Question

Bakelite is obtained from phenol by reacting with:
A) ${\left( {C{H_2}OH} \right)_2}$
B) $C{H_3}CHO$
C) $C{H_3}COC{H_3}$
D) $HCHO$

Answer 1

Hint: Bakelite is a phenol or formaldehyde resin which is a highly cross-linked material that has undergone chemical reaction by action of heat, catalyst, UV light, etc.

Complete step by step answer:
1) Bakelite is obtained by the condensation reaction of phenol with formaldehyde.
2) It is a type of cross-link polymer.
3) The schematic representation of the diagram is as follows:
 

4) After further polymerization of the intermediates in presence of formaldehyde, heat, and loss of water molecules will give the product as Bakelite.
5) Hence, the Bakelite is obtained by reaction of phenol with formaldehyde i.e. $HCHO$ which shows option D as a correct choice.

Additional information: Bakelite is a step-growth copolymer. The intermediates formed will further condense eliminating the water molecule and give the novolac as a linear polymer. It further reacts with the formaldehyde in presence of heat which will further transform the linear polymer into the cross polymer which is called Bakelite. Novolac is generally used in paints as an ingredient. Bakelite is generally used for the manufacturing of combs, electric materials, phonograph records, etc. Bakelite is a cross-linked polymer that means it is made of polymeric linkage of covalent or ionic bonds. Bakelite has several important properties such as it can be molded very much quickly which reduces the production time. It is also resistant to electricity and is hailed for its low conductivity. Bakelite is also sometimes used in items such as jewelry materials and radio parts.


Note:
When the phenol and formaldehyde can be reacted in an acidic or basic medium (which in the above reaction basic medium is used) to lead to the formation of Bakelite. It is a condensation type of reaction. Formaldehyde is used in this reaction as there is one carbon present in between two molecules of polymer, and can be used as a trick to solve these types of questions.