Increasing global demand for fossil resources has sparked a renewed interest in catalytic technologies for the conversion of hydrocarbons from petroleum and natural gas to higher value chemicals. For example, styrene is produced from benzene and ethylene on a scale of approximately 18.5 million tons annually. The current route for styrene production involves acid-catalyzed formation of ethylbenzene, trans-alkylation to optimize the yield of mono-functionalized product, and dehydrogenation of ethylbenzene. The direct oxidative conversion of benzene and ethylene to styrene has been realized using the catalyst (FlDAB)Rh(X)(η2–C2H4) [FlDAB = N,N'-bis(pentafluorophenyl-2,3-dimethyl-1,4-diaza-1,3-butadiene; X = acetate or trifluoroacetate] and air-recyclable Cu(II) oxidants to produce styrene with yields ≥ 95% (based on Cu(II) as the limiting reagent) and high selectivity. Given that almost all other catalysts that have been reported for this oxidative arene vinylation suffer from low selectivity, we sought to probe the mechanism. A combined experimental and computational study revealed that the rhodium–carboxylate moiety plays a key role in the rate of catalysis. Given this insight, we have studied the mechanism of oxidative arene vinylation catalysis using other group 9 and 10 complexes to determine if the effect of the carboxylate is conserved.

Mechanistic studies of oxidative arene vinylation catalyzed by late transition metals

253rd National Meeting (2017)

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