How could you distinguish the 1 H NMR spectra of the following compounds?

Nuclear magnetic resonance (NMR) spectroscopy gives information about the structure of the molecule by observing the bonding of carbon and hydrogen atoms.

The characteristics of ${}^1\mathbf{H}$NMR spectrum are shown below:

• Number of signals (chemically non-equivalent)
• Position of signals (chemical shift)
• Shape of the signals (Integration and splitting of peaks).

a)

The structure of the compound A is as follows:

${\mathrm{H}}_3\mathrm{C}-\mathrm{O}-{\mathrm{CH}}_2-\mathrm{O}-{\mathrm{CH}}_3$

Dimethoxy methane

Dimethoxy methane has two non-equivalent protons. They are methyl protons $\left({\mathrm{CH}}_3\right)$and methylene proton $\left({\mathrm{CH}}_2\right)$. So, dimethoxy methane gives two signals.

Methyl protons absorb at 3.30$\mathrm{\delta }$(singlet) and methylene protons absorb at 4.50$\mathrm{\delta }$(singlet) in ${}^1\mathrm{H}$NMR spectrum.

The structure with chemical shift values is as follows:

Structure with chemical shift values

b)

The structure of the compound B is as follows:

${\mathrm{H}}_3\mathrm{C}-\mathrm{O}-{\mathrm{CH}}_3$

methoxymethane

The compound methoxymethane has one non-equivalent proton (methyl proton). So, methoxymethane gives one signal. Methyl protons absorb at 3.30$\mathrm{\delta }$ (singlet) in ${}^1\mathrm{H}$NMR spectrum.

The structure with chemical shift values is as follows:

Structure with chemical shift values

c)

The structure of the compound C is as follows:

1,3-dimethoxy-2,2-dimethylpropane

The compound 1,3-dimethoxy-2,2-dimethylpropane has three non-equivalent protons. They are two methyl protons and one methylene proton. So, 1,3-dimethoxy-2,2-dimethylpropane gives three signals in the ${}^1\mathrm{H}$NMR spectrum.

One methyl proton absorbs at 3.30$\mathrm{\delta }$(singlet) in${}^1\mathrm{H}$NMR spectrum, this is because it is attached to the oxygen atom.

The other methyl proton absorbs at 0.99$\mathrm{\delta }$(singlet) and the methylene protons absorb at 3.79$\mathrm{\delta }$(singlet) in${}^1\mathrm{H}$NMR spectrum.

The structure with chemical shift values is as follows:

Structure with chemical shift values