Question

Write a classification of aliphatic ketones with a suitable example.

Answer 1

On the basis of types of alkyl groups bonded to carbonyl carbon, aliphatic ketones are further classified as simple and mixed ketones.

Simple or symmetrical ketones: The ketones in which both the alkyl groups bonded to carbonyl carbon are identical are called simple ketones or symmetrical ketones.
e.g.

• $$\begin{array}{c}\mathrm{O}\phantom{.......}\\ ||\phantom{.......}\\ \underset{\text{Dimethyl ketone (Acetone)}}{\mathrm{H}{\phantom{A}}_3\mathrm{C}-\mathrm{C}-\mathrm{CH}{\phantom{A}}_3}\end{array}$$
• $$\begin{array}{c}\mathrm{O}\\ ||\\ \underset{\text{Diethyl ketone}}{\mathrm{H}{\phantom{A}}_5\mathrm{C}{\phantom{A}}_2-\mathrm{C}-\mathrm{C}{\phantom{A}}_2\mathrm{H}{\phantom{A}}_5}\end{array}$$

Mixed or unsymmetrical ketones: The ketones in which two alkyl groups bonded to carbonyl carbon are different are called mixed ketones or unsymmetrical ketones.

e.g.

• $$\begin{array}{c}\mathrm{O}\phantom{..}\\ ||\phantom{..}\\ \underset{\text{Ethyl methyl ketone}}{\mathrm{H}{\phantom{A}}_5\mathrm{C}{\phantom{A}}_2-\mathrm{C}-\mathrm{CH}{\phantom{A}}_3}\end{array}$$
• $$\begin{array}{c}\mathrm{O}\phantom{.............}\\ ||\phantom{.............}\\ \underset{\text{Ethyl n-propyl ketone}}{\mathrm{H}{\phantom{A}}_5\mathrm{C}{\phantom{A}}_2-\mathrm{C}-\mathrm{CH}{\phantom{A}}_2-\mathrm{CH}{\phantom{A}}_2-\mathrm{CH}{\phantom{A}}_3}\end{array}$$