Poly hydroperoxide

The acetone supply is strongly influenced by the production of phenol, and so the small difference between total demand and the acetone suppHed by the cumene oxidation process is made up from other sources. The largest use for acetone is in solvents although increasing amounts ate used to make bisphenol A [80-05-7] and methyl methacrylate [80-62-6]. a-Methylstyrene [98-83-9] is produced in controlled quantities from the cleavage of cumene hydroperoxide, or it can be made directly by the dehydrogenation of cumene. About 2% of the cumene produced in 1987 went to a-methylstyrene manufacture for use in poly (a-methylstyrene) and as an ingredient that imparts heat-resistant quaUties to polystyrene plastics. 

Hydroperoxides Organomineral Hydroperoxides a-Oxy and a-Peroxy-Hydroperoxides and Peroxides Ozonides Peroxides Peroxy Acids Diacyl Peroxides Peroxy Esters and Poly Peroxides... 

Poly(hydrosilane)s are stable compounds and can be manipulated in the air only for a short period since they are oxygen-sensitive. The oxidized products obtained from poly(phenylhydrosilane) exposed to the air contain the units 119-122 without the formation of silyl hydroperoxides and peroxides. In particular, units 119,120, and 121+122 were present in the relative percentages of 27,54, and 19%, respectively, which means that more than 70% of the catenated silicons are altered. 

Depending on the nature of the sulfur or phosphorus compound used, the product R2S = O or R3P = O may undergo a number of further reactions with ROOH groups, all of which convert the hydroperoxide group into an alcohol. These compounds tend to be only weakly effective so are generally used in conjunction with synergistic promoters. Suitable mixtures are used to stabilise a variety of polymers including poly(alkenes), ABS, and poly(stryrene). 

In the field of free radicals and liver injury there is a vast body of work concerning a group of compounds that have proven to be of great value as experimental models but are of little clinical significance. The most frequently used compounds are quinones (particularly menadione), paraquat and diquat, bromobenzene, and organic hydroperoxides, particularly cumene hydroperoxide and r-butyl hydroperoxide (see Poli et al., 1989b). 

Syntheses. The polymerization reaction of poly(2-methyl pentene-1 sulfone) (PMPS) was carried out at -78°C. Purified 2-methyl pentene-1 (42 grams) and condensed SO, (about 125 grams) at a molar ratio of 1 to 4 were charged into the reaction system under atmospheric pressure, and the reaction was Initiated by 2 milliliters of butyl hydroperoxide. The white polymer mass was purified by dissolving 1n acetone, then precipitating Into methanol (8). 

Allen, N. S., Edge, M., Mohammadian, M. and Jones, K., UV and thermal hydrolytic degradation of poly (ethylene terephthalate) importance of hydroperoxides and benzophenone end groups, Polym. Degrad. Stabil., 41, 191-196 (1993). 

Figure 18.13 Effect of fluorescent device exposure on hydroperoxide production in Spectar copolymer [11]. Reprinted from Polymer, 41, Grossetete, T., Riva-ton. A., Gardette, J.-L., Hoyle, C. E., Ziemer, M., Fagerburg, D. R. and Clauberg, H., Photochemical degradation of poly(ethylene terephthalate)-modified copolymer, 3541-3554, Copyright (2000), with permission from Elsevier Science...

It should additionally be noted that a number of the paths of the schemes above have received some confirmation in a number of literature reports dealing with the photolysis and photo-oxidation of other polyesters [32-35], Because these reports investigated poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) and poly(butylene naphthalate), however, they may not have direct application to understanding of the processes involved in PET and PECT and so have not been discussed in this present chapter. All do contain support for the formation of radicals leading to CO and C02 evolution, as well as the hydrogen abstraction at glycolic carbons to form hydroperoxides which then decompose to form alkoxy radicals and the hydroxyl radical. These species then were postulated to undergo further reaction consistent with what we have proposed above. 

One of the first attempts to extend polymer-assisted epoxidations to asymmetric variants were disclosed by Sherrington et al. The group employed chiral poly(tartrate ester) hgands in Sharpless epoxidations utilizing Ti(OiPr)4 and tBuOOH. However, yields and degree of stereoselection were only moderate [76]. In contrast to most concepts, Pu and coworkers applied chiral polymers, namely polymeric binaphthyl zinc to effect the asymmetric epoxidation of a,/9-unsaturated ketones in the presence of terPbutyl hydroperoxide (Scheme 4.11). 

Poly(hydrosilane)s are stable compounds and can be manipulated in the air only for a short period since they are oxygen sensitive. In order to study the oxidation products, a xylene solution of poly(phenylhydrosilane)(Mw = 2340, Mw/Mn = 1.72) was refluxed (140 °C) for 12 h in a system exposed to the air [15]. Only minor changes were observed by GPC analysis whereas FTIR showed characteristic absorptions due to siloxane-type structures on the polymer backbone. A detailed NMR analysis, based on H NMR, Si INEPT and H- Si HMQC spectroscopies, indicated that the oxidized material contains the units 7-10 shown in Scheme 8.2. In particular, units 7,8 and 9+10 were present in relative percentages of 27%, 54% and 19%, respectively, which mean that more than 70% of the catenated silicons were altered. It has also been reported that silyl hydroperoxides and peroxides are not found as products in the autoxidation of poly(phenylhy-drosilane) [16]. 

Different initiators have varying transfer constants (Table 3-5). Further, the value of C) for a particular initiator also varies with the reactivity of the propagating radical. Thus there is a fivefold difference in C) for cumyl hydroperoxide toward poly(methyl methacrylate) radical compared to polystyryl radical. The latter is the less reactive radical see Sec. 6-3b. 

Polymer immobilization. Mo-peroxide, 427 Polymerization agents, 621, 622 peroxide value, 661, 662 peroxycarboxyUc acids, 698 radical polymerization, 697, 707 styrene, 697, 720 sulfonyl peroxides, 1005 thermochemistry, 155 Polymers aging, 685 autoxidation, 623 hydroperoxide determination, 685 Poly(methacrylonitrile peroxide)... 

Poly(vinylferrocenium perchlorate). Hydroperoxide biosensor, 688 POM (polyoxometaUates), 429-30, 1057 POP (persistent organic pollutants), 747 Poppyseed oil, vibrational spectra, 692 Porphyrin, O NMR spectroscopy, 185 Potassium carbonate, alcohol oxidation, 492 Potassium hexacyanoferrate(II), hydrogen peroxide biosensor, 653 Potassium hydrogen phthalate hemiperhydrate, 98-100... 

Materials. Poly (olefin sulfone)s were prepared by copolymerization of liquid mixtures of sulfur dioxide and the appropriate olefin using tert.-butyl hydroperoxide as initiator in the temperature range from —80 to 0°C. The poly (amino acid)s were obtained from Sigma Chemical Co. and used without further purification. The poly (olefin) s were provided by Mr. O. Delatycki and Dr. T. N. Bowmer and were prepared under controlled conditions. The aromatic polysulfones were prepared and purified by Mr. J. Hedrick. The purity of all polymers was checked by H and 13C NMR. 

A polymer-supported Sharpless epoxidation catalyst was prepared using linear poly(tartrate ester) catalyst ligands 43.65 This catalyst system was used in the reaction of tranA-hex-2-en- l-ol with titanium tc/ra-isopropoxide and tert-butyl hydroperoxide to afford the desired epoxide in high chemical yield and moderate enantiomeric excess. 

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