Deconstruction of rubber via C–H amination and aza-Cope rearrangement

Abstract

Limited strategies exist for chemical recycling of commodity diene polymers, like those found in tyres^1,2,3. Here we apply C–H amination and backbone rearrangement of polymers to deconstruct these materials into precursors for epoxy resins. Specifically, we develop a sulfur diimide reagent^4,5 that enables up to about 35% allylic amination of diene polymers and rubber. Then, we apply the cationic 2-aza-Cope rearrangement to deconstruct aminated diene polymers. In a model system, we see molecular weight reduction from 58,100 to approximately 400 g mol⁻¹, and aminated post-consumer rubber is deconstructed over 6 hours into soluble amine-functionalized polymers, which can be utilized to prepare epoxy thermosets with similar stiffnesses to commercial bisphenol A-derived resins⁶. Altogether, this work demonstrates the power of C–H amination and backbone rearrangement to enable chemical recycling of post-consumer materials.