Hydrogen peroxy adds

Oxidations of aromatic aldehydes to formyl esters of phenols and to phenols are accomplished by hydrogen peroxide [171, 172, 173] or by organic peroxy adds such as peroxyacetic acid [259], peroxybenzoic acid [302], and m-chloroperoxybenzoic acid [5/5, 318] (equations 360-363). 

Peroxides, test for, 41, 92 Peroxy adds from carboxylic acids and 70% hydrogen peroxide, 43, 96 Peroxybenzoic Acro, 43,93 iodometric analysis of, 43, 94 Peroxystearic add, 43,96 Phenacylamine hydrochloride, 41, 82... 

The vise of per- is preferably restricted to acids derived from the highest oxidation stages of some elements e.g., HCIO4, perchloric acid) to distinguish them from acids derived from hydrogen peroxide and better called peroxy adds e.g., H2SO6, peroxy mono)sulfuric add). 

Free radical (3) can rearrange, add oxygen to form a peroxy free radical, abstract a hydrogen from a methylene group between double bonds, combine with another free radical, or add to a conjugated double-bond system. 

Hydrogenation, of gallic add with rhodium-alumina catalyst, 43, 62 of resorcinol to dihydroresorcinol, 41,56 Hydrogen peroxide, and formic acid, with indene, 41, 53 in oxidation of benzoic add to peroxy-benzoic add, 43, 93 in oxidation of ieri-butyl alcohol to a,a/r, a -tetramcthyltetra-methylene glycol, 40, 90 in oxidation of teri-butylamine to a,<, a, a -tetramethyltetra-methylenediamine, 40, 92 in oxidation of Crystal Violet, 41, 2, 3—4... 

The rate of transfer is accelerated by electron-releasing substituents on the aromatic ring of the antioxidant and retarded by steric protection of the labile hydrogen or its replacement by deuterium. The subsequent fate of the radical A determines the over-all kinetics of the inhibited reaction and the practical usefulness of the antioxidant. If A is a fairly stable phenoxy radical, it will probably add a peroxy radical or dimerize. 

The abstraction of a hydrogen atom occurs preferentially at the tertiary carbon of the structure, leading to a polystyryl radical. This radical adds to oxygen to form a peroxy radical. By abstraction of another hydrogen atom, the peroxy radical leads to a hydroperoxide. Hydroperoxides have an IR absorption at 3450 cm-1. The decomposition of the hydroperoxide either by photolysis or by thermolysis gives an alkoxy radical that may react in several ways ... 

Infifaied meaauitments indicate that peroxy acids aiv present in solution largely in the monomeric, jntramolecularly hydrogen-bonded form (XXXVIII), in accordance with the fact tli.-ki-they. are more volatile than the oortesponding carboxylic adds. 

Polymer alkyl radicals (P-) add molecular oxygen to produce polymer peroxy radicals (P00-) which may further abstract hydrogen from the same and/or neighbouring polymer molecule. In this way a cycle of free ra c J oxidations occurs and is known as "auto-xodiation" process ... 

The decomposition may occur either uni- or bimolecularly to form alkoxy and peroxy radicals. These oxy radicals abstract a labile hydrogen from the hydrocarbon to produce either an alcohol or a hydroperoxide. The alkyl radical thus formed readily adds oxygen to reform a peroxy radical, and the process continues. When the autoxidation occurs In the absence of an antioxidant, the termination of the kinetic chain occurs chiefly by the combination of two peroxy radicals. This termination Is a source of alkoxy radicals which can undergo chain scission and give rise to volatile products and carbonyl groups. 

The peroxy radical of structure (XVIIa) can add to a neighboring double bond forming (XXIII). Further polycyclic peroxidation can occur and hydrogenation (XXV), epoxldatlon (XXVIII), or addition of the peroxy radical to a non-nelghborlng double bond terminates cycllzatlon along the chain. Decomposition of a mono-cycllcperoxy hydroperoxide structure results In an unsaturated and a saturated aldehyde as shown In Figure 1, whereas poly-cycllcperoxy hydroperoxide structures (XXV) and (XXVI) yield only... 

Hydrogen abstraction probably occurs more readily at methylene group 11 (paths 3 and 4) than at 1 (paths 1 and 2) because the chlorine affords stabilization of the allyllc radical formed. Since path 3 can be excluded as noted previously, path 4a appears to be the major choice for cycllzatlon. Path 4a produces only acid chlorides and these absorb strongly in the Ir (29). This is inconsistent with the observation of a comparable absorbtlon of saturated aldehyde (Figure 6). Observation of saturated aldehyde might be an Indication that the Initial peroxy radical in path 4 abstracts hydrogen more readily than It adds to form the cyclic peroxide. Decomposition of the hydroperoxide and B-sclsslon of the corresponding alkoxy radical could account for the formation of both the add chloride and saturated aldehyde observed In the FTIR spectra ... 

Saturation and Oxidation of Double Bonds It is known that radicals can directly add on double bonds [32], which leads in turn to saturation of the double bonds and formation of a new radical. After fixation of oxygen, a peroxy radical is formed followed an hydroperoxide by the classical hydrogen abstraction. Thermal and photochemical decomposition of the hydroperoxides gives alkoxy radicals (Scheme 15.4). 

In basic media, peroxides are deprotonated and the product is a peroxy anion, which reacts with conjugated carbonyl derivatives at the C-terminus (1,4-addition, conjugate addition). Hydrogen peroxide, for example, reacts with base to give the hydroperoxide anion (HOO ), which adds to a, 3-unsaturated ketones, aldehydes... 

A class of peroxides which has received little attention in styrene polymerization is hydroperoxides. In inert solvents, hydroperoxides are relatively stable. However, in a FR environment, they undergo an induced decomposition. The induced decomposition results from the relatively high chain transfer constant (Cj) of the hydroperoxide hydrogen (C, 0.05). Abstraction of the hydrogen by a growing polystyryl radical produces a peroxy radical which adds to styrene. As mentioned peviously, the styrene adduct likely decomposes to form styrene oxide and a tert-alkoxy radical which subsequently initiates polymerization. 

A similar approach was used for the optical detection of phenolic compounds and hydrogen peroxide, using CdTe QDs-enzyme hybrids. For this, mercaptosucdnic add-capped CdTe QDs were first synthesized, after which the horseradish peroxi-dasephenolic compounds by H2O2 to quinone products resulted in an efficient quenching of QD luminescence [197]. 

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