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

Q6(b)(ii). A symmetric malonate ester

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

Question

Identify C₁₁H₂₀O₄ with reported signals 4.18 (q), 1.92 (t), 1.24 (q), 0.82 (t) ppm.

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 →

CoversNMR structure determinationdiethyl diethylmalonatemalonate esterC₁₁H₂₀O₄

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