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| | Appearance= | | Appearance= | ||
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| | MeltingPtC=39 | |||
| | BoilingPt= | |||
| | pKa=2.64<ref>Brown, H.C., et al., in Baude, E.A. and Nachod, F.C., ''Determination of Organic Structures by Physical Methods'', Academic Press, New York, 1955.</ref> | |||
| | Solubility= | |||
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| |Section3={{Chembox Hazards | |||
| | MainHazards= | |||
| | FlashPt= | |||
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| '''Cinnoline''' is an ] ] with the formula C<sub>8</sub>H<sub>6</sub>N<sub>2</sub>. It is ]ic with ], ] and ]. | |||
| ==Properties== | |||
| The free base can be obtained as an oil by treatment of the ] with base. It co-crystallizes with one molecule of ether as white silky needles, (m.p. 24-25 °C) upon cooling ethereal solutions. The free ] melts at 39 °C. It has a taste resembling that of ] and leaves a sharp irritation for some time. Cinnoline derivatives are obtained from oxycinnolin carboxylic acid, which is formed by digesting orthophenyl propiolic acid diazo chloride with water. Oxycinnolin carboxylic acid on heating gives oxycinnoline, melting at 225 °C, which with ] gives chlorcinnolin. This substance is reduced by ]s and ] to dihydrocinnolin. | |||
| ==Discovery and synthesis== | |||
| The compound was first obtained in impure form by cyclization of the ] ''o''-C<sub>6</sub>H<sub>4</sub>(NH<sub>2</sub>)C≡CCO<sub>2</sub>H in water to give 4-hydroxycinnoline-3-carboxylic acid. This material could be decarboxylated and the hydroxyl group reductively removed to give the parent heterocycle. This reaction is called the '''Richter cinnoline synthesis'''<ref>] "Über Cinnolinderivate" Chemische Berichte, 1883, volume 16, pp 677-683.</ref> Improved methods exist for its synthesis. It can be prepared by ] of ] with freshly precipitated ]. It can be isolated as the ].<ref>Parrick, J.; Shaw, C. J. G. and Mehta, L. K., "Pyridazines, cinnolines, benzocinnolines and phthalazines", Rodd's Chemistry of Carbon Compounds (2nd Edition), 2000, 4, 1-69.</ref> | |||
| '''Cinnolines''' are cinnoline derivatives. A classic ] for synthesizing cinnolines is the '''Widman-Stoermer synthesis'''<ref>''Name Reactions and Reagents in Organic Synthesis'' Bradford P. Mundy, Michael G. Ellerd, Frank G. Jr. Favaloro '''2005''' ISBN 0471228540</ref>, a ] of an α-vinyl- ] with ] and ]: | '''Cinnolines''' are cinnoline derivatives. A classic ] for synthesizing cinnolines is the '''Widman-Stoermer synthesis'''<ref>''Name Reactions and Reagents in Organic Synthesis'' Bradford P. Mundy, Michael G. Ellerd, Frank G. Jr. Favaloro '''2005''' ISBN 0471228540</ref>, a ] of an α-vinyl- ] with ] and ]: | ||
Revision as of 07:46, 23 September 2011
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| Names | |
|---|---|
| IUPAC name Cinnoline | |
| Other names BenzEMBL = 479792 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
 Y verify (what is ?)
Infobox references
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|Section2={{Chembox Properties | Formula=C8H6N2 | MolarMass=130.15 g/mol | Appearance= | Density=
Cinnolines are cinnoline derivatives. A classic organic reaction for synthesizing cinnolines is the Widman-Stoermer synthesis, a ring-closing reaction of an α-vinyl- aniline with hydrochloric acid and sodium nitrite:
The sodium nitrite is first converted to nitrous acid which then forms the electrophilic intermediate dinitrogen trioxide. The next intermediate is the stable Nitrosamine with goes on to lose water forming the diazonium salt which then reacts with the vinyl group in the ring-closing step. A conceptually related reaction is the Bamberger triazine synthesis towards triazines.
Another cinnoline method is the Borsche cinnoline synthesis.
Safety
Cinnoline is toxic.
See also
References
- Name Reactions and Reagents in Organic Synthesis Bradford P. Mundy, Michael G. Ellerd, Frank G. Jr. Favaloro 2005 ISBN 0471228540