Temperature Effects in the Enantiomeric Electro-Oxidation of <scp>d</scp>- and <scp>l</scp>-Glucose on Pt{643}^S

Abstract

The temperature dependence of the enantioselective adsorption of d- and l-glucose on a chiral Pt{643}S electrode is reported. The contribution to the electro-oxidation current of the initial adsorption of the glucose molecule on {111} terrace sites is used to determine a difference in the activation energy of adsorption between d- and l-glucose on Pt{643}S. A value of approximately 1.4 kJ mol-1 is obtained. When this value is converted into a diastereomeric product ratio, the mole percentage of the major product is evaluated as being 64%. Although small, it is speculated that optimization of the average terrace width of the chiral electrode surface will lead to an increase in the stereoselectivity of the reaction. These measurements constitute the first quantitative determination of enantiomeric selectivity at a metal electrode in the absence of a chiral promoter.