Oxyfunctionalization of polystyrene by hydrogen peroxide using non-heme iron catalysts

• Non-heme iron complexes catalyze C–H activation of small molecule alkanes by H2O2.
• Low molecular weight polystyrene is oxyfunctionalized by H2O2 utilizing two such iron complexes.
• IR and NMR spectroscopy indicate that the resulting polymer contains keto and hydroxyl groups.
• GPC analyses indicate that little C–C cleavage or cross-linking occur under appropriate conditions.
• DSC experiments demonstrate a significant increase in Tg of the products.

The non-polar nature of polystyrene (PS) permits this material to be used in a variety of industrial and household applications. This same property also limits its interactions with polar materials while its stability renders it slow to undergo biological degradation, making polystyrene an environmental concern. That said, the introduction of polar groups along the backbone could increase its compatibility with polar materials as well as possibly render PS biodegradable. This paper presents an investigation into the oxyfunctionalization of PS utilizing two iron based coordination complexes which catalyze the C–H activation and hydrogen peroxide oxidation of small molecule alkanes to ketones and alcohols. In principle, the chemistry applicable to small molecules should also be applicable to macromolecules, and the iron-based catalysts, [Fe(TPA)(MeCN)2][OTf]2 (I, TPA = tris(2-pyridylmethyl)amine) and [Fe(BPMEN)][OTf]2 (II, BPMEN = N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine) are used to induce oxyfunctionalization of PS by H2O2 to give polymeric products containing keto and hydroxyl groups. The polymeric products are characterized by IR and 1H NMR spectroscopy and by DSC and by GPC measurements.

Two non-heme iron(II) complexes, known to be effective catalysts for oxyfunctionalization of simple aliphatic molecules by hydrogen peroxide, are utilized to add keto and hydroxyl groups to atactic polystyrene.Figure optionsDownload as PowerPoint slide