Introduction to Dediazoniation in General

The term dediazoniation was introduced by Bunnett as early as 1954. It is now included in the IUPAC system of naming transformations in organic chemistry (IUPAC, 1989 a). 

Dediazoniation refers to all those reactions of diazo and diazonium compounds in which an N2 molecule is one of the products. The designation of the entering group precedes the term dediazoniation, e. g., azido-de-diazoniation for the substitution of the diazonio group by an azido group, or aryl-de-diazoniation for a Gomberg-Bachmann reaction. The IUPAC system says nothing about the mechanism of a reaction (see Sec. 1.2). For example, the first of the two dediazoniations mentioned is a heterolytic substitution, whereas the second is a homolytic substitution. 

There are five groups of reagents that undergo such reactions, namely  

Open-chain and cyclic compounds containing azo groups (-N2 —), such as azoalkanes, azoarenes, pyrazolines, triazolines, etc. may also eliminate N2, but these reactions are called azo-extrusions (IUPAC, 1989 a). The terms denitrogenation and nitrogen extrusion, both used by Adam et al. (1992, 1993) and by Adam and Sengelbach (1993) should not be used. They are superfluous and ambiguous. 

In this chapter we will discuss only the dediazoniation of arenediazonium ions (Group a). The dediazoniation of alkene- and alkanediazonium ions and of diazoalkanes (Groups b, c, and d) will be treated in the second book on diazo chemistry (Zollinger, 1995, Chs. 7-9). 

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