Phenol when reacts with phthalic anhydrid in presence of gives a compound which is used as the indicator in acid base titratic
The product is :
Methyl Orange
Phenolphthalein
Erichrome-black T
Alizarin Yellow
As we learned
Effects of substituents on acidity of phenols -
1. Electron withdrawing group like
2. Electron donating group like
- wherein
1. Increase the acidic strength of phenol.
2. Decrease the acidic strength of phenol.
Phenolphthalein is the correct answer