Q6(g). Three isomeric esters C₄H₈O₂ from ¹H NMR
Three isomeric compounds A, B and C have molecular formula C₄H₈O₂. All of these show a strong absorption at 1730 cm⁻¹ in their IR spectra. Their ¹H NMR spectra are as follows: A: δ 1.2 (3H, t); 2.35 (2H, q); 3.7 (3H, s). B: δ 1.2 (3H, t); 2.0 (3H, s); 4.1 (2H, q). C: δ 1.0 (3H, t); 1.65 (2H, m); 4.1 (2H, t); 8.0 (1H, s). Assign suitable structures to A, B and C.
Answer in brief
A = methyl propanoate, CH₃CH₂COOCH₃; B = ethyl ethanoate (ethyl acetate), CH₃COOCH₂CH₃; C = propyl methanoate (propyl formate), HCOOCH₂CH₂CH₃.
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Covers1H NMRester isomerschemical shiftspin–spin splittingC4H8O2
All parts of Question 6
- 6(a) Reactivity of four alkenes towards electrophilic addition4 marks
- 6(b) Quaternisation, then Sommelet–Hauser rearrangement4 marks
- 6(c) Woodward–Fieser rules: three dienones4 marks
- 6(d) Carbonyl stretching bands of three lactones4 marks
- 6(e) Epoxidation of cholesterol with a peroxy acid4 marks
- 6(f) Norrish Type II reaction of two aryl alkyl ketones6 marks
- 6(g) Three isomeric esters C₄H₈O₂ from ¹H NMR6 marks
- 6(h) McLafferty rearrangement in a ketone, an acid and an ester6 marks
- 6(i) Stretching frequencies of six single bonds2 marks