Q58 · CSIR-NET Chemistry, June 2018
Paper: CSIR-NET June 2018 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Medium
The correct match of protons in column A with the ${ }^{1} \mathrm{H}$ NMR chemical shifts in column B for the product of the following reaction is 
| Column A | Column B |
|---|---|
| P. $\mathrm{H}_{A}$ | 1. -0.3 |
| Q. $\mathrm{H}_{B}$ | 2. 5.1 |
| R. $\mathrm{H}_{1}$ and $\mathrm{H}_{7}$ | 3. 6.4 |
| S. $\mathrm{H}_{2-6}$ | 4. 8.5 |
(a)P-2, Q-1, R-3, S-4
(b)P-1, Q-2, R-4, S-3
(c)P-4, Q-1, R-3, S-2
(d)P-2, Q-4, R-1, S-3
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
Homotropylium ion: the ring current shields the inner methylene proton to δ −0.3 and leaves the outer at 5.1; H1/H7 at 6.4 and H2–H6 at 8.5. With HA the exo and HB the endo proton: P-2, Q-1, R-3, S-4 (a).
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