quinone

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, chinone.
[1850-55; QUIN(IC ACID) + -ONE]

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Any member of a class of cyclic organic compounds comprising a six-membered unsaturated ring (see saturation) to which two oxygen atoms are bonded as carbonyl groups (―C=O; see functional group).

This structure plays an important role in theories of chemical structure and colour, since quinones occur as pigments in bacteria, fungi, and certain higher plants; animals containing quinones obtain them from plants they eat. The K vitamins (see vitamin K) are naphthoquinones. The term quinone often specifically denotes para-benzoquinone (C6H4O2), a bright yellow solid with a sharp odour used in manufacturing dyes and fungicides and in photography.

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      any member of a class of cyclic organic compounds containing two carbonyl groups, > C = O, either adjacent or separated by a vinylene group, −CH = CH−, in a six-membered unsaturated ring. In a few quinones, the carbonyl groups are located in different rings. The term quinone also denotes the specific compound para- (p-)benzoquinone (C6H4O2). The quinone structure

plays an important role in theories concerning the relationship of chemical constitution to colour. Quinones occur as biological pigments (biochromes), for example, including the benzoquinones, naphthoquinones, anthraquinones, and polycyclic quinones. The quinones are found in bacteria, in certain fungi, and in various higher plant forms, but in only a few animals. Those animals in which they do occur—e.g., sea urchins, aphids, lac insects, and certain scale insects—obtain their quinone compounds from the plants they eat. The K vitamins are naphthoquinones, as are some chemical indicators of acidity or alkalinity and various dyes used to colour certain types of fabrics.

      Quinones usually are prepared by oxidation of aromatic amines, polyhydric phenols, and polynuclear hydrocarbons. The most important characteristic reaction of quinones is reduction to the corresponding dihydroxy form. In acidic solution, p- benzoquinone is reduced reversibly to hydroquinone (C6H6O2); the reaction is marked by a measurable electrical potential of a magnitude that depends upon the hydrogen ion concentration of the reaction medium and the benzoquinone and hydroquinone concentrations. The so-called quinhydrone electrode, containing equivalent amounts of p-benzoquinone and hydroquinone, is used to determine hydrogen ion concentrations of unknown solutions. Hydroquinone is used principally as a photographic developing agent.

      A bright yellow solid with a sharp odour, p-benzoquinone is slightly soluble in water and melts at about 115° C. Hydroquinone is a white, crystalline solid, soluble in water and alcohol. See also anthraquinone. (anthraquinone)

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Universalium. 2010.

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 — 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.… …   Wikipedia

  • 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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