Matches in DBpedia 2016-04 for { ?s ?p "In organic chemistry, the Cieplak effect is a predictive model that explains why nucleophiles preferentially add to one face of a carbonyl over another. Proposed by Andrzej Stanislaw Cieplak in 1980, it explains anomalous results that other models of the time, such as the Cram and Felkin-Anh models, can't justify. In the Cieplak model, electrons from a neighboring bond delocalize into the forming carbon-nucleophile (C-Nuc) bond, lowering the energy of the transition state and accelerating the rate of reaction. Whichever bond can best donate its electrons into the C-Nuc bond determines which face of the carbonyl the nucleophile will add to. The nucleophile may be a number of reagents, most commonly organometallic or reducing agents. The Cieplak effect is subtle, and often competes with sterics, solvent effects, counterion complexation of the carbonyl oxygen, and other effects to determine product distribution."@en }
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- Cieplak_Effect abstract "In organic chemistry, the Cieplak effect is a predictive model that explains why nucleophiles preferentially add to one face of a carbonyl over another. Proposed by Andrzej Stanislaw Cieplak in 1980, it explains anomalous results that other models of the time, such as the Cram and Felkin-Anh models, can't justify. In the Cieplak model, electrons from a neighboring bond delocalize into the forming carbon-nucleophile (C-Nuc) bond, lowering the energy of the transition state and accelerating the rate of reaction. Whichever bond can best donate its electrons into the C-Nuc bond determines which face of the carbonyl the nucleophile will add to. The nucleophile may be a number of reagents, most commonly organometallic or reducing agents. The Cieplak effect is subtle, and often competes with sterics, solvent effects, counterion complexation of the carbonyl oxygen, and other effects to determine product distribution.".