Diazohydroxides, Diazoethers and Related Species
Hydroxylamines, Oximes and Hydroxamic Acids (2010)
Published Online: 15 OCT 2010
Copyright © 2009 John Wiley & Sons, Ltd. All rights reserved.
Patai's Chemistry of Functional Groups
How to Cite
D. Bravo-Díaz, C. 2010. Diazohydroxides, Diazoethers and Related Species. Patai's Chemistry of Functional Groups. .
- Published Online: 15 OCT 2010
Arenediazonium, ArN2+, ions may function as Lewis acids reacting with nucleophiles (Lewis bases, Nu− or NuH followed by loss of a proton) to give covalently bonded adducts, ArN2-Nu, at the β-nitrogen of the arenediazonium ion, which is the electrophilic reactive center. Typical examples of covalently bonded adducts are the azo dyes (C-coupling) but atoms other than C may be involved and the present chapter will mainly focus on the chemistry of O-coupling adducts of the type ArN=N-Nu, e.g., where Nu = OH− (formation and decomposition of diazohydroxides and diazoates), Nu = RO−, ArO−, ROH and cyclodextrins (formation and decomposition of diazoethers), with special emphasis on the kinetics and mechanism of the reactions involved. We will also cover, to a lower extent, those reactions with other nucleophiles leading to S-, N- and P-adducts. O-coupling reactions are complicated by two major features. First, the formed adducts may display geometrical isomerism, leading to the E-(syn) and Z-(anti) forms, which show different stability and can be interconverted to each other by acid catalyzed processes. Second, some of the O-adducts formed may be, in turn, components of a Lewis acid-base equilibrium, for example between ArN2+ and OH− ions, and hence may undergo further reactions.
- diazo compounds;
- heterolytic mechanism;
- homolytic mechanism;
- aryl radicals