Reactivity of syringyl quinone methide intermediates in dehydrogenative polymerization. Part 2: pH effect in horseradish peroxidase-catalyzed polymerization of sinapyl alcohol
-
Yuki Tobimatsu
Abstract
The solvent pH effect in the horseradish peroxidase (HRP)-catalyzed polymerization of sinapyl alcohol (S-alc) and analogously, sinapyl alcohol γ-O-glucoside (isosyringin, iso-S) was investigated particularly focusing on the behavior of syringyl-type quinone methide intermediates (S-type QMs) under acidic conditions. At first, the HRP-catalyzed polymerization of iso-S at pH 6.5–2.5, which produces water-soluble dehydrogenation polymer (DHP) intermediates in a homogeneous phase, was monitored by UV spectroscopy and gel permeation chromatography with photodiode array detection (GPC-PDA). Under acidic conditions at pH below 4.5, unstablilized S-type QMs from iso-S are rapidly quenched resulting in efficient productions of DHPs, although substantial loss of HRP activity and the resulting insufficient polymerization were inevitable at pH below 3.5. In addition, it was found that a small addition of guaiacyl-type comonomer (isoconiferin, iso-G) effectively promotes the polymerization of iso-S under acidic conditions, in which the comonomer serves as a radical mediator to facilitate the HRP-catalyzed oxidations of iso-S. Next, the HRP-catalyzed polymerization of S-alc at various pH values was conducted and the resulting DHPs were characterized by GPC and NMR measurements. The yields of isolated DHPs significantly increased as solvent pH decreased below 4.5. The structural analyses of the DHPs demonstrated that reaction selectivity of S-type QMs during the polymerization drastically changed at pH below 4.5: they react efficiently with water molecules as solvent leading to the formation of benzyl alcohol type β-O-4 substructures preferentially to the formation of α-O-aryl type substructures. Consequently, the data in this study demonstrated that acidic conditions at pH below 4.5 are favored in the dehydrogenative polymerization of S-alc from the viewpoint of the reactivity of S-type QMs.
©2010 by Walter de Gruyter Berlin New York
Articles in the same Issue
- Original Papers
- Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 1: Kraft pulp delignification
- Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 2: Application in TCF and ECF bleaching
- The role of hydroxyl and oxyl anion radicals in selectivity of oxygen delignification
- Thermal aging of 1-alkyl-3-methylimidazolium ionic liquids and its effect on dissolved cellulose
- Synchrotron X-ray fiber diffraction study on the thermal expansion behavior of cellulose crystals in tension wood of Japanese poplar in the low-temperature region
- Studies on the dehydrogenative polymerization of monolignol β-glycosides. Part 6: Monitoring of horseradish peroxidase-catalyzed polymerization of monolignol glycosides by GPC-PDA
- Reactivity of syringyl quinone methide intermediates in dehydrogenative polymerization. Part 2: pH effect in horseradish peroxidase-catalyzed polymerization of sinapyl alcohol
- Fractionation, analysis, and PCA modeling of properties of four technical lignins for prediction of their application potential in binders
- New model for predicting tensile strength and density of eucalyptus handsheets based on an activation parameter calculated from fiber distribution characteristics
- Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents
- Surface properties of extracts from cork black condensate
- Effect of helium DBD plasma treatment on the surface of wood samples
- Preparation of thermoplastic molding from steamed Japanese beech flour
- Alteration of the unsteady sorption behaviour of maple (Acer pseudoplatanus L.) and spruce (Picea abies (L.) Karst.) due to thermal modification
- Towards improved understanding of PEG-impregnated waterlogged archaeological wood: A model study on recent oak
- Determination of the change in appearance of lumber surfaces illuminated from various directions
- A study of water exchange in wood by means of 2D NMR relaxation correlation and exchange
- Measurement of surface growth stress in Eucalyptus nitens Maiden by splitting a log along its axis
- Obituary
- Dion Chen-Loung Chen (1930–2009)
- Meetings
- Meetings
Articles in the same Issue
- Original Papers
- Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 1: Kraft pulp delignification
- Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 2: Application in TCF and ECF bleaching
- The role of hydroxyl and oxyl anion radicals in selectivity of oxygen delignification
- Thermal aging of 1-alkyl-3-methylimidazolium ionic liquids and its effect on dissolved cellulose
- Synchrotron X-ray fiber diffraction study on the thermal expansion behavior of cellulose crystals in tension wood of Japanese poplar in the low-temperature region
- Studies on the dehydrogenative polymerization of monolignol β-glycosides. Part 6: Monitoring of horseradish peroxidase-catalyzed polymerization of monolignol glycosides by GPC-PDA
- Reactivity of syringyl quinone methide intermediates in dehydrogenative polymerization. Part 2: pH effect in horseradish peroxidase-catalyzed polymerization of sinapyl alcohol
- Fractionation, analysis, and PCA modeling of properties of four technical lignins for prediction of their application potential in binders
- New model for predicting tensile strength and density of eucalyptus handsheets based on an activation parameter calculated from fiber distribution characteristics
- Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents
- Surface properties of extracts from cork black condensate
- Effect of helium DBD plasma treatment on the surface of wood samples
- Preparation of thermoplastic molding from steamed Japanese beech flour
- Alteration of the unsteady sorption behaviour of maple (Acer pseudoplatanus L.) and spruce (Picea abies (L.) Karst.) due to thermal modification
- Towards improved understanding of PEG-impregnated waterlogged archaeological wood: A model study on recent oak
- Determination of the change in appearance of lumber surfaces illuminated from various directions
- A study of water exchange in wood by means of 2D NMR relaxation correlation and exchange
- Measurement of surface growth stress in Eucalyptus nitens Maiden by splitting a log along its axis
- Obituary
- Dion Chen-Loung Chen (1930–2009)
- Meetings
- Meetings
