When phenol reacts with phthalic anhydride in presence of \(\mathrm{H}_2 \mathrm{SO}_4\) and heated and hot…
When phenol reacts with phthalic anhydride in presence of \(\mathrm{H}_2 \mathrm{SO}_4\) and heated and hot reaction mixture is poured in \(\mathrm{NaOH}\) solution, then product formed is
alizarin
methyl orange
fluorescein
phenolphthalein.
Solution
Phenol couples with phthalic anhydride in presence of conc. $\mathrm{H}_2 \mathrm{SO}_4$ to form phenolphthalein which is used as an indicator :
