Question

Number of compounds from the following which cannot undergo Friedel-Crafts reactions is :____
toluene, nitrobenzene, xylene, cumene, aniline, chlorobenzene, m-nitroaniline, m-dinitrobenzene

Answer 1

Friedel-Crafts reactions require an aromatic compound and an electrophile, facilitated by a Lewis acid catalyst (e.g., AlCl$_3$). However,
certain compounds cannot undergo Friedel-Crafts reactions due to deactivating groups or coordination issues with the catalyst.
** Toluene, xylene, and cumene**: These are activated aromatic compounds and can undergo Friedel-Crafts reactions.
** Chlorobenzene**: Chlorine is an electron-withdrawing group but is ortho/para-directing; hence it can still undergo Friedel-Crafts reactions.
** Nitrobenzene, m-nitroaniline, m-dinitrobenzene**: Nitro groups are strongly deactivating, making the aromatic ring unreactive for Friedel-Crafts reactions.
** Aniline**: The amino group ($-\text{NH}_2$) coordinates with the Lewis acid catalyst (AlCl$_3$), deactivating the ring.
Compounds that cannot undergo Friedel-Crafts reactions:
Nitrobenzene, aniline, m-nitroaniline, m-dinitrobenzene (4 compounds).
Final Answer: (4)

Answer 2

Friedel-Crafts reactions require an aromatic compound and an electrophile, facilitated by a Lewis acid catalyst (e.g., AlCl$_3$). However,
certain compounds cannot undergo Friedel-Crafts reactions due to deactivating groups or coordination issues with the catalyst.
** Toluene, xylene, and cumene**: These are activated aromatic compounds and can undergo Friedel-Crafts reactions.
** Chlorobenzene**: Chlorine is an electron-withdrawing group but is ortho/para-directing; hence it can still undergo Friedel-Crafts reactions.
** Nitrobenzene, m-nitroaniline, m-dinitrobenzene**: Nitro groups are strongly deactivating, making the aromatic ring unreactive for Friedel-Crafts reactions.
** Aniline**: The amino group ($-\text{NH}_2$) coordinates with the Lewis acid catalyst (AlCl$_3$), deactivating the ring.
Compounds that cannot undergo Friedel-Crafts reactions:
Nitrobenzene, aniline, m-nitroaniline, m-dinitrobenzene (4 compounds).
Final Answer: (4)