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KMID : 1059519960400060445
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Journal of the Korean Chemical Society
1996 Volume.40 No. 6 p.445 ~ p.452
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Catalytic Hydrogenation of Unsaturated Organic Compounds by Rutheniumhydridonitrosyl Complexes
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Park Mi-Young
Kim Young-Joong
Cho Ook-Jae
Lee Ik-Mo
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Abstract
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Catalytic hydrogenation of ketones and aldehydes by RuH(NO)L3 (L3: PPh3, PhP(CH2CH2PPh2)2(etp)) was investigated to examine the reaction mechanism and the competence of hydridonitrosyl complexes as catalysts for organic synthesis. RuH(NO)L3 showed catalytic activity for the hydrogenation and the activities of catalysts were dependent on the steric and electronic factors. The less the steric demands of the substrates become, the more activity the catalysts show. For the electronic effect, the more the partial positive charge on the carbonyl carbon atom in ketones becomes and the more the double bond character of carbonyl group in aldehydes becomes, the more active the catalysts are. These results reflect the difference of reaction mechanisms of two substrates, ketones and aldehydes. Catalytic activities of RuH(NO)(etp) and RuH(NO)(PPh3)3 in the presence of extra PPh3 toward hydrogenation showed the existence of a reaction pathway accompanied with the change of the bonding modes of NO ligand. The roles of excess PPh3 change with increase of the mole ratio of PPh3 to catalysts; prevention of ligand dissociation from comlexes → bases → ligands. The activity of RuH(NO)(etp) was lower than that of RuH(NO)(PPh3)3 toward the hydrogenation of the same substrates mainly due to the structural difference. These catalysts showed the selectivity toward olefin hydrogenation over carbonyl groups in the competitive reaction.
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KEYWORD
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