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GATE 2023 CY – Question 36

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

A compound $C_{15}H_{16}O_2$ has the following spectra. Its structure is which of the choices shown?

$^1H$ NMR (ppm): 9.16 (s), 6.89 (d, $J=8$ Hz), 6.64 (d, $J=8$ Hz), 1.53 (s).

$^{13}C$ NMR (ppm): 154.7, 140.9, 127.1, 114.4, 40.7, 30.7.

Diagram for GATE 2023 CY question 36
  1. Structure A
  2. Structure B
  3. Structure C
  4. Structure D

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Show answer and explanation

Correct answer: (A) Structure A

Explanation

The 9.16 ppm singlet indicates phenolic OH, and two aromatic doublets indicate equivalent para-substituted rings. A 6H singlet at 1.53 ppm and carbon signals 40.7/30.7 require two equivalent methyls attached to a quaternary bridging carbon. Six carbon environments match symmetric bisphenol A,**option A**; methoxy alternatives would give protons near 3–4 ppm.