Rearrangements of other N-substituted aromatic amines

A large number of rearrangement reactions of N-substituted aromatic amines are known apart from the five examples already discussed. In LXII 

Diazoamino compounds, (LXIII) produced by coupling a diazonium ion with a primary aromatic amine, viz. 

If the para position is blocked then the amino group will enter the ortho position. Friswell and Green102 suggested an acid-catalysed fission of LXIII to form the diazonium ion and the primary aromatic amine (the reversal of its formation) 

A rearrangement reaction which has been much studied, and in many ways resembles the reaction of phenylhydroxylamines, is the Wallach rearrangement111 of azoxybenzene (LXVI) to give para hydroxyazobenzene (LXVII), viz. 

The reaction is clearly acid-catalysed and analysis115 of the variation of the rate-coefficient with acidity (H0) in the range 75-96 % sulphuric acid has indicated that a second proton transfer is taking place. This is because, at these acidities, spectroscopic measurements show that the azoxybenzene is completely protonated, yet the observed first-order rate coefficient increases along the range from 0.016 x 10 5 to 26.1 x 10 5 sec-1 at 25 °C. For a scheme like 

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