Hydroquinone from quinones

The equation for the formation of hydroquinone from quinone has been given above- All homologous quinones react in the same way. The hydroquinones are di-acid phenols, which dissqlve in alkalies and show all the properties of phenols. They are not volatile with steam. 

Hydronium ion, electrostatic potential map of, 145 Hydrophilic, 63 Hydrophobic. 63 Hydroquinone, 631 from quinones, 631 Hydroxide ion, electrostatic potential map of. 53. 145... 

Quinone(s), 631 from phenols. 631 hydroquinones from, 631 reduction of, 631... 

Since the substituted hydroquinones and quinone dioximes are better electron donors than hexamethylbenzene (as established by cyclic voltammetric studies), donor-induced disproportionation (to generate NO+ NOf) is even more favored. Furthermore, either two successive one-electron oxidations of hydro-quinone (or quinone dioxime) by NO + followed by the loss of two protons from the dication or two sequential oxidation/deprotonation steps complete the oxidative transformation in equation (97). Importantly, the ready aerial oxidation of NO to NO provides the basis for the nitrogen oxide catalysis of hydroquinone (or quinone dioxime) autoxidation as summarized in Scheme 26. 

The processes of oxidation of cyclohexadiene, 1,2-substituted ethenes, and aliphatic amines are decelerated by quinones, hydroquinones, and quinone imines by a similar mechanism. The values of stoichiometric inhibition coefficients / and the rate constants k for the corresponding reactions involving peroxyl radicals (H02 and >C(0H)00 ) are presented in Table 16.3. The/coefficients in these reactions are relatively high, varying from 8 to 70. Evidently, the irreversible consumption of quinone in these systems is due to the addition of peroxyl radicals to the double bond of quinone and alkyl radicals to the carbonyl group of quinone. 

Anderson B, Oglesby F Corneal changes from quinone-hydroquinone exposure. AMA Arch Ophthalmol 59 495-501, 1958... 

It has now been found that the quinones 13, 14 and 15 from the aerobic oxidation of veratryl alcohol by lignin peroxidase were also reduced by fungal mycelium to yield the corresponding hydroquinones. For quinone 14 this reduction had already been reported by Buswell et al. (17) in a study of vanillic acid metabolism. 

Urban S, Capon RJ (1996) Deoxyspongiaquinones New Sesquiterpene Quinones and Hydroquinones from a Southern Australian Marine Sponge Euryspongia sp. Aust J Chem 49 611... 

B. Anderson, and F. Oglesby, Corneal changes from quinone-hydroquinone exposure. Arch. Ophthalmol. 59 495, 1958. 

When threatened, the bombardier beetle mixes hydroquinone and H202 with enzymes. Peroxide oxidizes hydroquinone to quinone, and the strongly exothermic reaction heats the solution to boiling. The hot, irritating liquid sprays from the tip of the insect s abdomen. 

The commercial route to hydroquinone from aniline (see Chapter 4) proceeds via the isolated intermediate henzo-l,4-quinone (Scheme 11.6). 

Dithioacetic acid derivatives add to 1,4-benzo- or 1,4-naphthoquinones to give, after oxidation of the adduct with silver oxide or chloranil, the quinones 217 and 218 (69LA103). Quinones 218 were prepared also from 2,3-dichloro-1,4-naphthoquinone and salts of dithiocarbamic acids (51JA3459) and those of type 219 by oxidation of the corresponding hydroquinones. From reduction potentials and the semiquinone formation constants, it was concluded that their anion radicals are thermodynamically stable (86CC1489). 

Barium manganate, BaMn04, is commercially available. The dark-blue crystals are obtained from aqueous solutions of barium chloride and potassium permanganate [552, 555]. It oxidizes alcohols, especially benzylic alcohols, to carbonyl compounds [552, 555] hydroquinone to quinone [555] benzylamines to benzaldehydes [555] aromatic amines to azo compounds [555] and phosphines to phosphine oxides [555],... 

Oxidations. Clean products are generally obtained by using alumina-supported reagents. For the oxidative dimerization of thiols by OMSO or NalOj, the conversion of hydroquinones to quinones and 2-naphthols to BINOLs in the presence of CuSO, the formation of lactones from a,co-diols under the influence of NaBrOj, and the hydrolytic defluorination of certain perfluoroalkylarenes, alumina has unique or positive effects. 

In aqueous solution. Use of a solution of chromic acid prepared from dilute sulfuric acid and sodium dichromate dihydrate is illustrated by the oxidation of hydroquinone to quinone, isolated by a tedious process in 86-92% yieid. ... 

Unsaturated ketones68 and sulfinic acids afford y-oxo sulfones and (arylsulfonyl)hydroquinones are formed from quinones and arenesulfinic acids by 1,4-addition. According to work by Hinsberg and others69 occurrence of this reaction is direct evidence of a quinonoid structure if ortho- or para-positions are free and neither hydroxyl nor amino groups are present as substituents in the quinone. 

Electrochemical oxidation of carbon in 1 mol L" H2S04 is claimed to result in hydroquinone- or quinone-like groups in different environments however there is not much support for these findings in later work . The anodically produced surface film differs from that chemically formed . 

Oxidation, This nitroxyl (1) is similar to Fremy s salt [1, 940 (KS03)2N0-] in that it oxidizes phenols and hydroquinones to quinones, usually in satisfactory yields. Secondary alcohols are oxidized to ketones in high yield but the aldehydes formed from primary alcohols are subject to further oxidation. ... 

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