Q49 · CSIR-NET Chemistry, June 2016
Paper: CSIR-NET June 2016 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: NMR 1H · Marks: 2 · Difficulty: Hard
In the ${ }^{1} \mathrm{H}$ NMR spectrum of myrtenal, the two methyl groups are expected to display signals at (chemical shift values $\delta$ in ppm) 
myrtenal
myrtenal(a)1.35 (s, 3H) and 5.0 (s, 3H)
(b)0.74 (s, 3H) and 1.33 (s, 3H)
(c)1.22 (s, 6H)
(d)0.07 (s, 6H)
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
The gem-dimethyl bridge of the pinane skeleton gives two singlets, one strongly shielded (≈0.74) and one at ≈1.33 ppm.
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