title: Polymerization of catechin catalyzed by Mn-, Fe- and Al-oxides.
abstract: The role of short-range order (SRO) metal oxides, which are common in acid soils and associated environments, in influencing the abiotic transformations of catechin, which is common in the soil of tea plantations, still remains poorly understood. The aim of this study was to investigate the catalytic power of SRO Mn(IV)-, Fe(III)- and Al-oxides in influencing the abiotic transformations of catechin. At the end of a 90-h reaction period, the release of CO(2) in all the oxide-catechin systems is higher than that for the system with only catechin. Polymerization of catechin is catalyzed and enhanced by SRO-oxides, as is indicated by the absorbance values of the supernatants, which were obtained via visible adsorption spectroscopy, and the yields of humic polymers. The sequence of the oxides that increased the yield of total humic polymers in these systems under ambient atmosphere is: Fe(III)-oxide>Mn(IV)-oxide>Al-oxide>>no catalyst (catechin). The electron spin resonance (ESR) and Fourier transformation infrared absorption spectrometry (FT-IR) of humic polymers formed in the oxide-catechin systems were similar to the spectra obtained from the humic polymers extracted from the soil. The catalytic power of SRO-oxides in promoting the oxidative polymerization of catechin, the resultant formation of humic substances, and C turnover in acid soils thus merit attention.
authors.affiliation: Department of Agricultural Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Yue Min
authors.initials: YM
authors.lastname: Chen
authors.forename: Tsung Ming
authors.initials: TM
authors.lastname: Tsao
authors.forename: Cheng Chung
authors.initials: CC
authors.lastname: Liu
authors.forename: Pan Ming
authors.initials: PM
authors.lastname: Huang
authors.forename: Ming Kuang
authors.initials: MK
authors.lastname: Wang
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D002392:Catechin / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D017895:Manganese Compounds / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D010087:Oxides / Q000737:chemistry*; D058105:Polymerization; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D005290:Ferric Compounds; D006812:Humic Substances; D017895:Manganese Compounds; D010087:Oxides; D012987:Soil; D002245:Carbon Dioxide; C000499:ferric oxide; C027424:manganese oxide; D002392:Catechin; D000537:Aluminum Oxide