@article{wan_lu_xiao_du_miyakoshi_chen_knill_kennedy_2010, title={Effects of organic solvents on the activity of free and immobilised laccase from Rhus vernicifera}, volume={47}, number={4}, journal={International Journal of Biological Macromolecules}, author={Wan, Y. Y. and Lu, R. and Xiao, L. and Du, Y. M. and Miyakoshi, T. and Chen, C. L. and Knill, C. J. and Kennedy, J. F.}, year={2010}, pages={488–495} }
 @article{harigaya_honda_rong_miyakoshi_chen_2007, title={Enzymatic dehydrogenative polymerization of urushiols in fresh exudates from the lacquer tree, Rhus vernicifera DC}, volume={55}, ISSN={["0021-8561"]}, DOI={10.1021/jf063161g}, abstractNote={Fresh exudates from the lacquer tree, Rhus vernicifera DC, were extracted with acetone and the solution was chromatographed to isolate monomer, dimer, trimer, and oligomer fractions of urushiols. Constituents of the monomeric and dimeric fractions were then identified by two-dimensional (2D) 1H-13C heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond coherence (HMBC) NMR spectroscopic techniques. The results showed that the monomeric fraction contained 3-[8'Z,11'E,13'Z-pentadecatrienyl]catechol (1), 3-[8'Z,11'Z,14'-pentadecatrienyl]catechol (2), and 3-pentadecanyl]catechol (3), which was verified by HPLC analysis. The dimeric fraction contained 8'-(3' ',4' '-dihydroxy-5' '-alkenyl)phenyl-3-[9'E,11'E,13'Z-pentadecatrienyl]catechol (4), 14'-(3' ',4' '-dihydroxy-5' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadecatrienyl]catechol (5), 2-hydroxyl-3- or -6-alkenylphenyl ethyl ether (6), 14'-(3' ',4' '-dihydroxy-2' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadeca-trienyl]catechol (7), 15'-(2' '-hydroxy-3' '- or -6' '-alkenyl)phenyloxy-3-[8'Z,11'Z,13'E)-pentadecatrienyl]catechol (8), 14'-(2' ',3' '-dihydroxy-4' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadecantrienyl]catechol (9), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-4,3'-biphenyl (10), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-4,4'-biphenyl (11), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-5,4'-biphenyl (12), and 1,2,1'-trihydroxy-6,6'-dialkenyldibenzofuran (13) as constituents. In addition, dimeric ethers and peroxides, such as compounds 14 and 15, were produced by autoxidation of monomeric urushiols in atmospheric air. The possible reaction mechanisms for the dehydrogenative polymerization of urushiols by Rhus laccase present in the fresh raw exudates under the atmospheric oxygen are discussed on the basis of structures identified. This is of primary importance because the use of the urushi exudates as coating materials does not involve organic solvents and is an environmentally friendly process.}, number={6}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Harigaya, Sayoko and Honda, Takayuki and Rong, Lu and Miyakoshi, Tetsuo and Chen, Chen-Loung}, year={2007}, month={Mar}, pages={2201–2208} }
 @article{sousa_silva_miyakoshi_chen_2006, title={Constituents of the root wood of Austroplenckia populnea var. ovata}, volume={69}, ISSN={["1520-6025"]}, DOI={10.1021/np068004q}, abstractNote={The root wood of Austroplenckia populnea var. ovata was extracted successively with chloroform and methanol. Lapachol and dehydro-beta-lapachone were isolated from the chloroform extract, and euonine, alatusinine, wilfordine, 2-O-deacetyleuonine (1), 7-O-deacetyleuonine (2), and austronine (3) from the methanol extract. The structures of the new compounds 1-3 were elucidated by spectroscopic data interpretation. Lapachol, dehydro-beta-lapachone, euonine, alatusinine, and wilfordine are known compounds that are newly identified from root wood of Austroplenckia populnea.}, number={8}, journal={JOURNAL OF NATURAL PRODUCTS}, author={Sousa, Jose R. and Silva, Gracia D. F. and Miyakoshi, Tetsuo and Chen, Chen-Loung}, year={2006}, month={Aug}, pages={1225–1227} }
 @article{capanema_balakshin_chen_gratzl_2006, title={Oxidative ammonolysis of technical lignins. Part 4. Effects of the ammonium hydroxide concentration and pH}, volume={26}, ISSN={["0277-3813"]}, DOI={10.1080/02773810600582350}, abstractNote={Abstract The effects of ammonium hydroxide concentration and pH on the kinetics and reaction mechanism of oxidative ammonolysis of Repap organosolv lignin were studied. The reactions were carried out at 100°C with an oxygen pressure of 8 bar (116 psi) and 0.4–1.6 M [NH4OH] and 9–12.7 pH. The resulting N‐modified lignins were analyzed for elemental composition and methoxyl group content. An increase in ammonium hydroxide concentration increased the rate of nitrogen incorporation, oxygen consumption, CO2 formation, and lignin dissolution. The rate of nitrogen incorporation was 0.5 order with respect to NH4OH concentration. The amount of oxygen consumed, oxygen incorporated into the lignin, CO2 formed, and OMe groups eliminated per mole of nitrogen incorporated decreased with increasing ammonium hydroxide concentration indicating that the increase in [NH4OH] accelerated nitrogen incorporation more than lignin oxidation. The dependence of the rate of nitrogen incorporation on the reaction pH went through a maximum leading to the conclusion that HO− competes with ammonia in reactions with electrophilic lignin centers resulting in interruption of nitrogen incorporation into the lignin.}, number={1}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={Capanema, EA and Balakshin, MY and Chen, CL and Gratzl, JS}, year={2006}, pages={95–109} }
 @article{wang_chen_gratzl_2005, title={Dechlorination of chlorophenols found in pulp bleach plant E-1 effluents by advanced oxidation processes}, volume={96}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2004.08.011}, abstractNote={Studies were conducted on the response of 2,4,6-trichlorophenol (1), 2,3,4,5-tetrachloro-phenol (2) and 4,5-dichloroguaiacol (3) toward advanced oxidation processes, such as UV-, O2/UV-, H2O2/UV-, O3/UV- and O3-H2O2/UV-photolyses with irradiation of 254 nm photons. The compounds 1-3 are among the chlorophenols found in the Kraft-pulp bleach plant E-1 effluents. The studies were extended to treatment of these compounds with ozonation and O3-H2O2 oxidation systems in alkaline aqueous solution. Except for the O2/UV-photolysis of 1 and H2O2/UV-photolysis of 2, the dechlorination of 1-3 by O2/UV- and H2O2/UV-potolyses were less effective than the corresponding N2UV-potolysis of 1-3. Guaiacol-type chlorophenols were more readily able to undergo dechlorination than non-guaiacol type chlorophenols by N2/UV-, O2/UV- and H2O2/UV-potolyses. In addition, the efficiency for the dechlorination of 1-3 by N2/UV-, O2/UV- and H2O2/UV-potolyses appeared to be dependent upon the inductive and resonance effects of substituents as well as number and position of chlorine substituent in the aromatic ring of the compounds. The dechlorination of 2 by treatment with O3 alone is slightly more effective than the corresponding the O3/UV-photlysis, whereas the dechlorination of 2 by treatment with the combination of O3 and H2O2 was slightly less effective than the corresponding O3-H2O2/UV-photolysis. In contrast, the dechlorination of 3 on treatment with O3 alone was slightly less effective than the corresponding the O3/UV-photolysis, whereas the dechlorination of 3 on treatment with the combination of O3 and H2O2 was slightly more effective than the corresponding the O3-H2O2/UV-photolysis. In the dechlorination of 2 and 3, chemical species derived from ozone and hydrogen peroxide in alkaline solution were dominant reactions in the O3/UV- and O3-H2O2/UV-photolysis systems as in the O3 and O3-H2O2 oxidation systems. Possible dechlorination mechanisms involved were discussed on the basis of kinetic data.}, number={8}, journal={BIORESOURCE TECHNOLOGY}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2005}, month={May}, pages={897–906} }
 @article{xie_chen_gratzl_2005, title={Dechlorination of pulp bleaching plant E-1 effluent by ArF* and KrF* excirner laser photolysis. Part 1. Dechlorination of chlorophenols identified in E-1 effluent}, volume={172}, ISSN={["1010-6030"]}, DOI={10.1016/j.jphotochem.2004.10.021}, abstractNote={Among the chlorophenols identified in the bleaching plant E-1 effluent, 4,5-chloroguaiacol (2), 3,4,5,6-tetrachloroguaiacol (3), 2,4,6-trichlorophenol (4) and 2,3,4,5-chlorophenol (5) were selected as model compounds for dechlorination at pH 7 and 10.5 in nitrogen- and oxygen-saturated aqueous solutions at 20 °C by ArF* (193 nm) and KrF* (248 nm) excimer laser photolyses. The ArF* (193 nm) excimer laser photolysis was more effective than the KrF* (248 nm) excimer laser photolysis in dechlorinating 2–5. The dechlorinations of 2–5 were determined to be first order reactions; first order with respect to total organically bound chlorine of substrate, first order overall. The efficiency of dechlorination was found to depend on the initial pH of reaction mixture, substituent pattern of 2–5, and the wavelength of excimer laser radiation. The dechlorination rates of chlorinated guaiacols 2 and 3 were faster than the chlorinated phenols 4 and 5 under the same reaction condition while rate of 3 was faster than that of 2. Furthermore, the dechlorination rate of a substrate increased with increasing initial pH. The dechlorination rates of chlorophenols investigated were almost the same in N2- and O2-saturated solutions. However, when 2% H2O2 per substrate was added to the initial reaction mixture of 5 in the ArF* (193 nm) excimer laser photolysis, the dechlorination rate increased considerably. Quantum yields (Φ) for the generation of chloride ions were determined for the ArF* (193 nm) and KrF* (248 nm) excimer laser photolyses of 2–5 in both N2- and O2-saturated solutions. In general, the quantum yields in O2-saturated solutions were slightly higher than the corresponding values in N2-saturated solutions and was increased appreciably with addition of 2% H2O2.}, number={3}, journal={JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY}, author={Xie, TY and Chen, CL and Gratzl, JS}, year={2005}, month={Jun}, pages={222–230} }
 @article{xie_chen_gratzl_2005, title={Dechlorination of pulp bleaching plant E-1 effluent by ArF* and KrF* excirner laser photolysis. Part 2. Dechlorination of polychlorinated oxylignins}, volume={172}, ISSN={["1010-6030"]}, DOI={10.1016/j.jphotochem.2004.11.018}, abstractNote={Abstract The E-1 effluent from bleaching of pine kraft pulp was fractionated by ultrafiltration to obtain polychlorinated oxylignin fractions, PCOL-1, PCOL-2, PCOL-3 and POCL-4 with relative molecular mass ( M r ) of 6500, 6000, 5500 and 3500, respectively. These PCOLs were characterized by elemental and functional group analyses, and gel permeation chromatography. The PCOLs were decolorized and dechlorinated in the presence of H 2 O 2 in O 2 -saturated solution at 20 °C by ArF * (193 nm) excimer photolysis. The results showed that both the decolorization and dechlorination were dependent on both the initial pH and concentration of H 2 O 2 per substrate in the reaction mixture. In general, the decolorization increases with increasing pH and concentration of added H 2 O 2 . At pH 10.5 with 8% H 2 O 2 per substrate to the initial reaction mixture, approximately 70% of chromophoric structures were degraded within the initial 60 min irradiation of ArF * (193 nm) laser radiation, then leveled off. The dechlorination reactions followed first order reaction law; first order with respect to total organically bound chlorine; first order overall. The dechlorination rates increase with increasing both pH and concentration of H 2 O 2 per substrate. The quantum yields ( Φ ) for the generation of chloride ions from PCOLs in the presence of 2% H 2 O 2 were appreciably lower than the values observed for the monomeric chlorophenols, in the range of approximately 0.03 versus 0.9. The ArF * excimer laser photolysis of PCOLs were also monitored by gel permeation chromatography. PCOL-2 was degraded into fragments with relative molecular mass ( M r ) of approximately 1500. Similarly, PCOL-3 and PCOL-4 were degraded into fragments with M r of approximately 4000 and 3000, respectively. In contrast, the M r of PCOL-1 was increased to approximately 6500, indicating the occurrence of condensation among the degraded fragments.}, number={3}, journal={JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY}, author={Xie, TY and Chen, CL and Gratzl, JS}, year={2005}, month={Jun}, pages={231–240} }
 @article{capanema_balakshin_chen_2004, title={An improved procedure for isolation of residual lignins from hardwood kraft pulps}, volume={58}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2004.070}, abstractNote={Abstract}, number={5}, journal={HOLZFORSCHUNG}, author={Capanema, EA and Balakshin, MY and Chen, CL}, year={2004}, pages={464–472} }
 @article{wang_chen_gratzl_2004, title={Dechlorination and decolorization of chloro-organics, in pulp bleach plant E-1 effluents, by advanced oxidation processes}, volume={94}, DOI={10.1016/j.biotech.2004.01.005}, number={3}, journal={Bioresource Technology}, author={Wang, R. and Chen, C. L. and Gratzl, J. S.}, year={2004}, pages={267–274} }
 @article{wang_chen_gratzl_2004, title={Ozonation of pine kraft lignin in alkaline solution. Part 1: Ozonation, characterization of kraft lignin and its ozonated preparations}, volume={58}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2004.116}, abstractNote={Abstract}, number={6}, journal={HOLZFORSCHUNG}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2004}, pages={622–630} }
 @article{wang_chen_gratzl_2004, title={Ozonation of pine kraft lignin in alkaline solution. Part 2: Surface active properties of the ozonated kraft lignins}, volume={58}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2004.117}, abstractNote={Abstract}, number={6}, journal={HOLZFORSCHUNG}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2004}, pages={631–639} }
 @article{alves_capanema_chen_gratzl_2003, title={Comparative studies on oxidation of lignin model compounds with hydrogen peroxide using Mn(IV)-Me(3)TACN and Mn(IV)-Me4DTNE as catalyst}, volume={206}, ISSN={["1381-1169"]}, DOI={10.1016/S1381-1169(03)00448-5}, abstractNote={Comparative studies are conducted on the kinetics and reaction mechanism for the oxidation of lignin model compounds, 1-(3,4-dimethoxyphenyl)ethanol (1), 1-(3,4-dimethoxyphenyl)-1-propene (2) and E-1,2-diphenylethene (3) with hydrogen peroxide at reaction temperatures below 80 °C using [LMn(IV)(μ-O)3Mn(IV)L](PF6)2 (C-1) and [L′Mn(IV)(μ-O)3Mn(IV)](ClO4)2 (C-2) as catalyst. The disappearance rate of 1 and 2 in the first phase of C-1-catalyzed oxidation increases up to the temperature range of 50–60 °C then decreases with increasing reaction temperature. The cause for the slow down of the disappearance rate is not known. Based on the kinetic data and reaction products identified, C-1 is found to be more effective as catalyst in the oxidation of 1 and 2 than C-2, but less effective in the oxidation of 3. In the C-1- and C-2-catalyzed oxidation, 1 is oxidized to the corresponding α-carbonyl derivative 4, while 2 readily undergoes epoxidation of the conjugated double bond to produce the corresponding epoxides 5 and 6. The anti-Markovnikov nucleophilic addition of hydroxide and hydroperoxide anions on 5 and 6 then produced α,β-diol 7 and benzaldehyde derivative 8, which are non-catalytic reactions and rate determining steps. The compound 3 also undergoes epoxidation of conjugated aliphatic double bond producing the corresponding epoxide 9. However, none of the corresponding α,β-diol and benzaldehyde derivative is detected in the reaction mixture. In addition, 2 is more susceptible to expoxidation than 3. On the basis of the kinetics and reaction mechanism of the reactions, the catalytic cycles of the C-1- and C-2-catalyzed oxidation of 1–3 are postulated.}, number={1-2}, journal={JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL}, author={Alves, V and Capanema, E and Chen, CL and Gratzl, J}, year={2003}, month={Oct}, pages={37–51} }
 @article{chen_capanema_gracz_2003, title={Comparative studies on the delignification of pine kraft-anthraquinone pulp with hydrogen peroxide by binucleus Mn(IV) complex catalysis}, volume={51}, ISSN={["0021-8561"]}, DOI={10.1021/jf034507f}, abstractNote={Pine kraft-anthraquinone (kraft-AQ) pulp was bleached in alkaline solution with hydrogen peroxide catalyzed by either [L(1)Mn(IV)(micro-O)(3)Mn(IV)L(1)](PF(6))(2)] (C1) or [LMn(IV)(2)(micro-O)(3)] (ClO(4))(2) (C2) at 60 and 80 degrees C for 120 min with a catalyst charge of 10 ppm on pulp. The resulting bleached pulp was hydrolyzed with cellulase to obtain insoluble and soluble residual lignins. The alkaline bleaching effluents were acidified to precipitate alkaline-soluble lignins. These lignin preparations were then characterized by 2D heteronuclear multiple-quantum coherence (HMQC) NMR spectroscopic techniques. The results showed that biphenyl (5-5) and stilbene structures of the residual lignin in the pulp are preferentially degraded in both the C1- and C2-catalyzed bleachings, whereas beta-O-4, beta-5, and beta-beta structures undergo degradation to a lesser extent. In both cases, the degradation of the residual lignin increased with the increase in reaction temperature from 60 to 80 degrees C. Thus, the result of C1-catalyzed delignification is not in agreement with the observed decrease in the disappearance rate for substrates in the C1-catalyzed oxidation of lignin model compounds with hydrogen peroxide when the reaction temperature is increased from 60 to 80 degrees C. In addition, the resulting residual lignins in the C2-catalyzed bleaching at 80 degrees C are less degraded than the corresponding lignins in the C1-catalyzed bleaching at both 60 and 80 degrees C. Thus, C1 is more effective than C2 as catalyst in the binucleus Mn(IV) complex-catalyzed bleaching of pine kraft-AQ pulp with hydrogen peroxide.}, number={21}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Chen, CL and Capanema, EA and Gracz, HS}, year={2003}, month={Oct}, pages={6223–6232} }
 @article{balakshin_capanema_chen_gracz_2003, title={Elucidation of the structures of residual and dissolved pine kraft lignins using an HMQC NMR technique}, volume={51}, ISSN={["1520-5118"]}, DOI={10.1021/jf034372d}, abstractNote={Comparative studies on the structures of residual and dissolved lignins isolated from pine kraft pulp and pulping liquor have been undertaken using the (1)H-(13)C HMQC NMR technique, GPC, and sugar analysis to elucidate the reaction mechanisms in kraft pulping and the lignin reactivity. A modified procedure for the isolation of enzymatic residual lignins has resulted in an appreciable decrease in protein contaminants in the residual lignin preparations (N content < 0.2%). The very high dispersion of HMQC spectra allows identification of different lignin moieties, which signals appear overlapped in 1D (13)C NMR spectra. Elucidation of the role of condensation reactions indicates that an increase in the degree of lignin condensation during pulping results from accumulation of original condensed lignin moieties rather than from the formation of new alkyl-aryl structures. Among aryl-vinyl type moieties, only stilbene structures are accumulated in lignin in appreciable amounts. Benzyl ether lignin-carbohydrate bonds involving primary hydroxyl groups of carbohydrates have been detected in residual and dissolved lignin preparations. Structures of the alpha-hydroxyacid type have been postulated to be among the important lignin degradation products in kraft pulping. The effect of the isolation method on the lignin structure and differences between the residual and dissolved lignins are discussed.}, number={21}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Balakshin, MY and Capanema, EA and Chen, CL and Gracz, HS}, year={2003}, month={Oct}, pages={6116–6127} }
 @article{chen_capanema_gracz_2003, title={Reaction mechanisms in delignification of pine Kraft-AQ pulp with hydrogen peroxide using Mn(IV)-Me4DTNE as catalyst}, volume={51}, ISSN={["0021-8561"]}, DOI={10.1021/jf020992n}, abstractNote={Pine Kraft-AQ pulp was bleached with hydrogen peroxide catalyzed by [LMn(IV)(2) (mu-O)(3)](ClO(4))(2) at 80 degrees C for 120 min under optimum reaction conditions. The resulting bleached pulp was hydrolyzed with cellulase to obtain insoluble and soluble residual lignins. The alkaline effluent from the bleaching was acidified to precipitate alkaline soluble lignin. These lignin preparations were purified, and then analyzed by 2D HMQC NMR spectroscopic techniques. The results showed that biphenyl (5-5) and stilbene structures are preferentially degraded in the bleaching process, while beta-O-4, beta-5, and beta-beta structures undergo degradation only to a lesser extent. This implies that hydrogen peroxide bleaching using the catalyst is more effective in delignification of softwood pulps than hardwood pulps. The possible reaction mechanisms for the delignification of residual lignin in the pine Kraft-AQ pulp in the bleaching process are discussed on the basis of the 2D HMQC NMR spectroscopic data and the model compound experiments.}, number={7}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Chen, CL and Capanema, EA and Gracz, HS}, year={2003}, month={Mar}, pages={1932–1941} }
 @article{capanema_balakshin_chen_gratzl_kirkman_2002, title={Oxidative ammonolysis of technical lignins - Part 3. Effect of temperature on the reaction rate}, volume={56}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2002.063}, abstractNote={Summary}, number={4}, journal={HOLZFORSCHUNG}, author={Capanema, EA and Balakshin, MY and Chen, CL and Gratzl, JS and Kirkman, AG}, year={2002}, pages={402–415} }
 @article{balakshin_chen_gratzl_kirkman_jakob_2001, title={Biobleaching of pulp with dioxygen in laccase-mediator system - effect of variables on the reaction kinetics}, volume={16}, ISSN={["1873-3158"]}, DOI={10.1016/S1381-1177(01)00062-5}, abstractNote={Comparative studies were carried out on the kinetics and mechanism of pulp biobleaching with laccase-mediator system (LMS) with two different mediators, 1-hydroxybenzotriazole (HOBT) and N-hydroxyacetanilide (NHAA). The optimal NHAA and laccase charge was found to be 0.1 mmol and 10 U per gram of pulp with pulp consistency of 10%, at the reaction temperature of 40 °C for 8 h under atmospheric pressure, respectively. The kinetic studies on Kappa number reduction and dioxygen uptake suggest that a very fast rate of delignification with NHAA at the beginning of the process is the result of fast formation of the oxidized mediator species. However, a very slow delignification rate after the initial phase (0.5–1 h) could be caused by low stability of the mediator species. After the reaction time of 2 h, the degree of delignification is higher when HOBT is used as mediator. In contrast to the delignification with NHAA, the formation of the oxidized mediator species is the rate-determining step of the pulp biobleaching with dioxygen in the LMS using HOBT as mediator. Increase in temperature increases the rate of chemical reactions, but decreases the laccase stability. The optimal temperature for pulp biobleaching with HOBT and laccase from Coriolus versicolor is 40 °C. Increasing oxygen pressure improves the efficiency of delignification due to better penetration of the reagents, but does not affect the rate of chemical reactions. The reaction mechanism is discussed based on the kinetic data.}, number={3-4}, journal={JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC}, author={Balakshin, M and Chen, CL and Gratzl, JS and Kirkman, AG and Jakob, H}, year={2001}, month={Dec}, pages={205–215} }
 @article{balakshin_capanema_chen_gratzl_kirkman_gracz_2001, title={Biobleaching of pulp with dioxygen in the laccase-mediator system - reaction mechanisms for degradation of residual lignin}, volume={13}, ISSN={["1873-3158"]}, DOI={10.1016/S1381-1177(00)00225-3}, abstractNote={Pine Kraft-AQ pulp was biobleached with pressurized dioxygen at 40°C in laccase-mediator system (LMS), i.e. in acetate buffer (pH 4.5) containing Coriolus-laccase and 1-hydroxy-benzotriazole (HOBT), the latter being as a mediator. The LMS-treatment was followed by alkaline extraction (E) under standard conditions. The structures of the residual lignins before and after the biobleaching did not differ appreciably. This indicates that only a part of the residual lignin in the pulp undergoes oxidative degradation in the LMS treatment. In contrast, the treatment resulted in strong changes in the structure of the lignin isolated from E-effluents. The 2D HMQC (1H13C correlation) spectra showed the disappearance of β-O-4′, β-β′ and β-5′ bonds in the structure of the alkaline soluble lignin (ASL) from E-effluents, which are present in the 2D spectrum of the original residual lignin (RKL). In addition, the spectra exhibited new signals that are assigned to ArCOOH in biphenyl (5-5′) moieties. This implies that oxidative cleavage of side chains plays an important role in the delignification of pulp. The NMR studies also indicated that intensive degradation of aromatic ring has occurred in the biobleaching. However, premethylation of neither benzyl alcohol nor phenolic hydroxyl groups of the residual lignin in pulp before the biobleaching affected the rate of delignification. The latter indicates that phenolic moieties participate not only in oxidative degradation but also dehydrogenative polymerization reactions in the biobleaching. This is consistent with an appreciable increase in the proportion of fractions with higher molecular mass in lignin isolated from E-effluents.}, number={1-3}, journal={JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC}, author={Balakshin, M and Capanema, E and Chen, CL and Gratzl, J and Kirkman, A and Gracz, H}, year={2001}, month={Apr}, pages={1–16} }
 @article{capanema_balakshin_chen_gratzl_kirkman_2001, title={Oxidative ammonolysis of technical lignins - Part 1. Kinetics of the reaction under isothermal condition at 130 degrees C}, volume={55}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2001.066}, abstractNote={Summary}, number={4}, journal={HOLZFORSCHUNG}, author={Capanema, EA and Balakshin, MY and Chen, CL and Gratzl, JS and Kirkman, AG}, year={2001}, pages={397–404} }
 @article{capanema_balakshin_chen_gratzl_kirkman_2001, title={Oxidative ammonolysis of technical lignins - Part 2. Effect of oxygen pressure}, volume={55}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2001.067}, abstractNote={Summary}, number={4}, journal={HOLZFORSCHUNG}, author={Capanema, EA and Balakshin, MY and Chen, CL and Gratzl, JS and Kirkman, AG}, year={2001}, pages={405–412} }
 @article{capanema_balakshin_chen_gratzl_gracz_2001, title={Structural analysis of residual and technical lignins by H-1-C-13 correlation 2D NMR-spectroscopy}, volume={55}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2001.050}, abstractNote={Summary}, number={3}, journal={HOLZFORSCHUNG}, author={Capanema, EA and Balakshin, MY and Chen, CL and Gratzl, JS and Gracz, H}, year={2001}, pages={302–308} }
 @article{balakskin_chen_gratzl_kirkman_jakob_2000, title={Biobleaching of pulp with dioxygen in the laccase-mediator system. Part 1. Kinetics of delignification}, volume={54}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2000.066}, abstractNote={Summary}, number={4}, journal={HOLZFORSCHUNG}, author={Balakskin, M and Chen, CL and Gratzl, JS and Kirkman, AG and Jakob, H}, year={2000}, pages={390–396} }
 @article{gratzl_chen_2000, title={Chemistry of pulping: Lignin reactions}, volume={742}, journal={Lignin: Historical, biological, and materials perspectives}, publisher={Washington, DC: American Chemical Society}, author={Gratzl, J. S. and Chen, C. L.}, editor={W. G. Glasser, R. A. Northey and Schultz, T. P.Editors}, year={2000}, pages={392–421} }
 @article{potthast_rosenau_kosma_chen_gratzl_2000, title={Confirmation of the presence of formaldehyde and N-(methylene)morpholinium cations as reactive species in the cellulose/NMMO/water system by trapping reactions}, volume={54}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2000.016}, abstractNote={Summary}, number={1}, journal={HOLZFORSCHUNG}, author={Potthast, A and Rosenau, T and Kosma, P and Chen, CL and Gratzl, JS}, year={2000}, pages={101–103} }
 @article{balakshin_chen_gratzl_kirkman_jakob_2000, title={Kinetic studies on oxidation of veratryl alcohol by laccase-mediator system - Part 1. Effects of mediator concentration}, volume={54}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2000.028}, abstractNote={Summary}, number={2}, journal={HOLZFORSCHUNG}, author={Balakshin, MY and Chen, CL and Gratzl, JS and Kirkman, AG and Jakob, H}, year={2000}, pages={165–170} }
 @article{balakshin_chen_gratzl_kirkman_jakob_2000, title={Kinetic studies on oxidation of veratryl alcohol by laccase-mediator system. Part 2. The kinetics of dioxygen uptake}, volume={54}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2000.029}, abstractNote={Summary}, number={2}, journal={HOLZFORSCHUNG}, author={Balakshin, MY and Chen, CL and Gratzl, JS and Kirkman, AG and Jakob, H}, year={2000}, pages={171–175} }
 @article{cui_puthson_chen_gratzl_kirkman_2000, title={Kinetic study on delignification of kraft-AQ pine pulp with hydrogen peroxide catalyzed by Mn(IV)-Me4DTNE}, volume={54}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2000.069}, abstractNote={Summary}, number={4}, journal={HOLZFORSCHUNG}, author={Cui, Y and Puthson, P and Chen, CL and Gratzl, JS and Kirkman, AG}, year={2000}, pages={413–419} }
 @article{chen_potthast_rosenau_gratzl_kirkman_nagai_miyakoshi_2000, title={Laccase-catalyzed oxidation of 1-(3,4-dimethoxyphenyl)-1-propene using ABTS as mediator}, volume={8}, ISSN={["1381-1177"]}, DOI={10.1016/S1381-1177(99)00059-4}, abstractNote={The fungal laccases catalyzed oxidation of 1-(3,4-dimethoxyphenyl)-1-propene (2) with dioxygen in acetate buffer (pH 4.5) producing 1-(3,4-dimethoxyphenyl)propane-1,2-diol (4) and its 1-O-acetyl and 2-O-acetyl derivatives 5 and 6, and 3,4-dimethoxybenzaldehyde (7). However, in phosphate buffer (pH 5.9), the same reaction produced only 4 and 7. When 4 was treated in the same fashion in the phosphate buffer, it was converted into 7 with more than 95 mol% yield. This, together with the formation of 5 and 6 in the acetate buffer, showed that 2 is converted into 3–5 via 1-(3,4-dimethoxyphenyl)propane-1,2-epoxide (3) in the acetate buffer in the presence of ABTS. The major reaction of fungal laccase-catalyzed oxidation of 2 with dioxygen in the presence of ABTS is epoxidation of the double bond conjugated to the aromatic ring.}, number={4-6}, journal={JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC}, author={Chen, CL and Potthast, A and Rosenau, T and Gratzl, JS and Kirkman, AG and Nagai, D and Miyakoshi, T}, year={2000}, month={Feb}, pages={213–219} }
 @article{shiba_xiao_miyakoshi_chen_2000, title={Oxidation of isoeugenol and coniferyl alcohol catalyzed by laccases isolated from Rhus vernicifera Stokes and Pycnoporus coccineus}, volume={10}, ISSN={["1381-1177"]}, DOI={10.1016/S1381-1177(00)00184-3}, abstractNote={Laccases isolated from Rhus vernicifera Stokes (tree) and Pycnoporus coccineus (fungus) catalyzed the oxidation of isoeugenol (1) and coniferyl alcohol (5) in acetone–water (1:1, v/v). These oxidations follow a first order rate law. In general, the rates of Pycnoporus laccase-catalyzed oxidation of 1 and 5 are approximately three and seven times faster than the corresponding rates of Rhus laccase-catalyzed oxidation, respectively. Thus, synthesis for 2-(4-hydroxyphenyl)coumaran type compounds, such as dehydrodiconiferyl alcohol, can be accomplished by Rhus laccase-catalyzed dehydrogenative polymerization of the corresponding 1-(4-hydroxyphenyl)–1-propene derivatives. The reaction proceeds under very mild reaction conditions. The resulting reaction mixtures are chromatographed on a silica gel column to isolate the products in approximately 30–40% yield.}, number={6}, journal={JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC}, author={Shiba, T and Xiao, L and Miyakoshi, T and Chen, CL}, year={2000}, month={Nov}, pages={605–615} }
 @article{alves_drumond_stefani_chen_pilo-veloso_2000, title={Synthesis of new trimeric lignin model compounds containing 5-5 ' and beta-O-4 ' substructures, and their characterization by 1D and 2D NMR techniques}, volume={11}, number={5}, journal={Journal of the Brazilian Chemical Society}, author={Alves, V. L. and Drumond, M. G. and Stefani, G. M. and Chen, C. L. and Pilo-Veloso, D.}, year={2000}, pages={467–473} }
 @article{cui_chen_gratzl_patt_1999, title={A Mn(IV)-Me4DTNE complex catalyzed oxidation of lignin model compounds with hydrogen peroxide}, volume={144}, ISSN={["1381-1169"]}, DOI={10.1016/S1381-1169(99)00042-4}, abstractNote={1-(3,4-dimethoxyphenyl)ethanol, 1-(3,4-dimethoxyphenyl)-1-propene (mixture of E- and Z-isomers) and E-1,2-diphenylethene were chosen as model compounds to investigate the reactivity of lignin toward hydrogen peroxide catalyzed by [L′Mn(IV)(μ-O)3Mn(IV)](ClO4)2 where L′ is 1,2-bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane. All the model compounds investigated were readily oxidized to a significant extent by hydrogen peroxide when catalyzed by this complex. The reaction products were identified by GCMS, and the reaction kinetics was studied. Based on these results, the mechanisms of the reactions have been elucidated. The catalyst preferentially epoxidates C–C double bonds conjugated with aromatic moieties. The activation energy of the reactions was determined.}, number={3}, journal={JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL}, author={Cui, Y and Chen, CL and Gratzl, JS and Patt, R}, year={1999}, month={Aug}, pages={411–417} }
 @misc{rosenau_potthast_kosma_chen_gratzl_1999, title={Autocatalytic decomposition of N-methylmorpholine N-oxide induced by Mannich intermediates}, volume={64}, number={7}, journal={Journal of Organic Chemistry}, author={Rosenau, T. and Potthast, A. and Kosma, P. and Chen, C. L. and Gratzl, J. S.}, year={1999}, pages={2166–2167} }
 @article{ramos_mathias_silva_cotrim_ferraz_chen_1999, title={Characterization of residual lignin after SO2-catalyzed steam explosion and enzymatic hydrolysis of Eucalyptus viminalis wood chips}, volume={47}, ISSN={["1520-5118"]}, DOI={10.1021/jf9810665}, abstractNote={The lignin component found in both water insoluble (WI) and water and alkali insoluble (WIA) fractions derived from SO(2)-impregnated steam-exploded eucalyptus chips (SEE) was isolated and characterized. Dioxane lignins with a sugar content lower than 2% (w/w) were obtained after each material was treated with commercial cellulases. The C9 formulas of both SEE-WI and SEE-WIA dioxane lignins were C(9)H(6.83)N(0.04)O(2.24)(OCH(3))(1.21)(OH(aro))(0.56)(OH(ali))(0. 77) and C(9)H(8.65)N(0.29)O(1.97)(OCH(3))(0.90)(OH(aro))(0. 46)(OH(ali))(1.02), respectively. The weight-average molecular weight (M(w)) of the SEE-WI lignin corresponded to 3.85 kDa, whereas the SEE-WIA lignin had an M(w) of 3.66 kDa for the same polydispersity of 2.4. The SEE-WIA lignin was shown to be more thermally stable than the SEE-WI lignin, requiring temperatures in the range of 520 degrees C for complete degradation. FTIR and (1)H NMR analyses of both untreated and peracetylated lignin fractions showed that (a) the alkali insoluble lignin contained a relatively higher degree of substitution in aromatic rings per C9 unit and that (b) alkaline extraction removed lignin fragments containing appreciable amounts of phenolic hydroxyl groups.}, number={6}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Ramos, LP and Mathias, AL and Silva, FT and Cotrim, AR and Ferraz, AL and Chen, CL}, year={1999}, month={Jun}, pages={2295–2302} }
 @misc{chen_gratzl_kirkman_potthast_rosenau_1999, title={Selective enzymatic oxidation of aromatic methyl groups to aldehydes by oxygen in the presence of a laccase-mediator catalyst}, volume={5,888,787}, number={1999 Mar. 30}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Chen, C. and Gratzl, J. S. and Kirkman, A. G. and Potthast, A. and Rosenau, T.}, year={1999} }
 @inbook{chen_1998, title={Characterization of milled wood lignins and dehydrogenative polymerisates from monolignols by carbon-13 NMR spectroscopy}, booktitle={Lignin and lignan biosynthesis}, publisher={Washington, DC: American Chemical Society}, author={Chen, C. L.}, editor={N. G. Lewis, S. SarkanenEditor}, year={1998}, pages={255–275} }
 @article{kadla_chang_chen_gratzl_1998, title={Reactions of lignin with cyanamide activated hydrogen peroxide Part 1. The degradation of lignin model compounds}, volume={52}, ISSN={["1437-434X"]}, DOI={10.1515/hfsg.1998.52.5.506}, abstractNote={Monomeric lignin model compounds representing various functional groups found in residual lignins were reacted with cyanamide activated hydrogen peroxide. Non-phenolic lignin model compounds failed to react even under extreme reaction conditions (90°C), while phenolic lignin model compounds underwent rapid oxidation. Reaction optimization studies reveal that these reactions are strongly dependent on pH and the cyanamide-to-peroxide ratio, while temperature is not a factor. Through the use of electron paramagnetic resonance (EPR) spectroscopy free radical involvement has been demonstrated. In contrast to previous literature, a predominately free-radical mechanism exists, and on the basis of the reactions carried out in the presence of superoxide dismutase, the presence of .O 2 - has been determined.}, number={5}, journal={HOLZFORSCHUNG}, author={Kadla, JF and Chang, PM and Chen, CL and Gratzl, JS}, year={1998}, pages={506–512} }
 @article{kadla_chang_chen_gratzl_1998, title={Reactions of lignin with cyanamide activated hydrogen peroxide Part 2. The degradation mechanism of phenolic lignin model compounds}, volume={52}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1998.52.5.513}, abstractNote={The reactions of monomeric phenolic lignin model compounds with cyanamide activated hydrogen peroxide were studied. Analyses of the various reaction products indicate four main reactions occur : aromatic hydroxylation, demethoxylation, radical coupling and oxidative ring opening. The predominate products from apocynol and acetoguaiacone were dicarboxylic acid compounds, maleic/fumaric, oxalic and succinic acid derivatives, consistent with degradation by superoxide. In the degradation of creosol, 3-hydroxy-4-methoxy-6-methyl-N-methylaniline was the major compound isolated, providing evidence of a cyanamide radical. Finally, plausible pathways to the formation of superoxide anion and cyanamide oxidation products from alkaline hydrogen peroxide and cyanamide are proposed and their impact on delignification is discussed.}, number={5}, journal={HOLZFORSCHUNG}, author={Kadla, JF and Chang, HM and Chen, CL and Gratzl, JS}, year={1998}, pages={513–520} }
 @misc{roseanu_habicher_chen_1997, title={Preparation of protected amines or alkylated amino acids}, volume={5,684,132}, number={1997 Nov. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Roseanu, T. and Habicher, W. D. and Chen, C. L.}, year={1997} }
 @article{uraki_chen_gratzl_1997, title={Sonolysis of chloro-organics in bleach plant E-1 effluents}, volume={51}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1997.51.5.452}, abstractNote={Degradation of chloro-organics in bleach plant E-1 effluents by ultrasound sonication was investigated to evaluate the effects of ultrasonic treatment on the dechlorination. On sonolysis, ca. 65mol% of 4-chlorophenol (1) at concentration of 1.0x10 -4 M in aqueous solution was decomposed and 35mol% of chlorine in the substrate was released as chloride ions (Cl) alter 80 min at room temperature under atmospheric pressure. By contrast, under the same reaction conditions, only ca. 11mol% and 3mol% of (1) were decomposed at the concentrations of 1.0x10 -3 M and 1.0x10 -2 M with the release of ca. 5 and 1mol% of Cl - , respectively. Although the kinetics for the disappearance of (1) fits a first-order law, the rate constant decreases with increasing initial concentration of the substrate. This suggests that the disappearance rate of (1) does not follow the first order law and the reaction mechanism involved is rather complex. When hydrogen peroxide was added to the solution in the molar ratio of substrate to hydrogen peroxide 1:10, both the rates of degradation and dechlorination were not affected. However, an addition of a smaller amount of hydrogen peroxide to the solution resulted in a decrease in the rate of the degradation. In the presence of hydrogen peroxide, the kinetics for the decomposition of (1) also follows the same pattern for that without hydrogen peroxide. On sonolysis, polychlorinated oxylignins (PCOLs) isolated from E-1 effluent released chloride ions. The high relative mass PCOL released larger amounts of chloride ions than the low relative mass PCOL. The sonolysis brought about a very small decrease in the relative mass of PCOLs, and no significant degradation of PCOLs except for release of chloride ions. This result suggests that an acoustic cavitation by ultrasonic treatment plays a important role in cleavage of C-Cl bonds, but not C-C bonds.}, number={5}, journal={HOLZFORSCHUNG}, author={Uraki, Y and Chen, CL and Gratzl, JS}, year={1997}, pages={452–458} }
 @misc{jividen_chang_reeves_chen_1978, title={Process for obtaining seed hull commodities including cellulosic fibers and xylitol}, volume={4,087,316}, number={1978 May 2}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Jividen, G. M. and Chang, H. M. and Reeves, R. H. and Chen, C. L.}, year={1978} }