate across the surface or into the interior of the coal particle to a reactive site at which point it becomes chemically bound. The form of this chemical bond is phenolic-OH, carbonyl or peroxide type moieties. As the surface layers become saturated, the oxygen will diffuse deeper into the particles through pores and crevices to react with sites within the coal particle. This is the second, slower part of the adsorption process. At some point the chemical potential against diffusion into the particle becomes great enough that the oxidation from the exterior of the particle ceases. This point will be determined by the porosity of the coal and the temperature at which the oxidation is carried out. As... 

In all four cases, the two regioisomeric allylic hydroperoxides are formed with identical diastereomeric ratios, clearly indicating a common symmetrical intermediate, presumably of the cyclic peroxide type. The relative configurations [(R, R )/(R, S )] of the photooxygenation products were not determined. 

Elastomers must be crosslinked to hold their final form. The crosslinking reaction takes place through generation of free radicals that promote bonding at sites of unsaturation. The most common crosslinking agents for this include reactive peroxides, such as dicumyl peroxide, diacetyl peroxide, di-tert butyl peroxide, and others. Since each has a different temperature at which thermal decomposition initiates, curing conditions vary with the peroxide type. 

Polymerization techniques may be (1) in the gas phase at high pressures and temperatures (200C), (2) in solution at normal pressure and temperatures from -70 to +70C, (3) bulk or batch polymerization at normal pressure at 150C, (4) in suspension at normal pressure at 60-80C, (5) in emulsion form at normal pressure at -20 to +60C (used for copolymers). Catalysts of the peroxide type are necessary with some of these methods. 

Furthermore, it has been assumed that two crypto-hydroxyl radicals located at neighboring storage places lead by interaction to the preformation of an O-O-bond of peroxide type, complexed via two manganese centers. Hence, this state represents a binuclear complexed cryptoperoxide . 

The definitions applied to organic peroxide formulation behavior can be subject to interpretation. Therefore, in an effort to better identify commercial organic peroxide formulations by class, a listing of typical formulations and their classes can be found in the Appendix of NFPA 43B. This listing includes the name and concentration of the organic peroxide, type of diluent, maximum individual container size and the NFPA 704 hazard identification rating. 

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