An unknown compound C (molecular formula ${\mathbf{C}}_{\mathbf{4}}{\mathbf{H}}_{\mathbf{8}}{\mathbf{O}}_{\mathbf{3}}$ ) exhibits IR absorption at 3600-2500 and 1734 localid="1649052784484" ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$, as well as the following ${}^{\mathbf{1}}\mathbf{H}$NMR spectrum. What is the structure of C?

The IR spectroscopy determines the vibrational modes of the molecule. It helps to determine the type of the functional group in a molecule and the molecular structure of the molecule.

${}^1\mathrm{H}$NMR is used to determine the structure of the molecules. It is also determines the number and the location of the hydrogen atoms in the given organic compound.

One can determine the structure of the compound C based on the IR and ${}^1\mathrm{H}$NMR data:

The compound C with the molecular formula ${\mathrm{C}}_4{\mathrm{H}}_8{\mathrm{O}}_3$has one degree of unsaturation. The IR absorption takes place at 3600-2500 ${\mathrm{cm}}^{-1}$, which corresponds to the O-H absorption, and the 1734 ${\mathrm{cm}}^{-1}$corresponds to the carbonyl (C=O) absorption frequency.

The ${}^1\mathrm{H}$NMR datashows a triplet at 1.2 ppm for the three hydrogen atoms that belong to a methyl group adjacent to two hydrogens. There is also a quartet at 3.6 ppm for two hydrogen atoms that are adjacent to three other hydrogens.

There is one singlet at 4.1 ppm for two hydrogen atoms, and one singlet at 11.3 ppm for one hydrogen of the carboxylic group.

According to the above spectroscopic data, the structure of the compound C is shown below:

Ethoxy acetic acid