Peroxy formation

Step 1 The peroxy acid adds to the carbonyl group of the ketone This step is a nucleophilic addition analogous to gem diol and hemiacetal formation... 

Oxidation begins with the breakdown of hydroperoxides and the formation of free radicals. These reactive peroxy radicals initiate a chain reaction that propagates the breakdown of hydroperoxides into aldehydes (qv), ketones (qv), alcohols, and hydrocarbons (qv). These breakdown products make an oxidized product organoleptically unacceptable. Antioxidants work by donating a hydrogen atom to the reactive peroxide radical, ending the chain reaction (17). 

Conversion of Aromatic Rings to Nonaromatic Cyclic Structures. On treatment with oxidants such as chlorine, hypochlorite anion, chlorine dioxide, oxygen, hydrogen peroxide, and peroxy acids, the aromatic nuclei in lignin typically ate converted to o- and -quinoid stmctures and oxinane derivatives of quinols. Because of thein relatively high reactivity, these stmctures often appear as transient intermediates rather than as end products. Further reactions of the intermediates lead to the formation of catechol, hydroquinone, and mono- and dicarboxyhc acids. 

Oxidation. AH polyamides are susceptible to oxidation. This involves the initial formation of a free radical on the carbon alpha to the NH group, which reacts to form a peroxy radical with subsequent chain reactions leading to chain scission and yellowing. As soon as molten nylon is exposed to air it starts to discolor and continues to oxidize until it is cooled to below 60°C. It is important, therefore, to minimize the exposure of hot nylon to air to avoid discoloration or loss of molecular weight. Similarly, nylon parts exposed to high temperature in air lose their properties with time as a result of oxidation. This process can be minimized by using material containing stabilizer additives. 

As the quinone stabilizer is consumed, the peroxy radicals initiate the addition chain propagation reactions through the formation of styryl radicals. In dilute solutions, the reaction between styrene and fumarate ester foUows an alternating sequence. However, in concentrated resin solutions, the alternating addition reaction is impeded at the onset of the physical gel. The Hquid resin forms an intractable gel when only 2% of the fumarate unsaturation is cross-linked with styrene. The gel is initiated through small micelles (12) that form the nuclei for the expansion of the cross-linked network. 

Oxygen donors like peroxy acids, ozone, and pyridine IV-oxides cause carbon-carbon cleavage, perhaps by formation of a perepoxide (43 Scheme 30) (81JCS(P1)1871). Other oxidants have also been reported to react with oxiranes (64HC( 19-1)228). 

Destruction of the aromatic ring is the mam reaction in the oxidation of tetrafluoro-o phenyleiiediamine with lead tetraacetate by products are tetrafluorobenzotnazole and tetrafluorochinoxalme denvatives [92] (equation 85) Polyfluonnated benzylideneanilines are oxidized by peroxyacids to different products dependmg on reaction contitions at room temperature the benzylidene carbon is oxidized with the formation of peroxy bonds [93 94] (equation 86), whereas in refluxing agent, the azomethme bond is cleaved [93] (equation 86) Pentafluorobenzylidencanilme is oxidized by peroxyacetic acid in dichlo-romethane at room temperature to perfluorobenzoic acid in a 77% yield [93]... 

The reactions of the diazine radicals with O2 were studied at the B3-LYP/6-311-1- G level (Scheme 59) [00JPC(A)6088]. Formation of dioxiranyl radical intermediates was found to be the most important pathway from the peroxy precursor. DFT-derived geometric parameters of pyrimidiniumolate are in good agreement with experimental data obtained for 1,2,3,5-tetraphenylpyrimidiniumolate [97MI1]. 

Ameisen-. formic, -aldehyd, n. formaldehyde. -amylMther, -amylester, m. amyl formate, -ather, m. formic ether (ethyl formate), geist, m. (Pharm.) spirit of ants (a mixture of formic acid, alcohol and water), -naphta, n. = Ameisenather. -persaure, /. peroxy-formic acid, performic acid, ameisensauer, a. of or combined with formic acid, formate of. — ameisensaures Salz, formate. 

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)... 

Peroxide precipitation at Rocky Flats 376 Peroxy complex, Pu(IV), formation. . 267... 

The above-mentioned mode of reactions changes when the irradiation is carried out in the presence of gases such as oxygen. In this case, energy transfer, the reaction of oxygen with polymer radicals [32] (leading to the formation of peroxy radicals) and other reactions may affect the type and concentration of products formed [33]. The same can be said for certain additives mixed into the elastomer for one or the other purpose. 

---