Peroxy group

Sonnerskog [82] found that PVC could oxidize a number of phenols at room temperature in the absence of oxygen. In addition, a graft copolymer was formed when acrylonitrile was added to PVC. These results were taken as indications for the peroxy groups in PVC. 

Frequently, initiators bearing simultaneously azo and peroxy groups were used as bifunctional initiators. 

The activation energies for the decomposition of the the nature of the substituent R and also the number of azo and peroxy groups compiled in Table 4 indicate that CH2-groups (n) between the azo and peroxy group af- Table 4 Azoperoxy initiators ... 

The formation of a polymeric initiator containing azo and peroxy groups has been reported by Hazer et al. [80]. In this paper, poly(ethylene glycol) (M 4 x 10. .. 3 X 10 ) was condensed with AIBN vide ante)... 

Figure 1 Principle of synthesis of block copolymer by the use of macro-initiator. = azo or peroxy group O A = monomer B = oligomer A.

Quantitative analysis of the peroxy group of macroinitiators is performed by iodometry [38] and that of the azo group is done by ultraviolet (UV) spectrometry. Recently, type II MAI composed of PU was determined of its azo concentration by UV [20]. When the UV absorption spectral peak of the azo group overlaps other peaks, DSC is available by determining the azo group from the exothermal peak area [1IJ. 

Peroxides containing more than one peroxy group are also suitable for example ... 

The active enzyme abstracts a hydrogen atom stereospecifically from the intervening methylene group of a PUFA in a rate-limiting step, with the iron being reduced to Fe(II). The enzyme-alkyl radical complex is then oxidized by molecular oxygen to an enzyme-peroxy radical complex under aerobic conditions, before the electron is transferred from the ferrous atom to the peroxy group. Protonation and dissociation from... 

This group of compounds includes those monomers with one or more carbon atoms carrying a hydroperoxy or peroxy group, and also singly bonded to an oxygen atom present as hydroxyl, ether or cyclic ether functions. While the group of compounds is, in general, moderately stable, the lower 1-hydroxy and 1,T-dihydroxy-alkyl peroxides or hydroperoxides are explosive. Individually indexed compounds are ... 

Cyclic allyl peroxides are converted stereoselectively into the dihydroxypropyl peroxides using a modified Sharpless procedure with osmium tetroxide and /-butyl peroxide in the presence of benzyltrimethylammonium acetate [23]. Yields are generally good with exclusive an/f-addition with respect to the peroxy group, although both the steroselectivity and yield (<40%) are poor for the oxidation of 2,3-dihydrofuran-3-yl peroxide and 2,3-dihydro-4//-pyran-4-yl peroxide. 

The gas phase enthalpies of reaction 6 for the variously unsaturated peroxides are also consistent, with one exception. The values are ieri-butyl cumyl peroxide, —288.5 kJmol [l,4-phenylenebis(l-methylethylidene)]bis[(l,l-dimethylethyl) peroxide" (normalized for two peroxy groups), —287.1 kJmol 1,1-dimethylethyl-l-methyl-l-[4-(l-methylethyl)phenyl]ethyl peroxide, —276.6 kJmol and 2-tert-butylperoxy-2-methylhex-5-en-3-yne, —305.8 kJmor. The last species named also has a disparate liquid phase enthalpy of reaction, —344.9 kJ mol . The only solid phase reaction enthalpy, for [l,4-phenylenebis(l-methylethylidene)]bis[(l,l-dimethylethyl) peroxide (normalized for two peroxy groups), is —357.2 kJmol . 

If the double bond in the 7-position to the peroxy group is epoxidized instead as in 155 and 157, cyclization can also be obtained by nucleophilic attack of the OOH group. For example, strongly acidic Amberlyst-15 as reagent gave the desired 1,2-dioxanes 156 and 158 in 65% yield (Scheme 42) <1995JOC3039, 1994TL9429>. 

Radical Polymerization. In this modification, a functional group like an azo or peroxy group, being able to initiate radical polymerization, must be introduced into the particle surface (Scheme 12.1.2). 

Tsubokawa et al. (12-14) have introduced radical sources of azo or peroxy groups by another methods, and successively conducted the radical polymerization of vinyl compounds, such as styrene or methyl methacrylate, to give polymer-grafted particles see Reaction (3). The grafting by the radical polymerization of methyl methacrylate, initiated from a peroxy group introduced on silica, takes place at relatively high efficiency, compared with those from azo group-introduced particles. 

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