Polymer-Supported Transition Metal Catalysis(Ⅰ)-Oxidation of L-Ascorbic Acid by Using Chitosan-Cu(Ⅱ) and-Fe(Ⅲ) Complex Catalysts
Lee HK, Shin YJ
고분자에 지지된 천이금속촉매(Ⅰ) Chitosan-Cu(Ⅱ) 및-Fe(Ⅲ)착체 촉매에 의한 L-Ascorbic Acid의 산화
이학기, 신영조
Abstract
In the present study, Polymer supported metal complexes were synthesized by chelating chitosan with Cu(Ⅱ) and Fe(Ⅲ) ions and were investigated as catalysts for the oxidation of L-ascorbic acid The results obtained from this study can be summarized as follows: 1) The chitosan-Cu(Ⅱ) and -Fe(Ⅲ) complex catalysts exhibited relatively high catalytic effect and good catalyst recovery when compared to the cases of free Cu(Ⅱ) and Fe(Ⅲ) ions In tile oxidation of L-ascorbic acid and the kinetic behavior followed enzymatic kinetics of Michaelis-Menten type. 2) The chitosan-Cu(Ⅱ) complex catalytic showed higher catalytic activity than the chitosan-Fe(Ⅲ) system. 3) The catalytic reaction rate constants (kcat) of this oxidation at 25℃ were estimated to be 1.19 min-1 and 0.10 min-1 for the chitosan-Cu(Ⅱ) and -Fe(Ⅲ) catalyst systems, respectively. 4) The calculated parameters at 25℃ obtained with the Arrhenius and Eyring rate expressions for the chitosan-Cu(Ⅱ) and -Fe(Ⅲ) catalytic systems were as follows: Ea, 4.32 and 5.28 Kcal/mole; ΔG*, 7.34 and 18.81kca1/mo1c; ΔH*, 3.73 and 4.69 Kcal/mole; ΔS*, -0.046 and -0.047 cal/mole℃, respectively.
Polymer(Korea) 폴리머
Frequency : Bimonthly(odd) ISSN 0379-153X(Print) ISSN 2234-8077(Online) Abbr. Polym. Korea