Question

Identify the structure of an unknown organic compound using nuclear magnetic resonance spectroscopy, given the following NMR spectrum and molecular formula (C7H14O2): Chemical shift (ppm)     Integration0.87 — 3H (s)1.25 — 3H (s)1.45 — 2H (m)2.10 — 2H (t)2.80 — 1H (br s)4.00 — 1H (t)4.20 — 1H (br s)9.70 — 1H (s)

Answer 1

Based on the given NMR spectrum and molecular formula  C7H14O2 , we can deduce the structure of the unknown organic compound as follows:1. The chemical shift at 0.87 ppm  3H, s  and 1.25 ppm  3H, s  indicates the presence of two methyl groups  CH3  in the compound.2. The chemical shift at 1.45 ppm  2H, m  suggests the presence of a methylene group  CH2  adjacent to a heteroatom  O or N .3. The chemical shift at 2.10 ppm  2H, t  indicates another methylene group  CH2  adjacent to a carbonyl group  C=O .4. The chemical shift at 2.80 ppm  1H, br s  suggests the presence of an alcohol group  OH  in the compound.5. The chemical shift at 4.00 ppm  1H, t  indicates a methine group  CH  adjacent to an oxygen atom.6. The chemical shift at 4.20 ppm  1H, br s  suggests the presence of another alcohol group  OH  in the compound.7. The chemical shift at 9.70 ppm  1H, s  indicates the presence of an aldehyde group  CHO  in the compound.Taking all these observations into account, the structure of the unknown organic compound can be deduced as:CH3CH2CH OH CH2C =O CH OH CH3This compound is 2,5-dihydroxyheptanal, which is consistent with the given molecular formula  C7H14O2  and the NMR spectrum.