Q75 · CSIR-NET Chemistry, December 2011
Paper: CSIR-NET December 2011 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Medium
Appropriate ${ }^{\mathrm{1}} \mathrm{H ~ NMR}$ chemical shifts ( $\delta$ ) for the protons A-D for the following compound are 
(a)A-6.8; B-5.7; C-3.9; D-2.1ppm
(b)A-6.8; B-5.7; C-2.1; D -3.9 ppm
(c)A-5.7; B-6.8; C-3.9; D -2.1 ppm
(d)A-5.7; B-6.8; C-2.1; D-3.9 ppm
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
In methyl crotonate the α-H is at δ ≈ 5.7 and the β-H, deshielded by conjugation, at ≈ 6.8–7.0. The allylic CH₃ is at ≈ 1.9–2.1 and the OCH₃ at ≈ 3.7–3.9 (d).
Study loop for Organic Spectroscopy