The GATE Grind

GATE 2025 CY – Question 42

Organic Chemistry · Experimental Techniques in Organic Chemistry: Optical rotation (polarimetry). Application of various chromatographic techniques such as thin-layer, column, HPLC and GC. Applications of UV-visible, IR, NMR spectroscopy and Mass spectrometry in the structural determination of organic molecules. · 2 marks · Multiple choice

Compound K has a strong IR band at 1680 cm−1. Its $^1$H NMR data: $\delta$ (ppm) 7.30 (d, J = 7.2 Hz, 2H), 6.8 (d, J = 7.2 Hz, 2H), 3.8 (septet, J = 7.0 Hz, 1H), 2.2 (s, 3H), 1.9 (d, J = 7.0 Hz, 6H). Its correct structure is

Four candidate aromatic structures for the IR and NMR data.
  1. Option A in the figure
  2. Option B in the figure
  3. Option C in the figure
  4. Option D in the figure

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) Option C in the figure

Explanation

Two aromatic 2H doublets indicate para substitution. The septet and 6H doublet identify an isopropoxy group, and the 3H singlet at 2.2 ppm identifies an acetyl methyl. These features fit C.