How does a methyl group applies a "+inductive effect"?

1 Answer
Dec 5, 2017

Here is my explanation.

Explanation:

We say that a #"C-H"# bond is "nonpolar" because the difference in electronegativities of the two atoms is so small.

However, the difference is not zero.

The electronegativity of #"C"# is 2.55, while that of #"H"# is 2.20.

Thus, #ΔEN = 0.35#. This corresponds to about 3 % ionic character in a #"C-H"# bond, with the carbon atom being the negative end of the bond dipole.

+I Effect
(Adapted from SlideShare)

Thus, the carbon atom tends to "push" electron density to the neighbouring atom.

This is an electron-releasing effect that we call the +I effect.

The effect is small, but it is a measurable effect.