Polyoxometalate oxidation of non-phenolic lignin subunits in water: Effect of substrate structure on reaction kinetics
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| 024 | 7 | 0 | |a 10.1515/HF.2004.016 |2 doi |
| 035 | |a (NATIONALLICENCE)gruyter-10.1515/HF.2004.016 | ||
| 245 | 0 | 0 | |a Polyoxometalate oxidation of non-phenolic lignin subunits in water: Effect of substrate structure on reaction kinetics |h [Elektronische Daten] |c [T. Yokoyama, H.-M. Chang, R. S. Reiner, R. H. Atalla, I. A. Weinstock, J. F. Kadla] |
| 520 | 3 | |a The effect of lignin-biopolymer structure on the mechanism of its oxidative depolymerization by polyoxometalates (POMs) was investigated by reacting an equilibrated POM ensemble with a series of ring-substituted benzyl alcohols. Under anaerobic conditions in mixed water/methanol, observed pseudo-first order reaction rates (150°C) of 8.96 × 10−3 and 4.89 × 10−3 sec−1 were obtained for oxidations of 1-(3,4-dimethoxyphenyl) ethanol (1) and 1-(3,4,5-trimethoxyphenyl)ethanol (2), respectively. Organic products from the oxidation of 2 (95% recovery) indicate the reaction proceeds via successive oxidations of the benzylic carbon atom; aromatic-ring cleavage was not observed. A primary kinetic-isotope effect of 1.6 and 1.7 was observed for the reactions of 1 and 2 deuterated at the benzylic-carbon atoms. This combined with the relatively large activation energies, indicate that C-H bond breaking (either H-atom or proton-coupled electron transfer) occurs late along the reaction coordinate of the rate-determining step. Replacing the 4-CH3O-group in 2 by CH3CH2O- to give 1-(4-ethoxy-3,5-dimethoxyphenyl)ethanol (3), had a substantial effect on the temperature dependence of the observed reaction rate, suggestive of a possible change in mechanism. | |
| 540 | |a Copyright © 2004 by Walter de Gruyter GmbH & Co. KG | ||
| 690 | 7 | |a Timber & wood processing |2 nationallicence | |
| 690 | 7 | |a Biotechnology |2 nationallicence | |
| 690 | 7 | |a Materials science |2 nationallicence | |
| 700 | 1 | |a Yokoyama |D T. |4 aut | |
| 700 | 1 | |a Chang |D H.-M |4 aut | |
| 700 | 1 | |a Reiner |D R. S. |4 aut | |
| 700 | 1 | |a Atalla |D R. H. |4 aut | |
| 700 | 1 | |a Weinstock |D I. A. |4 aut | |
| 700 | 1 | |a Kadla |D J. F. |4 aut | |
| 773 | 0 | |t Holzforschung |d Walter de Gruyter |g 58/2(2004-03-15), 116-121 |x 0018-3830 |q 58:2<116 |1 2004 |2 58 |o hfsg | |
| 856 | 4 | 0 | |u https://doi.org/10.1515/HF.2004.016 |q text/html |z Onlinezugriff via DOI |
| 908 | |D 1 |a research article |2 jats | ||
| 950 | |B NATIONALLICENCE |P 856 |E 40 |u https://doi.org/10.1515/HF.2004.016 |q text/html |z Onlinezugriff via DOI | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Yokoyama |D T. |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Chang |D H.-M |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Reiner |D R. S. |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Atalla |D R. H. |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Weinstock |D I. A. |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Kadla |D J. F. |4 aut | ||
| 950 | |B NATIONALLICENCE |P 773 |E 0- |t Holzforschung |d Walter de Gruyter |g 58/2(2004-03-15), 116-121 |x 0018-3830 |q 58:2<116 |1 2004 |2 58 |o hfsg | ||
| 900 | 7 | |b CC0 |u http://creativecommons.org/publicdomain/zero/1.0 |2 nationallicence | |
| 898 | |a BK010053 |b XK010053 |c XK010000 | ||
| 949 | |B NATIONALLICENCE |F NATIONALLICENCE |b NL-gruyter | ||