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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Look at other dictionaries:

  • 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 — noun Etymology: International Scientific Vocabulary quinine + one Date: 1853 1. either of two isomeric cyclic crystalline compounds C6H4O2 that are derivatives of benzene 2. any of various usually yellow, orange, or red quinonoid compounds… …   New Collegiate Dictionary

  • quinone — Aromatic dicarbonyl compound derived from a dihydroxy aromatic compound. Ubiquinone (coenzyme Q) is a dimethoxy dicarbonyl derivative of benzene involved in electron transport. Other quinones may act as tanning agents …   Dictionary of molecular biology

  • quinone — noun any of a class of aromatic compounds having two carbonyl functional groups in the same six membered ring …   Wiktionary


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