Q14 · CSIR-NET Chemistry, December 2016

Paper: CSIR-NET December 2016 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Medium

$^{1}\mathrm{H}$ NMR spectrum of an organic compound recorded on a 500 MHz spectrometer showed a quartet with line positions at 1759, 1753, 1747, 1741 Hz. Chemical shift ($\delta$) and coupling constant (Hz) of the quartet are
(a)3.5 ppm, 6 Hz
(b)3.5 ppm, 12 Hz
(c)$3.6 \mathrm{ppm}, 6 \mathrm{Hz}$
(d)$3.6 \mathrm{ppm}, 12 \mathrm{Hz}$
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
Centre of the quartet = (1759 + 1741)/2 = 1750 Hz; at 500 MHz that is 1750/500 = 3.5 ppm. Line spacing = 1759 − 1753 = 6 Hz = J.

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