"Mechanistic studies of single-step styrene production using a rhodium(!) catalyst"

Document Type

Article

Publication Date

2017

Abstract

Styrene is produced on a scale of ∼18.5 million tons annually for use in plastics, elastomers, and fine chemicals.(1-5) Industrial synthesis of styrene often involves an acid-catalyzed (i.e., Friedel–Crafts or zeolite catalysis) arene alkylation to form ethylbenzene, trans-alkylation to optimize yield, and ethylbenzene dehydrogenation.(1-10) Although this method has been employed by industry for many years, there are some disadvantages.(2) Dehydrogenative addition of an arene C–H bond across an olefin C═C bond (i.e., oxidative arene vinylation) provides a potential route to directly synthesize vinyl arenes from arenes, olefins, and oxidants. For styrene production, one possible route involves metal-mediated activation of the C–H bond of benzene to yield a M–Ph bond, ethylene insertion into the resulting M–Ph bond to produce a M-CH2CH2Ph complex, and β-hydride elimination from the resulting M-CH2CH2Ph complex to give coordinated styrene and a M–H bond (Scheme 1). Subsequent styrene dissociation (regardless of mechanism) and reaction with oxidant can regenerate the active catalyst, and if the oxidant is oxygen (either used in situ or used to recycle an in situ oxidant), the net reaction is the thermodynamically favorable conversion of benzene, ethylene, and oxygen to styrene and water (eq 1).(11)

DOI

10.1021/jacs.6b10658

Comments

Vaughan, B. A.; Khani, S. K.; Gary, J . B.; Kammert, J. D.; Webster-Gardiner; M. S.; McKeown, B. A.; Davis, R. J.; Cundari, T. R.; Gunnoe, T. B. "Mechanistic studies of single-step styrene production using a rhodium(!) catalyst" J. Am. Chem. Soc. 2017, 139, 1485-1498.

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