Codex @codex  0

 Incoming links: Monomer functionality

Past exam of the chemistry B course of the University of Cambridge / 2023 / Paper 2 / B9 / b / i / Solution 2026-10-20

First hydrolyse both Si–Cl groups to give a silanol of monomer functionality two, then condense Si–OH groups to form the Si–O–Si backbone:

R_{2} SiC l_{2} + 2 H_{2} O ⟶ R_{2} Si (OH)_{2} + 2HCl,

(1)

\equiv Si - OH + HO - Si \equiv ⟶ \equiv Si - O - Si \equiv + H_{2} O .

(2)

monomer functionality two favours chains, with cyclic oligomers also possible. Removal of condensation products or equilibration under appropriate conditions favours high molar mass. The hydrolysis and condensation can overlap in a one-pot process; the equations distinguish their chemical functions rather than requiring isolation of every silanediol.

 Read the full article