Q7(c)(i). Two isomeric esters C₁₀H₁₂O₂
Given below are the NMR spectral characteristics of two isomeric compounds with molecular formula C₁₀H₁₂O₂: (1) ¹H NMR: δ 2.0 (3H, s), 2.93 (2H, t), 4.3 (2H, t), 7.3 (5H, s); (2) ¹H NMR: δ 1.23 (3H, t), 3.72 (2H, s), 4.13 (2H, q), 7.3 (5H, s). Both compounds exhibit a peculiar peak in the IR spectrum at 1730 cm⁻¹. Deduce the structures of these two compounds.
Model answer
The free solution for 2024 answers questions 1, 3, 5, 6 and 8, the ones picked in its time plan. Question 7 is answered in full in the Chemistry Paper II, 2021 to 2025 book, with every part of every paper.
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UPSC Civil Services (Main) Chemistry Paper II: Model Answers 2021 to 2025
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Covers¹H NMR structure deductionisomeric estersC₁₀H₁₂O₂IR ester carbonylspin–spin splitting
All parts of Question 7
- 7(a) λmax of three dienones by Woodward–Fieser rules15 marks
- 7(b) X, Y and Z from an N-Boc piperidine aldehyde15 marks
- 7(c)(i) Two isomeric esters C₁₀H₁₂O₂10 marks
- 7(c)(ii) Fragment ions m/z 58 and m/z 9210 marks