UPSC Combined Geo-Scientist, Mains · 2018 · Mains Paper III
Q10(a). Phenolic OH band shapes
Question
Why is BHT OH a sharp band near 3600 cm⁻¹ while paracetamol gives a broad band around 3300–3000 cm⁻¹?
Answer in brief
BHT has a sterically shielded, relatively free OH; paracetamol forms an extended hydrogen-bonding network.
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CoversPhenolic OH band shapesInfrared spectroscopy
All parts of Question 10
- 10(a) Phenolic OH band shapes5 marks
- 10(b) Cyclic ether identification5 marks
- 10(c)(i) Most downfield proton2 marks
- 10(c)(ii) Highest carbonyl frequency2 marks
- 10(c)(iii) Odd nominal molecular mass2 marks
- 10(c)(iv) Most upfield carbon2 marks
- 10(c)(v) Longest-wavelength diene band2 marks
- 10(d) Phenethyl alcohol spectra10 marks