Peroxide function

Very selective c/s-hydrogenations are also achieved by reduction with diiminc (N2H2, S. Hiinig, 1965 C.E. Miller, 1965 D.J. Pasto, 1991). The reagent can be used at low temperatures and has been employed in the selective reduction of C C double bonds, e.g. in the presence of a sensitive peroxidic function (W. Adam, 1978). 

The multifunctional initiators may be di- and tri-, azo- or peroxy-compounds of defined structure (c.g. 20256) or they may be polymeric azo- or peroxy-compounds where the radical generating functions may be present as side chains 57 or as part of the polymer backbone."58"261 Thus, amphiphilic block copolymers were synthesized using the polymeric initiator 21 formed from the reaction between an a,to-diol and AIBN (Scheme 7.22).26 Some further examples of multifunctional initiators were mentioned in Section 3.3.3.2. It is also possible to produce less well-defined multifunctional initiators containing peroxide functionality from a polymer substrate by autoxidalion or by ozonolysis.-0... 

The triethylsilane reduction of the peroxy ethyl ether shown in Eq. 307 takes place at the C-0 bond of the methyl ether without reduction of either the iodide or the peroxide functionalities (Eq. 307).499In contrast, a bridged peroxy ether undergoes reduction of both C-0 bonds of the peroxide linkage rather than at the ether bridge (Eq. 308) 499... 

Activators of Hydrogen Peroxide, Functional Catalase-Peroxidase Replicas 494... 

Inorganic acids with a peroxide function are given the IUPAC name above, which distinguishes them from the organic peroxyacids. Collectively they are a group of very powerful oxidants, individual compounds being ... 

For more than forty years the Bartlett butterfly TS was the generally accepted mechanism for peracid epoxidation and numerous experimental studies supported this transition structure" " . During these formative years theoretical calculations did not play a major role due to limitations of available methods that could adequately treat the peroxide functional group. Theoretical contributions in 1978 were at the Hartree-Fock (HF) level since... 

A Perkin-Elmer Model 21 infrared spectrophotometer was used to detect and to estimate the hydroxylic and carbonyl functions in the oxidized product mixtures. The organic hydroperoxide and peroxide functional groups in the product mixtures were determined by an iodine liberation and titration procedure (11). In order to get reproducible results, it is necessary to pretreat the olefins with about 10 weight % activated silica or alumina for several hours with agitation to remove adventitious peroxides and impurities. Sodium bisulfite solution rapidly destroys hydroperoxides but does not destroy peroxides completely. The hydroperoxides and peroxides decomposed extensively during attempted distillation at about 1 mm. of Hg partial vacuum. We had some success in concentration by liquid chromatography over silica gel the unconverted olefins are eluted with n-hexanes, and a hydroperoxide-peroxide... 

Results obtained in glass apparatus are summarized in Figure 1. The unsaturation falls off nearly linearly after a short induction period. After the hydroperoxide functional groups attain their maximum, the olefin disappearance decreases and becomes nonlinear as it is consumed by reaction to form polymeric dialkyl peroxide functions. The maximum concentration of polymeric dialkyl peroxide occurs well after the maximum alkenyl hydroperoxide concentration, giving the appearance of a sequential oxidation mechanism. Infrared and gas-liquid chromatographic analyses showed that hydroxylic derivatives, carbonyl derivatives, and lower molecular weight olefins continued to build up as by-products as the oxidation proceeded, as does the acidity titer. 

The experimental autoclave results are summarized in Table I and Figures 2 through 4. Autoclave product compositions are expressed in weight percent, assuming that one peroxide function per olefin unit is incorporated in the polymeric dialkyl peroxides (17, 19). 

The peroxide 0-0 bond is relatively weak therefore, reactions at another site of a molecule, which bears a peroxide function, are carefully controlled. The tolerance of the peroxy 0-0 bond to a number of metal hydrides including 1,2-dioxepane derivatives was studied (Equations 10-12). For example, 58 was examined with the targeted reduction site being an ester group. The peroxide bond survived these reduction conditions <2005JOC4240>. 

In competition with 02-addition [reaction (25)], the (3-alkylperoxide species may undergo radical-induced cleavage of the peroxide function [reaction (26) Bloodworth et al. 1984 Phulkar et al. 1990]. 

Kulik et al. [205] focused their studies on the identification of chemical species formed during the treatment of polyolefins such as polyethylene or polypropylene by gaseous ozone or ozone in aqueous medium. Experimental conditions have a great influence on the nature of the obtained species. For example, peroxidic functions, carboxylic acids, and ketones have been identified, aldehydes being absent of the surface of the materials. It must be noted here the instability of the peroxidic species formed during the treatment... 

Attachment of substituents incompatible to ozone required a different general synthetic route. For example, allyl acid 59 displayed poor chemoselectivity on exposure to ozone. Contrary to reports of alkaline decomposition of the lactone-acetal-peroxide functionality,16 the enolate of the prefabricated tetracycle 42 could be generated at low temperature and alkylated. As a notable example, this methodology produced a single allylated tetracycle, the a-epimer 59. This initial alkylation product was unchanged after prolonged acid treatment, and structure 57 was... 

However, there is a problem with each of these formulations (5) advises that the second oxygen atom is bonded to the first oxygen atom, rather than forming the desired bond to the nitrogen atom. Such a code is indicative of a "peroxide" functional group. Instead of this incorrect constitution, the desired systemic name+ of this molecule is ... 

In a first step, the azo function is decomposed at 60 °C, followed by incorporation of PMMA sequences by decomposition of the peroxidic function at 30 °C. The reverse sequence, that is to say, decomposition of perester function followed by that of the azo one, is also possible. For instance, Sheppard et al. patented the synthesis of 42 original azo peresters and polymeric initiators [18,19], some of them being successfully used for the preparation of block copolymers as evidenced by the following examples ... 

Glazomitskii et. al. [102] have described a difunctional initiator generated by ozonization of the end groups of oligomers of acrylic acid esters. It has peroxidic functional groups. A similar initiator was described by Galubei et. al. [103] the peroxy end groups are connected by a polyoxirane chain... 

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