Polysubstitution is a major drawback in:
- Reimer Tiemann reaction
- Friedel Craft's alkylation
- Acetylation of aniline
- Friedel Craft's acylation
Solution

In Friedel crafts alkylation product obtained is more activated due to the activating nature of the alkyl group and hence poly substitution will take place.
Asked in: JEE Main 2019 (08 Apr Shift 2)