Q8(e). A fragrant aromatic aldehyde
Assign the fragrant solid C₈H₈O₃ from the following data. UV: 275, 292, 295 nm. IR (cm⁻¹): 3250, 3060, 2950, 2840, 2760, 2720, 1700, 1600, 1580, 1500, 1250, 1050. ¹H NMR: δ 5.75 (s), 7.1 (d, 8 Hz), 7.1 (dd, 2 and 8 Hz), 8.05 (s), 9.80 (s). MS (m/z): 152, 151, 123, 137, 109, 89.
Answer in brief
Vanillin, 4-hydroxy-3-methoxybenzaldehyde, is the likely intended structure; the printed proton list omits the expected methoxy signal.
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Coversvanillinstructure elucidationcombined spectral problemaromatic aldehydeC8H8O3
All parts of Question 8
- 8(a) N–H identification in hexamethylenediamine5 marks
- 8(b) Aromatic proton coupling constants5 marks
- 8(c) Matching mass-spectral behaviour10 marks
- 8(d) Diphenyl ether and its mass fragments10 marks
- 8(e) A fragrant aromatic aldehyde10 marks