Quantum Chemical Modeling of Propene and Butene Epoxidation with Hydrogen Peroxide
Artikel i vetenskaplig tidskrift, 2008

The mechanism of hydrogen peroxide assisted epoxidation of propene, 1-butene, trans-2-butene, cis-2-butene, and isobutene was studied using density functional theory calculations. The results are rationalized in the context of the previously proposed direct pathway for epoxidation of ethene with hydrogen peroxide and compared to the indirect pathway involving Ti(IV) peroxide groups. The indirect Ti(IV) peroxide pathway displays a 57.8 kJ mol-1 activation enthalpy for the rate limiting step [Phys. Chem. Chem. Phys. 2007, 9, 5997]. In contrast, a lowering of the activation enthalpy is observed for the direct mechanism according to 72.3 (ethene), 53.9 (1-butene), 53.5 (propene), 46.9 (trans-2-butene), 46.6 (isobutene), and 42.6 (cis-2-butene) kJ mol-1 when the reaction takes place on a binuclear Ti(IV) dihydroxide site. These values clearly show that the direct pathway becomes the most favorable. The stability of the epoxides toward hydrolysis to the corresponding diols are also addressed. The present work clearly demonstrates the generality and efficiency of a binuclear dihydroxide site in catalyzing the epoxidation of olefins with hydrogen peroxide, thus avoiding the formation of a surface peroxide group.

Författare

Angelica Lundin

Göteborgs universitet

Itai Panas

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Elisabet Ahlberg

Göteborgs universitet

Journal of Physical Chemistry A

1089-5639 (ISSN) 1520-5215 (eISSN)

Vol. 113 282-290

Ämneskategorier

Teoretisk kemi

Kemi

DOI

10.1021/jp805720r