Question

Account for the following:

Ethylamine is soluble in water, whereas aniline is not.

Answer 1

Ethylamine is soluble in water, due to hydrogen bonding as shown below:

\[\begin{array}{cc}
\ce{H}\phantom{..........................}\ce{H}\phantom{.................}\\
|\phantom{...........................}|\phantom{.................}\\
\ce{{- - - - - -} N-H {- - - - - -} O-H {- - - - - -} N-H {- - - - - -} O-H {- - - - - -}}\\
\phantom{..........}|\phantom{.............}|\phantom{..............}|\phantom{.............}|\phantom{.............}\\
\ce{\underset{Ethylamine}{C2H5}}\phantom{.......}\ce{H}\phantom{.............}\ce{C2H5}\phantom{.........}\ce{H}\phantom{.....}
\end{array}\]

On the other hand, aniline has a large phenyl group and has -I effect due to which the hydrogen bonding with water is reduced. Hence, aniline is insoluble in water.