ISSN:
1572-879X
Keywords:
enantioselective
;
hydrogenation
;
ketopantolactone
;
cinchonidine
;
catalyst pretreatment
;
adsorbate‐induced restructuring
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The influence of reductive and oxidative heat treatment on the enantioselectivity of chirally modified Pt/alumina has been reinvestigated, using the hydrogenation of ketopantolactone as a test reaction. Enhancement in ee by 39–49% has been observed after treatment in hydrogen at 250–600°C, as compared to untreated or preoxidized catalysts. The changes in ee after reductive and oxidative treatments are reversible, and always the final treatment is decisive. A HRTEM study indicates that adsorbate‐induced restructuring of Pt crystallites during hydrogen treatment at elevated temperature can play a role in the selectivity improvement, but the changes are superimposed by the strong structure‐directing effect of the alumina support. The possible contribution of other effects (complete reduction of Pt n+ surface species, removal of impurities, or change of Pt particle size) could be excluded.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1019085525317
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