Chemistry - Aromatic Hydrocarbon Question with Solution | TestHub

Question Explanation:

The question asks to identify which of the four given benzene derivatives does not undergo a Friedel Crafts (Alkylation or Acylation).

Concept:

This question is based on the Friedel-Crafts Reaction (EAS reaction). 

Solution:

The Friedel-Crafts reaction is an EAS that typically fails for two reasons:

1. Presence of a strong deactivating group (-NO₂ , -CN, -COOH etc.)

2. Presence of a strong activating group (-NH₂ , -NHR, -OH)

Aniline forms unreactive salts with Lewis Acid catalysts like AlCl₃ . Aniline forms C₆H₅NH₂⁺ AlCl₃^- , a strong deactivating group

While the trimethylphenylammonium ion

is already a strong deactivating group (-NMe₃⁺ )