UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper III
Q6(h). Citral and citronellal by IR: conjugated and isolated C=O
Question
How can you distinguish between citral and citronellal on the basis of their IR spectra? [structures of citral and citronellal given in the paper]
Answer in brief
Citral (conjugated aldehyde): C=O near 1680 cm⁻¹ and a strong C=C band near 1635 cm⁻¹; citronellal (saturated aldehyde): C=O near 1725 cm⁻¹.
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CoversIR spectroscopycitralcitronellalconjugated carbonylC=O stretching frequency
All parts of Question 6
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- 6(g) Aromatic proton shifts: NO₂, COOH and CF₃ as para substituents4 marks
- 6(h) Citral and citronellal by IR: conjugated and isolated C=O4 marks
- 6(i) 3-Methyl- and 4-methylpentan-2-one by mass spectrometry4 marks
- 6(j) 4-Bromobenzoyl chloride to 4-bromoaniline: Lossen rearrangement4 marks