Diazo Coupling Azo Dyes

Being positively charged, aryldiazonium ions are electrophiles. They are weak electrophiles, however, because the positive charge can be delocalized through resonance. 

Write the resonance contributors for the benzenediazonium ion that show how the nitrogen farthest from the benzene ring can become electrophilic. 

In the second contributor, the nitrogen at the right has only six electrons it 

PROBLEM 11.21 Draw resonance contributors that show that the positive charge in benzenediazonium ion can also be delocalized to the ortho and para carbons of the benzene ring. (CAREFUL These contributors have two positive charges and one negative charge.) 

Aryldiazonium ions react with strongly activated aromatic rings (phenols and aromatic amines) to give azo compounds. For example, 

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