Indian Forest Service (Mains), Chemistry optional · 2025 · Paper II

Q6(b)(i). Two ester NMR patterns

5 marks
Topic: Principles of spectroscopy and applications in structure elucidation
Question only

Question

Distinguish ethyl acetate and methyl propionate by approximate proton shifts, multiplicities and integrations.

Model answer

The free solution for 2025 answers questions 1, 3, 4, 5 and 8, 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: ¹H and ¹³C NMR: chemical shift, spin–spin coupling and coupling constants, with every Civil Services, IFoS and Geo-Scientist PYQ →

Covers¹H NMR of estersethyl acetate vs methyl propionatechemical shiftOCH₂ quartet

All parts of Question 6

6(a)(i) Photodecarbonylation of thujone5 marks
6(a)(ii) Photochemistry of an amino ketone5 marks
6(a)(iii) Di-pi-methane rearrangement5 marks
6(b)(i) Two ester NMR patterns5 marks
6(b)(ii) A symmetric malonate ester5 marks
6(c)(i) Number- and weight-average molar masses10 marks
6(c)(ii) Syn and anti dihydroxylation5 marks