Question

Give the structure that corresponds to the following molecular formula and 1H NMR spectrum: The magenta numbers in the spectrum are the relative integrals in arbitrary units.

Answer 1

Concepts and reason

¹H NMR Spectroscopy:

Nuclear magnetic resonance spectroscopy is one of the techniques in the analytical chemistry that is widely used to determine the purity of sample and to predict the structure of the organic compounds.

The spectroscopy is phenominal that is observed when frequency of nuclei of atoms (sample) resonates with frequency of rotating magnetic field.

Spectroscopy determines the different types of hydrogens (chemically non-equivalent hydrogens) present in a molecule.

Fundamentals

¹H NMR Spin-Spin Coupling Patterns:

Number of neighboring hydrogens (chemically non-equivalent) n	Number of peaks ()	Splitting Name	Peak heights ratio
0	1	Singlet
1	2	Doublet
2	3	Triplet
3	4	Quartet

The formula to calculate the degree of unsaturation:

The spectral data is given below:

Chemical shift	Multiplicity
Around 0.9ppm	triplet
Around 1.38ppm	quartet
Around 1.42ppm	singlet

Chemical shift – 1.42ppm: The spectra shows quartet at 1.42ppm is due to the splitting of three hydrogens attached to carbon and there are three identical methyl groups.

Chemical shift – 1.38ppm: The singlet peak is observed at 1.38ppm disappear after shaking with proton at group of tertiary alcohol.

Chemical shift – 0.9ppm: The spectra shows triplet at 0.9ppm is due to the splitting of two hydrogens attached to carbon shows this peak and three identical ethyl groups.

Therefore, the compound has one alcoholic group and three identical groups attached to the tertiary carbon atom.

The structure of the compound with assignment of chemical shift values is given below:

Ans:

The structure for the given organic compound is