Question

Write down the chemical equation for the preparation of Bakelite from formaldehyde?

Answer 1

Hint : The reaction between formaldehyde (HCHO) and phenol $\left( {{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH}}} \right)$ leads to the formation of intermediates which undergo reaction with each other to form a Novolac resin. This resin is further heated with formaldehyde to produce a cross linked polymer, i.e., Bakelite.

Complete step by step solution :
The molecular formula of formaldehyde is HCHO. When formaldehyde reacts with phenol having molecular formula of ${{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH}}$ in the presence of any acid or base catalyst, this leads to the formation of o-hydroxymethyl phenol and/ or p-hydroxymethyl phenol derivatives (monoethylol phenols) which act as intermediates.

When two monoethylol phenols react with each other, Novolac resin is produced by the elimination of a water molecule. Novolac resin is also referred to as phenol-formaldehyde resin.

The Novolac resin is further heated in the availability of formaldehyde which leads to the formation of a cross linked polymer which is referred to as Bakelite.

Additional Information: Bakelite is an infusibe solid mass. It is a non-conductive material and hence acts as a good insulator. Therefore it is utilized for the formation of a number of daily used products such as combs, switches, handles of different utensils. It is a thermosetting plastic.

Note : Sometimes, you can get confused between Novolac and Bakelite. Thus the difference between Bakelite and Novolac is that Bakelite is a cross linked polymer or a branched structure which is produced by formaldehyde cross linking to produce an infusible solid mass whereas Novolac is a linear structure produced by the condensation reaction between phenol $\left( {{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH}}} \right)$ and formaldehyde (HCHO).