Hydroperoxide, irradiated

The photooxidation rates of nylon polymers have been monitored using Fourier Transform Infra-red spectroscopy. Norrish type-II reactions of carbonyl groups were considered to be the most important process. Another group of workers have studied the photooxidations rates of a nylon 6- polypropylene glycol copolymerIn this case polyether sequences are the major source of free radical attack resulting in high levels of hydroperoxides. Irradiation of nylon and polyester fibres with an excimer laser resulted in... 

Solar light may generate sufficient energy to polymeric materials in order to cleave RO-OH and R-OOH bonds in hydroperoxides. So the dissociation energy value of RO-OH bond in hydroperoxides is 176 kJ moF and that of R-OOH is 377 kJ moF [7]. That is why it is considered that during hydroperoxide irradiation the formation of RO- and HO- radicals is predominant. 

Other compounds, eg, azoalkanes, acetone, etc, that yield alkyl radicals either thermally or by uv irradiation have been used with molecular oxygen to prepare alkyl hydroperoxides (r56). 

The hydroperoxide groups thus formed undergo decomposition during irradiation producing macroxy radicals that offer sites for grafting. 

Irradiation of the polymer in air prior to grafting introduces hydroperoxide groups in the backbone polymer by the intermolecular, intramolecular, or hydrogen abstraction process. 

These hydroperoxide groups undergo radiolytic cleavage during irradiation of the aqueous polymer monomer mixture. 

On the basis of the above findings, grafting of vinyl monomers onto irradiated polypropylene has been attempted successfully by the mutual method. Upon irradiation hydroperoxide groups are introduced, which provide sites for grafting. During mutual irradiation in the presence of the monomer in aqueous medium, these hydroperoxide groups and water undergo decomposi-... 

The oxidation of 1,4-dihydronaphthalene with oxygen with irradiation gave l,2-dihydro-2-naphthyl hydroperoxide that decomposed thermally to 3-benzoxepin (3).189... 

Radiation cross-linking of PVC in the absence of additives has been reported by several authors [20,21,267,268]. PVC by itself is not readily cross-linkable by EB radiation. In the study of radiation chemistry of PVC, it is known that the oxidation takes place in the presence of atmospheric oxygen during irradiation [269] and hydroperoxide groups are produced on oxidation. The formation of carbonyl group along with the elimination of HCl from PVC on irradiation in air has also been reported [270,271]. 

The formation of POOH during simultaneous exposure of PP films to ozone and light (LI or L2) can not be obtained kinetically. The experimental results show for rapid formation of hydroperoxide groups which are partially decomposed under UV-irradiation. There is no linear dependence on the ozone concentration. 

From a study of the thermal stability of NOPP (formed by Y-irradiation of 02-free PPH + IbNO-) we have observed the regeneration of I5NO- for films stored in the dark, presumably by reaction 8. However only when tert.-butyl hydroperoxide was diffused into the film did we observe a relatively rapid genera-... 

An interesting multicomponent domino free radical reaction in which five new bonds are formed in one operation has recently been applied in the total synthesis ofyingzhaosu A by Bachi and coworkers. Thus, a 2,3-dioxabicyclo[3.3.1]nonane system reacts with phenylthiol and 2 equiv. of molecular oxygen in the presence of AIBN, which under irradiation with UV light led to a diastereomeric mixture of en-doperoxide-hydroperoxides [127]. 

G. Geuskens, D. Baeyens Volant, G. Delaunois, Q. Lu Vinh, W. Piret, and C. David, Photo oxidation of Polymers II. The Sensitized Decomposition of Hydroperoxides as the Main Path for Initiation of the Photo oxidation of Polystyrene Irradiated at 253.7 nm, Eur. Polym. J., 14, 299 303 (1978). 

Dimethylbenzofurazan 255 was transformed by 02 produced by irradiation of C60 into 4,7-dimethylbenzofur-azan 4,7-endoperoxide 256 in CDCI3 or CD2CI2 at 0°C in excellent yields. The endoperoxide 256 decomposed back to compound 255 at room temperature. When tetramethylethylene (TME) was added to the decomposing endoperoxide 256 at 37 °C, the hydroperoxide from reaction of TME with 02 was detected (Scheme 67) <2001TL987>. 

The equilibrium between 1,1-dimethylethylperoxyl radicals and 1,1-dimethylethyl tetroxide was first evidenced by Bartlett and Guaraldi [157] for peroxyl radicals generated by irradiation of bis( 1,1-dimethylethyl) peroxycarbonate in CH2C12 at 77 K and oxidation of 1,1-dimethylethyl hydroperoxide with lead tetraacetate at 183 K in CH2C12. A series of studies of this equilibrium were performed later using the EPR technique (see Table 2.12). It is seen that the enthalpy of tetroxide decomposition ranges from 29 to 47 kJ mol-1. 

Ohmae and Katsui irradiated vitamin K-l (82) in alcoholic solution with UV light and obtained the hydroperoxide (85), its corresponding hydroxide and the ketone (89). Also isolated were phthiocol (90), the naphthofuran (91) and polymeric material [69], Similar irradiation in benzene gave (89) and (91) [70],... 

Photolytic. Major products reported from the photooxidation of butane with nitrogen oxides under atmospheric conditions were acetaldehyde, formaldehyde, and 2-butanone. Minor products included peroxyacyl nitrates and methyl, ethyl and propyl nitrates, carbon monoxide, and carbon dioxide. Biacetyl, tert-butyl nitrate, ethanol, and acetone were reported as trace products (Altshuller, 1983 Bufalini et al, 1971). The amount of sec-butyl nitrate formed was about twice that of n-butyl nitrate. 2-Butanone was the major photooxidation product with a yield of 37% (Evmorfopoulos and Glavas, 1998). Irradiation of butane in the presence of chlorine yielded carbon monoxide, carbon dioxide, hydroperoxides, peroxyacid, and other carbonyl compounds (Hanst and Gay, 1983). Nitrous acid vapor and butane in a smog chamber were irradiated with UV light. Major oxidation products identified included 2-butanone, acetaldehyde, and butanal. Minor products included peroxyacetyl nitrate, methyl nitrate, and unidentified compounds (Cox et al., 1981). 

Irradiation of toluene in the presence of chlorine yielded benzyl hydroperoxide, benzaldehyde, peroxybenzoic acid, carbon monoxide, carbon dioxide, and other unidentified products (Hanst and Gay, 1983). The photooxidation of toluene in the presence of nitrogen oxides (NO and NO2) yielded small amounts of formaldehyde and traces of acetaldehyde or other low molecular weight carbonyls (Altshuller et al, 1970). Other photooxidation products not previously mentioned include phenol, phthalaldehydes, and benzoyl alcohol (Altshuller, 1983). A carbon dioxide yield of 8.4% was achieved when toluene adsorbed on silica gel was irradiated with light X >290 nm) for 17 h (Freitag et ah, 1985). 

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