LAUSR

The ability to selectively introduce diverse functionality onto hydrocarbons is of substantial value in the synthesis of both small molecules and polymers. Herein, we report an approach to aliphatic carbon–hydrogen bond diversification using radical chain transfer featuring an easily prepared O-alkenylhydroxamate reagent, which upon mild heating facilitates a range of challenging or previously undeveloped aliphatic carbon–hydrogen bond functionalizations of small molecules and polyolefins. This broad reaction platform enabled the functionalization of postconsumer polyolefins in infrastructure used to process plastic waste. Furthermore, the chemoselective placement of ionic functionality onto a branched polyolefin using carbon–hydrogen bond functionalization upcycled the material from a thermoplastic into a tough elastomer with the tensile properties of high-value polyolefin ionomers. Description A clean break for C–H bonds Carbon–hydrogen (C–H) bonds are ubiquitous in pharmaceuticals and plastics but are difficult to transform. Fazekas et al. report a versatile reagent that strips hydrogen without immediately trapping the carbon. Heating or photolysis of the reagent produces a pair of radicals, one of which rapidly cleaves a C–H bond while the other remains comparatively inert. A wide variety of other radical sources can then intercede to form carbon–halogen, carbon–carbon, and carbon–sulfur bonds. A two-step upcycling sequence that added imidazolium groups to postconsumer polyethylene foam produced a potentially valuable ionomer. —JSY A radical reagent strips hydrogen atoms from organic molecules and plastics to enable their broad functionalization.