title: An operando FTIR spectroscopic and kinetic study of carbon monoxide pressure influence on rhodium-catalyzed olefin hydroformylation.
abstract: The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83 MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2 MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30 °C and low pressure of p(CO)=0.2 MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete.
authors: Leibniz-Institut für Katalyse e.V. Universität Rostock, Albert-Einstein-Str. 29a, 18059 Rostock (Germany), Fax: (+49) 381-128151169.
authors: Christoph
authors: C
authors: Kubis
authors: Mathias
authors: M
authors: Sawall
authors: Axel
authors: A
authors: Block
authors: Klaus
authors: K
authors: Neymeyr
authors: Ralf
authors: R
authors: Ludwig
authors: Armin
authors: A
authors: Börner
authors: Detlef
authors: D
authors: Selent
keywords: IR spectroscopy; hydroformylation; kinetics; operando; rhodium