Diazohydroxide electrophilic

Metabolic a-hydroxylation of NNN and NPy has been studied. This process may be the activation pathway for NNN and NPy since electrophilic diazohydroxides and carbonium ions are generated upon decomposition of the unstable intermediates a-hydroxyNPy,... 

Fragmentation reactions which give rise to multiple bonding between nitrogen atoms are exemplified by decompositions of aromatic diazohydroxides in acidic media to give aryl cations, nitrogen and water. Such reactions generally occur in two steps and the intermediate diazonium ion is well characterised by its electrophilic properties. 

Couplings between arenediazonium cations and phenols take place most rapidly in slightly alkaline solution. Under these conditions an appreciable amount of the phenol is present as a phenoxide ion, ArO , and phenoxide ions are even more reactive toward electrophilic substitution than are phenols themselves. (Why ) If the solution is too alkaline (pH > 10), however, the arenediazonium salt itself reacts with hydroxide ion to form a relatively unreactive diazohydroxide or diazotate ion ... 

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