Hydroperoxides peroxides

The type of initiator utilized for a solution polymerization depends on several factors, including the solubiUty of the initiator, the rate of decomposition of the initiator, and the intended use of the polymeric product. The amount of initiator used may vary from a few hundredths to several percent of the monomer weight. As the amount of initiator is decreased, the molecular weight of the polymer is increased as a result of initiating fewer polymer chains per unit weight of monomer, and thus the initiator concentration is often used to control molecular weight. Organic peroxides, hydroperoxides, and azo compounds are the initiators of choice for the preparations of most acryUc solution polymers and copolymers. 

Synthesis. Dialkyl peroxides are prepared by the reaction of various substrates with hydrogen peroxide, hydroperoxides, or oxygen (69). They also have been obtained from reactions with other organic peroxides. For example, dialkyl peroxides have been prepared by the reaction of hydrogen peroxide and alkyl hydroperoxides with alMating agents, eg, RX and olefins (33,66,97) (eqs. 24—27). 

Free radical initiators can polymerize olefmic compounds. These chemical compounds have a weak covalent bond that breaks easily into two free radicals when subjected to heat. Peroxides, hydroperoxides and azo compounds are commonly used. For example, heating peroxybenzoic acid forms two free radicals, which can initiate the polymerization reaction ... 

Peroxides, hydroperoxides [1, 2] e.g. (photo)-axidation products of limonene [3]... 

Thermal decomposition of dialkyl peroxides, diacyl peroxides, hydroperoxides and peracids depending on the structure of the peroxidic compound occurs in a measurable rate usually above 60°C. Diacyl peroxides and peracids are considerably less stable than dialkyl peroxides and hydroperoxides. 

Oxygen-oxygen bonds (peroxides, hydroperoxides, ozonides)... 

The peroxide value measurement is a general quantitative measure of peroxide/hydroperoxide intermediates produced during oxidative degradation. 

Inorganic and organic peroxo compounds, e.g., peroxodisulfates, peroxides, hydroperoxides, peresters Protic acids Proton acceptors Organometallic compounds... 

Hydrogen peroxide Peroxodisulfates Diacyl peroxides Hydroperoxides Peracid ester Ag+,Fe2+,Co +,Tp+ Hydrogen sulfites, sulfites, thiosulfates, mercaptans, sulfinic acids Amines (e.g. NdV-dimethylaniline), certain sugars Benzoin/Fe Hydrogen sulfite/Fe ... 

Bromopyrogallol Red, hydrogen peroxide determination, 628-9 Bronchial epithehal cells, IR spectrophotometry, 683 Br0nsted acids, olefin epoxidation, 471 BSA see Bovine semm albumin BTSP see Bis(trimethylsilyl) peroxide 2-Butanone peroxide, hydroperoxide determination, 686, 688, 689 -2-Butene, final ozonide, 721 t-Butoxy free radical, a-methylstyrene dimer reaction, 697... 

The most common initiators are acyl peroxides, hydroperoxides, or azo compounds. Hydrogen peroxide, potassium persulfate, and sodium perborate are popular in aqueous systems. Ferrous ion in some cases enhances the catalytic effectiveness. 

Oxidations are catalyzed by acids, bases, pH values that are higher than the optimum, polyvalent metal ions, peroxides, hydroperoxides, and exposure to oxygen and ultraviolet (UV) illumination. These reactions may necessitate the use of antioxidant chemicals, inert atmospheres, and opaque packaging. Chelating agents... 

Two fluorescent probes dihydroethidium (DHE) and dichlorodihydrofluorescein (DCFH) are used for superoxide detection in biological systems [54]. Both assays are subjected to some drawbacks such as the oxidation of cytochrome c, the dismutation of superoxide in the presence of DHE [79], and the interaction of DCFH with hydrogen peroxide, hydroperoxides, or peroxynitrite. Particularly big enhancement of DCF formation due to the oxidation of cytochrome c is observed when cytochrome is released from mitochondria during cell death... 

The catalytic or initiated reaction involves heating the poly(diene) in an aromatic solvent to temperatures between 120-150 °C in the presence of free radical initiators such as peroxides, hydroperoxides and azo compounds. The ensuing reaction involves addition of maleic anhydride to a polymeric radical which was formed by abstraction of an allylic hydrogen by initiator radicals. Four modes of addition are possible leading to partial structures such as (175)-(178) illustrated with poly(isoprene). It can readily be seen that some crosslinking is an inherent problem because of structures (177) and (178). The amount of gel formed, however, is found to be largely dependent on the initiator employed and can be minimized, especially with hydroperoxide initiators. 

The oxygen atom reacts with 02 to produce ozone. Both O and 03 react with organic materials to produce peroxides, hydroperoxides, aldehydes, and other toxic substances. An excellent review of the photochemistry of air pollution has been given by Leighton.278... 

Synthesis. Dialkyl peroxides are prepared by the reaction of various substrates with hydrogen peroxide, hydroperoxides, 01 oxygeu. They also have been obtained from reactions with other organic peroxides. 

The most commonly used catalysts are peroxides, hydroperoxides and aliphatic azocompounds, which need activation energies between 25 and 30 kcal for decomposition. 

PEROXIDES, HYDROPEROXIDES, and PERACIDS PHENOLS, see HYDROXYL COMPOUNDS... 

Benson SW, Shaw R (1970) Thermochemistry of organic peroxides, hydroperoxides, polyoxides, and their radicals. In Swern D (ed) Organic peroxides, vol I. Wiley, New York, pp 105-139 Berdnikov VM, Bazhin NM, Fedorov VK, Polyakov OV (1972) Isomerization of the ethoxyl radical to thea-hydroxyethyl radical in aqueous solution. KinetCatal (EngITransI) 13 986-987 Besler BH, Sevilla MD, MacNeille P (1986) Ab initio studies of hydrocarbon peroxyl radicals. J Phys Chem 90 6446-6451... 

Organic peroxides acyl peroxides (benzoyl, acetyl, lauryl peroxides, etc), alkyl peroxides, hydroperoxides, etc. are used as polymerization initiators. Azocompounds (for example, redox systems, etc. are also widely used as initiators. In... 

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