KMID : 1059519960400040254
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Journal of the Korean Chemical Society 1996 Volume.40 No. 4 p.254 ~ p.263
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Catalytic Effects of Co(¥²) Complexes on the Hydrolysis of p-Nitrophenyl Picolinate
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Noh Jae-Geun
Kim Chang-Suk Hong Soon-Yung
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Abstract
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Five cobalt(¥²) complexes were synthesized from bi- or tridentate nitrogen ligands. Catalytic actions of these complexes for hydrolyses of p-nitrophenyl picolinate, p-nitrophenyl nicotinate, and p-nitrophenyl isonicotinate were investigated by a spectrophotometric method. p-Nitrophenyl picolinate showed the most senstive reaction among three substrates by these catalysts. Aquohydroxo Co(¥²) complexes raised as much as 21¡40 times the rate of hydrolysis of p-nitrophenyl picolinate at pH 6.5. Activities of complexes were in the order: Co(ibpn)(OH)2(OH2) > Co(aepn)(OH)2(OH2) > Co(tn)2(OH)(OH2) > Co (bpy)2(OH)(OH2) > Co(dien)(OH)2(OH2). Catalytic hydrolysis was postulated to proceed through a intramolecular general base catalysis path which is mixed by a partial intramolecular nucleophilic catalysis.
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