Inductive effect

In the previous post I gave you some compounds and asked you to arrange them in the order of their acidity. They were CH₃COOH, Br CH₂COOH, ICH₂COOH, ClCH₂COOH and FCH₂COOH, let’s examine them.

To compare their acidity, we have to look inside their structure. Let’s draw the Kekulé structure of these compounds. Now you must be able to find out the acidic H in these molecules. When you compare all these molecules you will find that each has one different electronegative element. This electronegative element is connected to acidic H through a series of sigma bonds. As you know that the electron density of a sigma bond is maximum, along its axis, so it will be easier for electronegative element to pull electron density from O-H bond. This withdrawal of electron density is called the inductive effect. This makes the O-H bond electron deficit and so molecule easily gives off its proton (H⁺).

Inductive Effect and Acidity of molecule

 The same inductive effect shares the burden of extra negative charge of O when conjugate base is which increases the stability of the base. Stable bases are weak bases which rarely accept proton, so its conjugate acid is stronger. Or as we say; the stable structures are formed faster so the acid gives off proton faster because it will produce a more stable conjugate base.

Inductive effect

Strength of Inductive effect depends on the power of the element to pull electron density. It means more electronegative element creates stronger inductive effect which increases the acidity of molecule.

I hope you have understood the Inductive effect and how it affects the acidity of the molecule. Let’s compare the acidity of CH₃CH₂CHClCOOH and CH₃CHClCH₂COOH.

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