Peroxides cleavage

Substitution reactions on dialkyl peroxides without concurrent peroxide cleavage have been reported, eg, the nitration of dicumyl peroxide (44), and the chlorination of di-/ fZ-butyl peroxide (77). Bromination by nucleophilic displacement on a-chloro- or a-hydroxyalkyl peroxides with hydrogen bromide produces a-bromoalkyl peroxides (78). 

Fig. 4. Heterolytic and hemol3itic pathways of peroxide cleavage by myoglobin, (modified from Ref. 198).

Substitution reactions on dialkyl peroxides without concurrent peroxide cleavage are known e.g the nitration of dicumyl peroxide and the chlorination of di-lcrt-butyl peroxide. 

John DCA, Douglas KT (1996) A common chemical mechanism used for DNA cleavage by copper(ll) activated by thiols and ascorbate is distinct from that for copper (II) hydrogen peroxide cleavage. Transition Met Chem 21 460-463... 

Cleavage of cyclopropanes. In the absence of a solvent, cyclopropanes are reductively cleaved by diborane. Thus norcarane heated with diborane at 100 for 1-2 hrs. gives the alkylborane (2), identified by peroxide cleavage to cyclohexyl-methanol (3). No reaction occurred in tetrahydrofurane. 

Peroxide cleavage of a-diketones. Leffler found that perchloric acid is an effective catalyst for the cleavage of a-diketones with hydrogen peroxide. For example, a mixture of 1.02 g. of benzil, 25 ml. of acetic acid, 1 ml. of 95% hydrogen... 

An even more complex mechanistic jungle appears in the peroxide cleavage of boronic acids 173, 174). Kuivila and his co-workers have again... 

Boyer, P. D. (ed.) The Enzymes, Vol. 13, Dehydrogenases, Oxidases, Hydrogen Peroxide Cleavage. Academic Press, New York 1977... 

The oxidation of an aldose to the next lower aldose with ammonium vanadate in sulphuric acid or perchloric acid has been mentioned in Chapter 2. Isbell and his co-workers have extended their studies of peroxide-cleavage reactions to include such carbocyclic compounds as 2,3,4,6/5-pentahydroxycyclohexanone (426) and x> /o-trihydroxycyclohexane-l,2,3-trione, which gave DL-glucaric acid (see Scheme 145) and xylaric acid, respectively, on oxidation. Mechanisms... 

Fig. 11.11. Enzymatic formation mechanism of aldehydes and Ce alcohols, responsible for grassy flavors (Crouzet, 1986). (1) [Acyl]hydrolase (2) lipoxygenase in the presence of oxygen (3) peroxide cleavage enz3me (4) alcohol dehydrogenase...

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