Quinone

Quinone

:"DDQ" redirects here. DDQ is also the former callsign of a TV station in Toowoomba, Queensland, Australia."

Benzoquinone, or quinone is one of the two isomers of cyclohexadienedione. These compounds have the molecular formula C6H4O2. Orthobenzoquinone is the 1,2-dione, whereas parabenzoquinone is the 1,4-dione.

Orthobenzoquinone is the oxidized form of catechol (1,2-dihydroxybenzene), while parabenzoquinone is the oxidized form of hydroquinone. An acidic potassium iodide solution reduces a solution of benzoquinone to hydroquinone, which is oxidized back with a solution of silver nitrate.

Quinone is also the name for the class of compounds containing either benzoquinone isomers as part of their structure. Quinones are not aromatic, but are diketones.

Biochemistry

Quinone is a common constituent of biologically relevant molecules (e.g. Vitamin K1 is phylloquinone). Others serve as electron acceptors in electron transport chains such as those in Photosystems I & II of photosynthesis, and aerobic respiration. A natural example of the oxidization of hydroquinone to quinone is the spray of bombardier beetles. Hydroquinone is reacted with hydrogen peroxide to produce a fiery blast of steam, a strong deterrent in the animal world. Quinones can be partially reduced to quinols.

Oxidizing agents

Benzoquinone is used in organic chemistry as an oxidizing agent. Stronger quinone oxidising agents exist; for instance: 2,3,5,6-tetrachloro-parabenzoquinone (also known as p-chloranil) and 2,3-dicyano-5,6-dichloro-parabenzoquinone (also known as DDQ). [JerryMarch]

References


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  • quinone — [ kinɔn ] n. f. • 1875; comp. sav. de quina, a. forme abrégée de quinquina ♦ Chim. Composé aromatique dans lequel deux atomes d hydrogène sont remplacés par deux atomes d oxygène. La quinone est un dérivé du benzène ou d hydrocarbures à noyaux… …   Encyclopédie Universelle

  • Quinone — Qui none, n. [Quinine + ketone.] (Chem.) A crystalline substance, {C6H4O2} (called also {benzoketone}), first obtained by the oxidation of quinic acid and regarded as a double ketone; also, by extension, any one of the series of which quinone… …   The Collaborative International Dictionary of English

  • quinone — [kwi nōn′, kwin′ōn΄] n. [ QUIN(IC ACID) + ONE] 1. either of two isomeric compounds, C6H4O2, especially the yellow, crystalline isomer used in making dyes 2. any of a series of compounds of this type …   English World dictionary

  • quinone — /kwi nohn , kwin ohn/, n. Chem. 1. a yellow, crystalline, cyclic unsaturated diketone, C6H4O2, formed by oxidizing aniline or hydroquinone: used chiefly in photography and in tanning leather. 2. any of a class of compounds of this type. Also,… …   Universalium

  • Quinone — Les quinones constituent une série de diènes plutôt que des composés aromatiques comportant un noyau de benzène sur lequel deux atomes d hydrogène sont remplacés par deux oxygènes formant deux liaisons carbonyles (dicétones éthylèniques… …   Wikipédia en Français

  • quinone — (ki non), s. m. ou QUINONE (ki non )), s. f. Terme de chimie. Radical composé qui est le produit de la distillation de l acide quinique …   Dictionnaire de la Langue Française d'Émile Littré

  • quinone — 1,4 benzchinonas statusas T sritis chemija formulė C₆H₄(=O)₂ atitikmenys: angl. p benzoquinone; quinone; 1,4 benzoquinone rus. n бензохинон; хинон; 1,4 бензохинон ryšiai: sinonimas – p benzchinonas sinonimas – 2,5 cikloheksadien 1,4 dionas… …   Chemijos terminų aiškinamasis žodynas

  • Quinone Outside Inhibitors — Les QoI, ou Quinone outside inhibitors sont un groupe de produits chimiques utilisés en agriculture. Les QoI sont des fongicides qui agissent comme inhibiteurs du site d oxydation du coenzyme Q situé sur la face externe du cytochrome b. Les QoI… …   Wikipédia en Français

  • Quinone-interacting membrane-bound oxidoreductase — is a membrane bound protein complex present in the electron transport chain of sulfate reducers (e.g. Desulfovibrio species) and some sulfur oxidizers (such as 0.014) …   Wikipedia

  • quinone diimine — ˈdīəˌmēn noun Etymology: diimine from di + imine 1. : a colorless crystalline compound HN . C6H4 . NH regarded as derived from quinone (sense 1a) by replacement of both oxygen atoms by imino groups but made by oxidation of para phenylenediamine… …   Useful english dictionary

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