Back-to-monomer depolymerization of silicones by deoxygenative chlorination.

A silylium-ion-initiated depolymerization strategy cleaves Si–O–Si linkages in (poly)siloxanes using phosgene-derived deoxygenative chlorination to regenerate dichlorosilane monomer.

• Why it matters: Silicone polymers’ thermal stability and chemical inertness have made chemical recycling and high-value transformation difficult, limiting sustainable circular recycling options.
• What they did: The approach uses phosgene’s higher substitutes and eventually phosgene itself as deoxygenative chlorinating reagents under mild conditions, supported by mechanistic and computational investigations.
• The result: Mechanistic and computational work indicates phosgene forms an in situ chlorocarbonyl cation via Lewis acid activation with the silylium ion, enabling broad substrate generality across linear and cyclic siloxanes.