J. Byun, Y. Park, C. Han
1999
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Journal
Journal of The Korean Chemical Society
Abstract
Direct preparative method of 2,6-diformyl-p-cresol and 2-hydroxy-3-hydroxy-5-methylbenzaldehyde from 2,6-bis(hydroxymethyl)-4-methylphenol using activated was described. Hexadentate compartmental Iigands, were prepared by condensation reactions of 2-hydroxy-3-hydroxy methyl-5-methylbenzaldehyde with ethylenediamine and 1,3-diaminopropane respectively. By the reaction of macrocycle() with Ln(III) nitrate {Ln(III)=Pr, Sm, Cd, Dy }, discrete mononuclear Ln(III) complexes of the type were synthesized in the solid state. was placed in methanol for 2 days, and was formed. The equilibrium constants(K) for the substitution of coordinated in the Ln-[20]DOTA complexes by various auxiliary ligand, (=salicylic acid, p-chlorobenzoic acid, benzoic acid, acetic acid, 4-bromophenol) were determined spectroscopically at 25 and 0.1M . The K values calculated were in the order of salicylic acid > p-chlorobenzoic acid > benzoic acid > acetic acid > 4-bromophenol, while pKa of auxiliary ligands was in the opposite trend.