Q3(c)(ii). Indole at C-3; inertness of chlorobenzene
Account for the following: (1) Indole undergoes electrophilic substitution to give the 3-substituted product, but not the 2-substituted product. (2) Chlorobenzene does not undergo nucleophilic substitution readily.
Answer in brief
(1) Attack at C-3 gives a cation stabilised by nitrogen without disturbing the benzene ring. (2) The C–Cl bond has partial double-bond character and neither SN1 nor SN2 is open to it.
Part of VKC Basic
Read the key points and the full model answer with VKC Basic
VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.
The full model answer
As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.
Coversindoleelectrophilic substitutionσ-complexchlorobenzenenucleophilic substitutionaryl halide reactivity
All parts of Question 3
- 3(a)(i) Methyl cyanide heated with dilute HCl10 marks
- 3(a)(ii) Bromine addition to cis- and trans-2-butene5 marks
- 3(b)(i) Enone from a methoxy triene5 marks
- 3(b)(ii) Classify the rearrangement at 33 °C5 marks
- 3(b)(iii) Methoxy methyl benzoquinone with butadiene5 marks
- 3(c)(i) Acyl chloride to isocyanate; singlet and triplet nitrene10 marks
- 3(c)(ii) Indole at C-3; inertness of chlorobenzene10 marks