Arynes by Loss of Nitrogen from Acyclic Substituents

Arynes by Loss of Nitrogen from Acyclic Substituents 

The energy requirements for generating an unstable intermediate such as an aryne can be substantially decreased if a very stable product such as 

The remaining two reactions, which will be described in this section, are related through the well-known formation of azo compounds 39 by the addition of nucleophiles to diazonium salts (40). The former compounds lose nitrogen by homolytic and the latter by heterolytic processes to give, respectively, aryl radicals and sometimes, as has been recently demonstrated, aryl cations. Because the equilibrium between 39 and 40 is so dependent on solvent, gegenion, and additives, both reactions [equations (8) and (9)] often occur simultaneously.  

The hazard of 41a also can be avoided by reacting it with secondary amines to give the nonexplosive, easily stored triazenes 41e which thermolize 

Another zwitterion intermediate (43), formed by preliminary loss of CO2 from the diazonium carboxylate 41a, also has been suggested, albeit tentatively, several times. Generally this possibility has been ignored and in at least one case the evidence on which the claim was based was explained in another manner.  

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C. Arynes by Loss of Nitrogen from Acyclic Substituents... 

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