Question

How can $C{{H}_{3}}OH$ be a Lewis acid?

Answer 1

Hint: The answer is based on the fact that the Lewis acids are those substances that can attract an electron pair that is which accepts the non bonding pair of electrons. Compare this fact with methanol and find the answer.

Complete step by step answer:
- In the basic concept of inorganic chemistry, we have come across the different types of acids and bases given by different forms such as Bronsted – Lowry acid – base concept, Lewis acid - base concept and also the Lux – flood concept.
We shall now see what Lewis acids are and how we can determine which compound is the Lewis acid.
- Lewis acids are those that can attract an electron pair that accepts the non bonding pair of electrons.
- In the above given compound that is methanol with the molecular formula $C{{H}_{3}}OH$, the compound has one hydrogen atom attached to the oxygen atom which can be dissociated as ions in the aqueous solution which is as shown below,
\[C{{H}_{3}}OHC{{H}_{3}}{{O}^{-}}+{{H}^{+}}\]
- This above given equilibrium reaction shows that methanol can donate a proton and therefore it acts as a Bronsted – Lowry acid and also the proton from the methanol can accept an electron pair from ammonia to form the ammonium ion and hence acts as Lewis acid. This is as shown below:

Note: Note that the Lewis acids are used as a catalyst in organic reactions where in a metal based Lewis acid acts as an electron pair acceptor which increases the reactivity of the substrate molecule.