Q54 · CSIR-NET Chemistry, December 2018
Paper: CSIR-NET December 2018 · Subject: Organic Chemistry · Chapter: Organic Spectroscopy · Topic: Combined Structure Elucidation · Marks: 2 · Difficulty: Hard
Partial spectroscopic data is given below for an organic compound (i) 4 signals between $\delta \mathrm{120} - \mathrm{150} ~ p p m$ in ${ }^{\mathrm{13}} \mathrm{C} ~ N M R$ spectrum (ii) 2 doublets between $\delta$ 6.8-8.5 ppm in ${ }^{\mathrm{1}} \mathrm{H ~ NMR}$ spectrum (iii) An absorption band at $\mathrm{1724 ~ cm}^{- \mathrm{1}}$ in IR spectrum The structure of the compound is
(a)
(b)
(c)
(d)
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
A para-disubstituted ring gives 4 aromatic carbons and 2 doublets. 1724 cm⁻¹ is a conjugated aryl ester (an aryl alkanoate would absorb near 1760): ethyl 4-methylbenzoate (b).
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