Q.Describe the structure of bakelite and explain how a three-dimensional cross-linked network is built up from phenol and formaldehyde.

Formaldehyde first adds to phenol at the ring positions ortho and para to the $-\text{OH}$ group (activated positions), giving hydroxymethylphenols; under controlled conditions these condense further with additional phenol molecules, eliminating water, to build a linear, low-molecular-weight prepolymer (novolac or resole, depending on the phenol:formaldehyde ratio and catalyst). On further heating, with additional formaldehyde and a hardener, the remaining reactive $-\text{CH}_2\text{OH}$ groups and free ring positions condense extensively with NEIGHBOURING chains, forming numerous methylene ($-\text{CH}_2-$) bridges linking many phenol rings together in multiple directions, not just end to end. This builds up a rigid, three-dimensional, cross-linked network rather than a simple linear chain; once cured, the dense cova …

Trace the reaction in two stages: linear prepolymer formation (limited condensation) followed by extensive cross-linki …

Describing bakelite as a simple linear chain like nylon or terylene, missing that its defining feature is cross-li …