Question

Dye Coupling, Complete electropholic aromatic substitution mechanisms (SHOW ALL RESONANCE FOR THE INTERMEDIATES FORMED):

1. 4-diazo N, N-diethylaniline fluoroborate and resorcinol.

2. 4-diazo N, N-diethylaniline fluoroborate and phloroglucinol.

3. 4-diazo N, N-diethylaniline fluoroborate and 2,4-pentanedione.

4. 4-diazo N, N-diethylaniline fluoroborate and 3-methyl-1-phenyl-2-pyrazolin-5-one.

Thanks

Answer 1

Drawn below are the detailed mechanisms for the formation of the dyes

1. Here the lone pair of oxygen assists in the attack of resorcinol on to the diazo linkage to generate the dye product.

2. Again the lone pair of oxygen assists in the formation of C-N linkage of the dye.

3. Tautomer enol of 2,4-pentanedione reacts with the diazo compound to give the product dye.

4. Tautomer of 3-methyl-1-phenyl-2-pyrazolin-5-one reacts with the diazo compound to form the substituted dye product.