Q13 · CSIR NET Chemistry, December 2017
Paper: CSIR NET December 2017 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Hard
The correct match of the circled protons in Column P with $^{1}\mathrm{H}$ NMR chemical shift ($\delta$ ppm) in Column Q is Column P: I 
II 
III 
Column Q: A. 6.72 B. 16.4 C. $-0.61$
II III Column Q: A. 6.72 B. 16.4 C. $-0.61$(a)I-A; II-B; III-C
(b)I-B; II-A; III-C
(c)I-B; II-C; III-A
(d)I-C; II-B; III-A
Answer
Answer: B ✓ checked by 4AB · confidence medium
Explanation
The inner proton of the paratropic (4n π) dehydroannulene I is strongly deshielded (δ 16.4). The quinone vinyl H (II) is at δ 6.72. The inner proton of the diatropic (4n+2) annulene III is shielded (δ −0.61). I–B, II–A, III–C (b).
Study loop for Organic Spectroscopy