Diazo refers to a type of organic compound that has two linked nitrogen (azo) compounds. The general formula is R₂C=N₂. 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 carbenes, which are generated by thermolysis or photolysis, for example in the Wolff rearrangement. They are also used in transition metal-catalyzed cyclopropanation reactions for example in a synthesis of tranylcypromine in scheme 1 in which the sodium salt of benzaldehyde tosyl hydrazone is converted to a rhodium metal carbene through the diazo intermediate.

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

Another commercially relevant diazocompound is Ethyl diazoacetate N₂CHCOOEt.

A group of isomeric compounds with similar properties are the diazirines, 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