GATE 2026 CY – Question 57

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 · Numerical answer

Consider the following reaction sequence, where A and B are the major products. In proton-decoupled 13C NMR spectra, the total number of carbon signals observed for A and B is ______ (in integer).

Toluene and succinic anhydride followed by reduction, cyclization, methylation and dehydrogenation.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: 16 to 16

Explanation

The official total is 16 carbon signals. Count the carbon environments of both major products after completing the sequence. The provisional total of 15 assumed a symmetric dimethylnaphthalene product with six environments; that final symmetry assignment was incorrect.

Official GATE 2026 answer key: https://gate2026.iitg.ac.in/doc/download/2026/Keys/CY_Keys.pdf