Indian Forest Service (Mains), Chemistry optional · 2021 · Paper II

Q7(e). State-dependent diene chemistry and photo-Fries rearrangement

5 marks
Topic: Photochemistry
Question only

Question

(i) Give products associated with S₁ and T₁ excitation of buta-1,3-diene. (ii) Complete p-cresol —(PhCOCl, aq. NaOH)→ A —(hν)→ B.

Model answer

The free solution for 2021 answers questions 1, 2, 3, 5 and 6, the ones picked in its time plan. This part is not answered on the site yet. New answers are announced on Telegram.

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Topic notes: organic photochemistry and Norrish reactions, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversphoto-Fries rearrangementsinglet and triplet excitationbutadiene photochemistrycyclobuteneSchotten–Baumann benzoylation

All parts of Question 7

7(a)(i) A beta-chloroamine and sulfonyl chloride5 marks
7(a)(ii) Hydration followed by oxidation5 marks
7(b) Ireland–Claisen rearrangement of an allylic acetate10 marks
7(c)(i) Solvolysis of a tertiary allylic bromide5 marks
7(c)(ii) Ring expansion of vinylcyclobutane5 marks
7(d) Stability of triarylmethyl radicals5 marks
7(e) State-dependent diene chemistry and photo-Fries rearrangement5 marks