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Concept
Organic peroxides
Résumé
In organic chemistry, organic peroxides are organic compounds containing the peroxide functional group (). If the R′ is hydrogen, the compounds are called hydroperoxides, which are discussed in that article. The O−O bond of peroxides easily breaks, producing free radicals of the form (the dot represents an unpaired electron). Thus, organic peroxides are useful as initiators for some types of polymerization, such as the acrylic, unsaturated polyester, and vinyl ester resins used in glass-reinforced plastics. MEKP and benzoyl peroxide are commonly used for this purpose. However, the same property also means that organic peroxides can explosively combust. Organic peroxides, like their inorganic counterparts, are often powerful bleaching agents.
Tert-Butyl hydroperoxide Structural Formula V2.svg|[[Tert-Butyl hydroperoxide|''tert''-Butyl hydroperoxide]], a [[hydroperoxide]] (formula: ROOH) that is used to epoxide alkenes.
Dicumyl peroxide.svg|[[Dicumyl peroxide]], a dialkyl peroxide (formula: ROOR) that is used to initiate polymerizations.
Tert-Butylperoxybenzoat Strukturformel.svg|[[tert-Butyl peroxybenzoate|''tert''-butylperoxybenzoate]], a peroxy ester (formula: {{chem2|1=RCO3R'}}) that used as a radical initiator.
Benzoyl-peroxide.svg|[[dibenzoyl peroxide]], a diacyl peroxide (formula: {{chem2|1=(RCO2)2)}}) is also used as an initiator for polymerizations.
Ethaneperoxoic acid 200.svg|[[Peroxyacetic acid]], a [[peroxycarboxylic acid]] (formula: {{chem2|1=(RCO3H}}), is a reagent in [[organic synthesis]].
Organic peroxides are classified (i) by the presence or absence of a hydroxyl (-OH) terminus and (ii) by the presence of alkyl vs acyl substituents. One gap in the classes of organic peroxides is diphenyl peroxide. Quantum chemical calculations predict that it undergoes a nearly barrierless reaction akin to the benzidine rearrangement.
The O−O bond length in peroxides is about 1.45 Å, and the R−O−O angles (R = H, C) are about 110° (water-like). Characteristically, the C−O−O−R (R = H, C) dihedral angles are about 120°.
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