Q13-11P - Organic Chemistry (Mcmurry)

Question

The integrated 1H NMR spectrum of a compound of the formula ${\mathbf{C}}_4{\mathbf{H}}_{10}\mathbf{O}$is shown in Figure. Propose a structure.

Step-by-Step Solution

Answer

The possible structure is  ${\text{CH}}_{\text{3}}{\text{-CH}}_{\text{2}}{\text{-O-CH}}_{\text{2}}{\text{-CH}}_{\text{3}}$.

Step-by-Step Solution Step 1: Degree of unsaturation

The degree of unsaturation gives the total number of $\mathrm{\pi }$ bonds in the system.

DOU = $\left\{\mathrm{C}+1-\left(\frac{\mathrm{H}}{2}\right)+\left(\frac{\mathrm{N}}{2}\right)\right\}$

          = $4+1-\frac{\text{10}}{\text{2}}$

          = 5-5

          =0

It indicates that the given compound is saturated.

Step 2: Spectral information

The given data show that a given organic compound has two types of protons. One set of protons shows a triplet which means an adjacent carbon atom shows two identical protons.

Also, one set shows a quartet which means it adjacent carbon atom shows four identical hydrogen atoms.

So the possible structure is ${\mathrm{CH}}_3-{\mathrm{CH}}_2$

Step 3: Effect of an electronegative group on chemical shift

In the above example, oxygen is electronegative so it causes deshielding because of that proton shows a chemical shift at higher ppm.

Possible structure is ${\text{CH}}_{\text{3}}{\text{-CH}}_{\text{2}}{\text{-O-CH}}_{\text{2}}{\text{-CH}}_{\text{3}}$.