Q69E - Organic Chemistry (Mcmurry)

Question

The proton NMR spectrum is shown for a compound with the formula ${\mathbf{C}}_{\mathbf{5}}{\mathbf{H}}_{\mathbf{9}}{\mathbf{NO}}_{\mathbf{4}}$. The infrared spectrum displays strong bands at 1750 ${\mathbf{cm}}^{\mathbf{-}}$ and 1562 ${\mathrm{cm}}^{-}$ and a medium-intensity band at 1320 ${\mathrm{cm}}^{-}$. The normal carbon-13 and the DEPT experimental results are tabulated. Draw the structure of this compound.

Step-by-Step Solution

Answer

Structure of the compound is:

Step 1: Degree of unsaturation

It is also known as the index of hydrogen deficiency it is used to determine the molecular formula of an organic compound by determining the total number of rings and pi bonds.

As per the given molecule have two unsaturation due to the double bonds, ring or triple bond is present.

Step 2: Structure elucidation from IR spectra

As the given data the peak at 1750 ${\mathrm{cm}}^{-}$ is observed to show the presence of an ester group.

The peak at 1562 and 1370 ${\mathrm{cm}}^{-1}$ shows the presence of the nitro group in the compound.

Step 3: 13 C   NMR

Carbon-13 nuclear magnetic resonance is a technique similar to the NMR which is used to identify the carbon from the organic molecules or from the organometallic compounds like hydrogen is detected in NMR but it’s only sensitive to carbon-13, not carbon-12.

Step 4: Structure elucidation of the compound as per data

Per given DEPT table show that the DEPT 135 is positive the presence of methylene group and DEPT at 90 shows the presence of CH group and the peak is observed at 4.76 due to the next oxygen atom attached to carbon and the peak at 4.50 showing that the carbon is attached to the nitro group as shown below:

Step 5: Structure of the compound

As per all the data given the possible structure of the compound is 2-nitro propyl acetate as shown below: