Question

Explain structural isomerism in organic compound.​

Answer 1

Answer:

A structural isomer, also known as a constitutional isomer, is one in which two or more organic compounds have the same molecular formulas but different structures. The two molecules below have the same chemical formula, but are different molecules because they differ in the location of the methyl group.

Answer 2

Isomerism in organic compounds

The unique feature of the carbon-carbon (c - c) bonding has also let to the formation of compounds that can have the same molecular formula, but different structures. This phenomenon of different structural formula of the same molecule, giving rise to different properties of compounds, is called isomerism. Such compounds with the same molecular formula are called

isomers of one another. Another common example of isomerism is butane, where there are following two possible structures for the same molecular formula $\sf C_4H_{10}$

Two structural isomers of butane :

$\boxed{ \begin{array}{cc} \large \sf {\normalsize H} - \overset{ \normalsize H}{ \overset{ \normalsize|}{\underset{\normalsize H}{\underset{ \normalsize|}{\normalsize C }}}}- \small{ \underset{\normalsize H}{\underset{ \normalsize|}{\overset{\normalsize H}{ \overset{ \normalsize| }{\normalsize C}}}} \normalsize- \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize-{}} \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize- {\normalsize H} \\ \\ \\ \\ \\ \pink{\underset{ \pmb{ \sf C_4H_{10}}}{{{\pmb { \sf{Butane}}}}}}\end{array}}&\boxed{ \begin{array}{cc} \large \sf{\normalsize H} - \overset{ \normalsize H}{ \overset{ \normalsize |}{\underset{\normalsize H}{\underset{ \normalsize|}{\normalsize C }}}}\! - \!\!\!\!\!\!\!\! \small { \underset{\normalsize \quad CH_{3} }{\underset{\!\!\!\! \begin{array}{c|c} \\ \\ \\ \\ \\ \end{array}}{\overset{\normalsize H}{ \overset{ \normalsize| }{\normalsize C}}}}\!\!\!\!\!\!\!\!\!\normalsize- \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize- {\normalsize H}} \\ \\ \\ \\ \pink{\underset{ \pmb{ \sf C_4H_{10}}}{{{\pmb { \sf{ Iso-Butane}}}}}}\end{array}}$

Three Structural isomers of pentane :

$\underset{ \footnotesize \sf Pentane}{ \underset{}{ \large \sf {\normalsize H} - \overset{ \normalsize H}{ \overset{ \normalsize|}{\underset{\normalsize H}{\underset{ \normalsize|}{\normalsize C }}}}- \small{ \underset{\normalsize H}{\underset{ \normalsize|}{\overset{\normalsize H}{ \overset{ \normalsize| }{\normalsize C}}}} \normalsize- \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize-} \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize- \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize-{\normalsize H}}}& \underset{ \footnotesize\sf 2-Methyl \: butane } {\underset{}{{\large \sf {\normalsize H} - \overset{ \normalsize H}{ \overset{ \normalsize|}{\underset{\normalsize H}{\underset{ \normalsize|}{\normalsize C }}}}- \small{ \underset{\normalsize H}{\underset{ \normalsize|}{\overset{\normalsize H}{ \overset{ \normalsize| }{\normalsize C}}}} \normalsize- \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize \qquad \qquad \qquad CH_{3}{_{ \tiny{\bf (Methyl \: Group)}}}}{\underset{\!\!\!\!\!\begin{array}{c |c} \\ \\ \\ \\ \end{array}}{\normalsize C }}}}\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\normalsize-} \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize- \normalsize H }}}&& \underset{ \footnotesize \sf 2,2-Dimethyl \: propane}{\underset{}{\sf {\normalsize H} - \overset{ \normalsize H}{ \overset{ \normalsize|}{\underset{\normalsize H}{\underset{ \normalsize|}{\normalsize C }}}}-\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\! \: { \underset{ \quad \quad \qquad \qquad \normalsize CH_{3}{_{ \tiny{\bf (Methyl \: Group)}}}}{\underset{ \!\!\!\!\begin{array}{c |c} \\ \\ \\ \\ \end{array}}{\overset{{\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\overset{\normalsize \: \qquad \qquad \qquad CH_{3}{_{ \tiny{\bf (Methyl \: Group)}}}}{{\overset{\begin{array}{c |c} \\ \\ \\ \\ \\ \end{array}}{ }}}}\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!}{{\normalsize C}}}} \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\normalsize- \overset{\normalsize H}{ \overset{\normalsize|}{\underset{\normalsize H}{\underset{\normalsize |}{\normalsize C }}}}\normalsize-} \normalsize H }}$

Isomers can have different functional groups.

$\underset{ \sf \footnotesize Propanone \: (ketone) }{ \underset{}{ \sf CH_3 - \overset{ \normalsize O}{\overset{ \normalsize \|}{C}}- CH_3}}& \underset{ \footnotesize\sf Propanone (aldehyde)}{ \underset{}{ \sf CH_3 - CH_2 - \overset{ \normalsize O}{\overset{ \normalsize \|}{C}}- H }}$