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Gas-phase dehydration of vicinal diols to epoxides: Dehydrative epoxidation over a Cs/SiO2 catalyst.
- Source :
-
Journal of Catalysis . Mar2015, Vol. 323, p85-99. 15p. - Publication Year :
- 2015
-
Abstract
- A novel type of dehydration reaction that produces epoxides from vicinal diols (dehydrative epoxidation) using a basic catalyst is reported. Epoxyethane, 1,2-epoxypropane, and 2,3-epoxybutane were produced from the dehydrative epoxidation of ethylene glycol, 1,2-propanediol, and 2,3-butanediol, respectively. Among a number of tested basic catalysts, the Cs/SiO 2 catalyst showed outstanding performance for the dehydrative epoxidation of 2,3-butanediol and is considered to be the most promising catalyst for this type of reaction. In order to identify the superiority of the Cs/SiO 2 catalyst and a mechanism of the reaction, structure–activity relationships were studied along with density functional theory (DFT) calculations. The following features are found to be responsible for the excellent activity of the Cs/SiO 2 catalyst: i) strong basic sites formed by Cs + , ii) low penetration of Cs + into SiO 2 which permits basic sites to be accessible to the reactant, iii) stable basic sites due to the strong interactions between Cs + and SiO 2 surface, and iv) mildly acidic surface of SiO 2 which is advantageous for the elimination to H 2 O. In addition, the dehydrative epoxidation involves an inversion of chirality (e.g. meso -2,3-butanediol ( R,S ) to trans -2,3-epoxybutane ( R,R or S,S )), which is in agreement with DFT results that the reaction follows a stereospecific S N 2-like mechanism. [ABSTRACT FROM AUTHOR]
- Subjects :
- *DEHYDRATION reactions
*EPOXY compounds
*EPOXIDATION
*SILICA
*METAL catalysts
Subjects
Details
- Language :
- English
- ISSN :
- 00219517
- Volume :
- 323
- Database :
- Academic Search Index
- Journal :
- Journal of Catalysis
- Publication Type :
- Academic Journal
- Accession number :
- 100981917
- Full Text :
- https://doi.org/10.1016/j.jcat.2014.12.023