(4) based on your answers to q3, explain why 2-naphthol reacts with the diazonium salt at only one position.

Coupling reaction is type of electrophilic substitution reaction. In this reaction diazonium cation reacts with positive charge present on nitrogen. This nitrogen acts as electrophile whereas 2-napthol act as nuceleophile.

The OH group of 2-napthol increases the density at ortho and para position by resonance but para position of 2-napthol is sterically hindered and thus the diazonium cation attacks only at ortho position of 2-napthol.

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