Brushing Away Toxicity

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Science  10 May 2013:
Vol. 340, Issue 6133, pp. 661-662
DOI: 10.1126/science.340.6133.661-d

Osmium tetroxide is among the most useful and versatile oxidizing agents of olefins, accounting for its widespread application in chemistry research despite its dangerous combination of toxicity and volatility. Basavaraju et al. have constructed a microfluidic reactor that safely confines the compound without unduly compromising its reaction kinetics. The design incorporates high-surface-area nanobrush polymers that tether the osmium (Os) to the reactor while leaving it readily accessible to the incoming reagents. Coating conventional polydimethylsiloxane with a polyvinylsilazane layer before grafting these brushes rendered the interior of the reactor tolerant to organic solvents. Addition of tetrahydrofuran stabilized the catalytic quantities of the bound Os complex in the +6 oxidation state, after which olefins could be readily dihydroxylated or oxidatively cleaved through reaction with stoichiometric N-methylmorpholine-N-oxide or periodate, respectively. The system could be reused after 3 months with no degradation in performance.

Angew. Chem. Int. Ed. 52, 10.1002/anie.201301124 (2013).

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