The Diazoamino Rearrangement

Diazoamino Rearrangement. When a primary or secondary aromatic amine is used in the coupling process, attack of the diazonium ion usually occurs at the amino group rather than at the nucleus  

of course, is the position of highest electron density. The reaction proceeds to completion by the loss of a proton from the diazoammonium ion (IX). The overall process is a competing reaction with direct coupling, and occasionally it is found to proceed at a slower rate than coupling when the aromatic nucleus of the amino compound or the diazonium ion is particularly reactive.12 

In acid solution, diazoamino compounds give the product that would have been expected from a direct coupling with the aromatic nucleus  

The reaction undoubtedly involves cleavage of the diazoamino compound followed by a recombination step, since p,p -dimethyl diazoaminoben-zene (X) gives p-amino-p -methylazobenzene (XI)13 when it is heated with excess aniline hydrochloride  

Wolff-Kishner Reduction. When the hydrazone of a carbonyl compound is heated with strong alkali, nitrogen is evolved, and two hydrogen atoms are introduced into the molecule  

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It was called the diazoamino rearrangement until 1979, when IUPAC proposed replacing the term diazoamino by triazene. 

The most significant difference from C-coupling is the facile reversibility of N-coupling. In acidic solutions the diazonium ion and the (protonated) amine are regenerated. This back reaction is important in the context of the diazoamino rearrangement discussed later in this Section. 

Evidence that the diazoamino rearrangement can be partly intramolecular was brought forward qualitatively by O ta et al. l,3-Bis(4-methylphenyl)triazene 144 rearranges in acidic ethanol, affording 2-amino-S,4 -dimethylazobenzene 145. In the presence of N,N-dimethylaniIine as a scavenger of diazonium ion, 4-dimethyl-... 

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