Polysubsititution is a major drawback in:
Friedel Carft's alkylation
Reimer Tiemann reaction
Acetylation of aniline
Friedel Carft's acylation
Friedel carft's alkylation
P+O- substituted products are formed (Two e-releasing groups) Reactivity further increases.
In alkylation
as reactivity is continuously increasing due to the substitution of alkyl group in benzene ring no monosubstituted product is formed
P.S. is drawback
Friedel Carft's alkylation
Option 2)Reimer Tiemann reaction
Option 3)Acetylation of aniline
Option 4)Friedel Carft's acylation
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