ISSN:
1572-879X
Keywords:
Pt/Al2O3
;
promotion by tin
;
modification by tin tetraalkyls
;
surface organometallic complexes
;
enantioselective hydrogenation
;
ethyl pyruvate
;
dihydrocinchonidine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The enantioselective hydrogenation of ethyl pyruvate has been studied on a Pt/Al2O3-dihydrocinchonidine catalyst promoted with different amount of tin. The surface reaction between hydrogen adsorbed on Pt and tin tetraalkyls is used for the tin introduction. This reaction leads to the formation of surface organometallic complexes (I), with SnR(4-x) moieties anchored to the platinum surface. The enantioselectivity of the Pt/Al2O3-dihydrocinchonidine catalyst is found to change only slightly upon promotion with tin, while the rate of ethyl pyruvate hydrogenation depends strongly on the amount and the form of tin introduced. The hydrogenation activity is suppressed completely at relatively low tin coverage (Sn/Pts 〈 0.06). The highest hydrogenation rate is measured over catalysts containing complex (I) (Sn/Pts = 0.025) on the platinum surface. On Sn-Pt alloy type active sites, which are formed after decomposition of (I) in hydrogen, the rate of hydrogŋation is considerably lower than on the unpromoted reference Pt/Al2O3 catalyst.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00769167
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