¹H NMR spectrum of [18]-annulene shows · ABC26OR0705
Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: Organic Spectroscopy – General · Exam: GATE 2000-2022 · Marks: 2 · Difficulty: Easy
$^{1}\mathrm{H}$ NMR spectrum of [18]-annulene shows
(a)Only one peak at $\delta$ 7.2 (18 H)
(b)Only one peak at $\delta$ 5.0 (18 H)
(c)Two peaks at $\delta$ 9.0 (12 H) and $\delta$ $-3.0$ (6 H)
(d)Two peaks at $\delta$ 9.0 (6 H) and $\delta$ $-3.0$ (12 H)
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
[18]-Annulene is aromatic: the 12 outer protons are deshielded (δ ≈ 9.0) and the 6 inner protons shielded by the ring current (δ ≈ −3.0) — (c).
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