The chemoselective hydrogenation of a,�-unsaturated aldehydes to corresponding saturated aldehydes or unsaturated alcohols is industrially important route to produce valuable starting materials for chemical synthesis. Especially unsaturated alcohols are important intermediates in pharmaceutical and fragrance industries. However, the chemoselective hydrogenation to desired unsaturated alcohols is difficult to achieve as the hydrogenation of the C=C bond is thermodynamically (35 kJ/mol) preferred over C=O bond. Previous DFT calculations suggested that the reaction favors the hydrogenation of the C=O bond and the chemoselectivity is determined by the desorption energy difference between the two products.Herein, we present the new DFT calculations which favor the hydrogenation of the experimentally observed C=C bond selectivity. The results also correlate well with other experimental results and DFT-studies on a silver surface. The contrary chemoselectivity to previously published computationalresults arise from the fact that the lowest transition state to hydrogenate C=C bond is through the p-bonded intermediate not the di-s-bonded. Similar behavior of the C=C bond on platinum and palladium surfaces is well known with the unconjugated alkenes. We have also observed that the surface coverage has a major role on the relations between different activation barriers, and  the obtained  results present excellent BEP  correlations

Selective hydrogenation of a,�-unsaturated aldehydes acrolein and prenal on platinium and palladium surfaces from DFT calculations

247th National Meeting (2014)

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