Question

Why does methyl $\left( {C{H_3}} \right)$ show electron donation effect?

Answer 1

There are various ways by which an atom can donate electrons i.e. show electron donating effect however in case of Methyl group $\left( {C{H_3}} \right)$ the two primary ways of donation are Inductive effect $\left( { + I} \right)$ and hyperconjugative effect $\left( { + H} \right)$ both of which have different sources of origin one arises due to difference in electronegativity and another arises due to presence of filled sigma bond between Carbon and Hydrogen atom i.e. $C - H$.

Complete step-by-step answer: To explain as to why Methyl group i.e. $\left( {C{H_3}} \right)$ shows electron donation effect we need to study each case step by step:
Case(i): Inductive effect specifically $\left( { + I} \right)$ is one of the dominant ways by which methyl group donates electrons, It arises due to difference in electronegativity of $s{p^3} - C$ atom in $C{H_3}$ and the neighboring group $\left( X \right)$ due to this difference in electronegativity the electron pair in the $(s{p^3})C - X$ bond is polarized to one of the ends of the bond generally for Methyl group to show donation effects the electrons must be more polarized or attracted towards the end near $X$ this polarization enhances electron density on the $X$ site thus establishing the $\left( { + I} \right)$ electron donating effect.
Case(ii): Hyperconjugative effect specifically $\left( { + H} \right)$ arises in the Methyl group due to the presence of filled $C - H$ sigma bonds in Methyl group and empty p or d orbital in the neighboring electron poor group $X$ which leads to a constructive overlap between these two orbitals thus enhancing the electron density over the electron deficient neighbor $X$ due to donating nature of $(s{p^3})C - H$ bond which is a bit weak in nature.

Note: Inductive effect and Hyperconjugative effects are the backbone of General organic chemistry thus we must possess some information on them otherwise we won’t be able to understand organic chemistry and questions of organic chemistry like above.