Diazo
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2008-07-09T06:15:32Z
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{{for|a discussion of copiers using the diazo process|Whiteprint}}
[[Image:DiazoResonance.svg|300px|right|Diazo]]'''Diazo''' refers to a type of [[organic compound]] that has two linked nitrogen (azo) compounds. The general formula is R<sub>2</sub>C=N<sub>2</sub>. The simplest example of a diazo compound is [[diazomethane]]. The electronic structure of diazo compounds involves a positive charge on the central nitrogen and negative charge distributed between the terminal nitrogen and the carbon. Some of the most stable diazo compounds are α-diazoketones and α-diazoesters since the negative charge is delocalized into the carbonyl. In contrast, most alkyldiazo compounds are explosive.
Diazo compounds are used as precursors to [[carbene]]s, which are generated by thermolysis or photolysis, for example in the [[Wolff rearrangement]]. They are also used in [[transition metal]]-[[catalyst|catalyzed]] [[cyclopropane|cyclopropanation]] reactions for example in a synthesis of [[tranylcypromine]] <ref>''Catalytic Cyclopropanation of Alkenes Using Diazo Compounds Generated in Situ. A Novel Route to 2-Arylcyclopropylamines'' Varinder K. Aggarwal, Javier de Vicente, and Roger V. Bonnert Org. Lett.; '''2001'''; 3(17) pp 2785 - 2788; (Letter) [http://dx.doi.org/10.1021/ol0164177 Abstract]</ref> <ref>Notes: [[benzaldehyde]] reacts with [[p-toluenesulfonyl hydrazide]] to the [[hydrazone]].Its sodium salt reacts with [[N-Vinylphthalimide]] and [[rhodium acetate]], a [[phase transfer catalyst]] and [[phenylthiocarbamide|PTC]] to the cyclopropane. The phthalimide group is removed by [[hydrazine]]. The product is the [[cis isomer]] but by switching to [[ClFeTPP]] the amount of trans isomer increases to 33%</ref> in ''scheme 1'' {{Ref|scheme1}} in which the sodium salt of benzaldehyde [[tosyl hydrazone]] is converted to a [[rhodium]] [[metal carbene]] through the diazo intermediate.
[[Image:Diazo cyclopropanation.png|600px|center|Scheme 1. Diazo cyclopropanation]]
An unusual [[biomolecule]] sporting a diazo group was synthesized in 2006 with in its final stage the reaction of a [[carbonyl]] group with the [[hydrazine]] ''1,2-bis(tert-butyldimethylsilyl)hydrazine'' to the [[hydrazone]] followed by reaction with the [[periodinane]] ''difluoroiodobenzene'' to the diazo compound <ref>''Total Synthesis of the Diazobenzofluorene Antibiotic (-)-Kinamycin C1'' Xiaoguang Lei and John A. Porco, Jr. [[J. Am. Chem. Soc.]]; '''2006'''; ASAP Web Release Date: 26-Oct-2006; (Communication) {{DOI| 10.1021/ja066621v}}</ref> <ref>''Elusive Natural Product Is Synthesized'' Stu Borman [[Chemical & Engineering News]] October 31, 2006 [http://pubs.acs.org/cen/news/84/i45/8445notw4.html Link].</ref>
[[Image:KinamycinCSynthesis.png|400px|center|Kinamycin C Synthesis]]
Another commercially relevant diazocompound is '''Ethyl diazoacetate''' N<sub>2</sub>CHCOOEt.
A group of isomeric compounds with similar properties are the [[diazirine]]s, where the carbon and two nitrogens are linked as a ring.
== See also ==
* [[Azo compound]]
* [[Diazoalkane 1,3-dipolar cycloaddition]]
* [[Diazonium compound]]
* [[Reprography]]
* [[Whiteprint]]
==References==
<div class="references-small"><references/></div>
[[Category:Functional groups]]
[[es:Diazocompuesto]]
[[fr:Diazo]]
[[ja:ジアゾ化合物]]
[[zh:重氮化合物]]