Q6(c)(i). Structure of C₁₆H₂₅NO from IR and ¹H NMR
An organic compound having molecular formula C₁₆H₂₅NO gave the following IR and ¹H NMR data: IR (cm⁻¹) = 1690; ¹H NMR (CDCl₃, 400 MHz): δ 1.11 (t, J = 7 Hz, 6H), 1.29 (d, J = 7 Hz, 6H), 2.40 (q, J = 7 Hz, 4H), 2.55 (t, J = 7 Hz, 2H), 2.65 (t, J = 7 Hz, 2H), 3.12 (septet, 1H), 7.21 (d, J = 8 Hz, 2H), 7.81 (d, J = 8 Hz, 2H). Determine the structure of the compound.
Model answer
The free solution for 2023 answers questions 1, 2, 3, 5 and 8, the ones picked in its time plan. Question 6 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
- All eight questions of each paper, with the question printed above its answer
- Mechanisms drawn out and labelled on the scheme
- Topic-wise weightage and a topic-wise index
Coversstructure elucidation¹H NMRIR spectroscopyaryl ketonedegree of unsaturation
All parts of Question 6
- 6(a)(i) Energy change of HCl + D₂ → DCl + HD10 marks
- 6(a)(ii) C=O bands of butyric acid, its ethyl ester and its anhydride5 marks
- 6(b)(i) Products A, B and C10 marks
- 6(b)(ii) Tacticity: isotactic, syndiotactic and atactic polymers5 marks
- 6(c)(i) Structure of C₁₆H₂₅NO from IR and ¹H NMR10 marks
- 6(c)(ii) Order of chemical shift of the lettered protons10 marks