JEE Main20238 Apr 2023Evening ShiftChemistryAlcohols Phenols and EthersActual
A compound ' X ' when treated with phthalic anhydride in presence of concentrated H 2 SO 4 yields ' Y ' . ' Y ' is used as an acid/base indicator. ' X ' and ' Y ' are respectively
Options
- AAnisole, methyl orange
- BSalicylaldehyde, Phenolphthalein
- CToludine, Phenolphthalein
- DCarbolic acid, Phenolphthalein
Correct answer
D. Carbolic acid, Phenolphthalein
Step-by-step solution
Carbolic acid or phenol reacts with phthalic anhydride in presence of conc. H 2 SO 4 to form phenolphthalein which is used as an acid base indicator. The type of reaction involved is electrophilic substitution reaction. Phenol is ortho-para directing group. Hence, substitution occurs at para position. The phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0.