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Phenol Oxidation With Hypervalent Iodine Reagents
Phenol oxidation with hypervalent iodine reagents leads to the formation of quinone-type products or iodonium ylides, depending on the structure of the phenol. Trapping of either product is possible with a suitable reagent, and this method is often employed in tandem with a second process. Introduction In the presence of hypervalent iodine(III) reagents such as iodobenzene diacetate (IBD) or iodobenzene di(trifluoroacetate) (IBTA), phenols undergo oxidation to either quinones. or iodonium ylides. Phenols with an electron- withdrawing group in the ''para'' position form the latter, while most other phenols give the former (or derivatives thereof). Direct transformation of quinone products may occur through intramolecular Diels-Alder or Michael-type reactions. Bis(phenol) substrates undergo oxidative coupling under these conditions. Iodonium ylides are relatively stable, versatile compounds that undergo substitution and cycloaddition reactions. They are represented using two resonance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodobenzene Diacetate
(Diacetoxyiodo)benzene, also known as phenyliodine(III) diacetate (PIDA) is a hypervalent iodine chemical with the formula . It is used as an oxidizing agent in organic chemistry. Preparation This reagent was originally prepared by Conrad Willgerodt by reacting iodobenzene with a mixture of acetic acid and peracetic acid: :CHI + CHCOH + CHCOH → CHI(OCCH) + HO PIDA can also be prepared from iodosobenzene and glacial acetic acid: : CHIO + 2 CHCOH → CHI(OCCH) + HO More recent preparations direct from iodine, acetic acid, and benzene have been reported, using either sodium perborate or potassium peroxydisulfate as the oxidizing agent: : CH + I + 2 CHCOH + KSO → CHI(OCCH) + KI + HSO + KHSO The PIDA molecule is termed hypervalent as its iodine atom (t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2,3-dichloro-5,6-dicyano-1,4-benzoquinone
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C6Cl2(CN)2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols, and steroid ketones. DDQ decomposes in water, but is stable in aqueous mineral acid. Preparation Synthesis of DDQ involves cyanation of chloranil. J. Thiele and F. Günther first reported a 6-step preparation in 1906. The substance did not receive interest until its potential as a dehydrogenation agent was discovered. A single-step chlorination from 2,3-dicyanohydroquinone was reported in 1965. Reactions The reagent removes pairs of H atoms from organic molecules. The stoichiometry of its action is illustrated by the conversion of tetralin to naphthalene: :2 C6Cl2(CN)2O2 + C10H12 → 2 C6Cl2(CN)2(OH)2 + C10H8 The resulting hydroquinone is poorly soluble in typical reaction solvents (dioxane, benzene, alkanes), which facilitates workup. Solutions of DDQ in benzene are red, due to the formation of a charge- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinone
The quinones are a class of organic compounds that are formally "derived from aromatic compounds benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds, resulting in "a fully Conjugated system, conjugated cyclic diketone, dione structure". The archetypical member of the class is 1,4-benzoquinone or cyclohexadienedione, often called simply "quinone" (thus the name of the class). Other important examples are 1,2-benzoquinone (''ortho''-quinone), 1,4-naphthoquinone and 9,10-anthraquinone. The name is derived from that of quinic acid (with the suffix "-one" indicating a ketone), since it is one of the compounds obtained upon oxidation of quinic acid. Quinic acid, like quinine is obtained from cinchona bark, called quinaquina in the indigenous languages of Peruvian tribes. Properties Quinones are oxidized derivatives of aromatic compounds and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
