UPSC Civil Services (Mains), Chemistry optional · 2023 · Paper II

Q2(c)(i). Acetolysis of 2-(cyclopent-3-enyl)ethyl tosylate

10 marks
Topic: Substitution reactions
Answered

Question

Write the structure of the product of the above reaction (AcOH, heat; solvolysis) and provide suitable mechanism. [structure of 2-(cyclopent-3-enyl)ethyl tosylate given in the paper]

Answer in brief

Product: exo-2-norbornyl acetate (exo-bicyclo[2.2.1]heptan-2-yl acetate), formed by π-participation.

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.

See what is included Already a member? Sign in

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.

The handwritten model answer pages open with the VKC plan.

Read the whole 2023 solution 2023 question paper

Topic notes: nucleophilic substitution (SN1, SN2, SNi, neighbouring group participation, solvent effects, rearrangement), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversacetolysisπ-participationnon-classical carbocation2-norbornyl cationsolvolysis

All parts of Question 2

2(a)(i) Aromatic, antiaromatic or non-aromatic by the Hückel rule5 marks
2(a)(ii) Primary and secondary kinetic isotope effects5 marks
2(a)(iii) Enolates of butan-2-one: NaOMe versus LDA5 marks
2(b)(i) Hydrolysis of bis(2-chloroethyl) sulfide and of 1,5-dichloropentane5 marks
2(b)(ii) Both glycosyl bromides give the β-glycoside5 marks
2(b)(iii) Ketene, hν, then cis-but-2-ene10 marks
2(c)(i) Acetolysis of 2-(cyclopent-3-enyl)ethyl tosylate10 marks
2(c)(ii) Indole: electrophilic substitution at C-3, not C-25 marks