- Phosphoric acid-modified commercial kieselguhr supported palladium nanoparticles as efficient catalysts for low-temperature hydrodeoxygenation of lignin derivatives in water
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Efficient production of high value-added chemicals and biofuels via low-temperature chemoselective HDO of lignin derivatives in water is still a challenge. Here, we construct a low-cost, active and stable Pd/PCE catalyst using phosphoric acid-modified commercial Celite (PCE) as the support, and this catalyst exhibits excellent activity in low-temperature HDO of vanillin as well as other lignin derivatives in water. The superior catalytic performance is due to the presence of P species on the surface of Pd/PCE, accelerating the selective conversion of the intermediate into the final product. Detailed experimental and mechanistic studies reveal that the rapid conversion of the intermediate to the final product proceeds via a free-radical process in an interfacial microenvironment created by intimate interacting between the P species and Pd NPs. The insights of this work provide a new low-cost catalytic system for efficient production of valuable chemicals and future biofuels from lignin derivatives. This journal is
- Cui, Yuntong,Liu, Zhaohui,Ran, Jiansu,Wang, Jianjian,Yangcheng, Ruixue
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p. 1570 - 1577
(2022/03/14)
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- Ceria-promoted Co@NC catalyst for biofuel upgrade: synergy between ceria and cobalt species
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Ceria-promoted Co@NC (NC, N doped carbon) catalysts are prepared by pyrolysis of biomass materials. Characterization results indicate that ceria and Co species facilitate the distribution of each other due to the formation of a Ce-O-Co solid solution. The specific surface area of the catalyst increased from 378.77 to 537.7 m2g?1viathe introduction of ceria. The electron transfer from Co to Ce further enhanced their interaction, and Co species facilitate the formation of more defective oxygen vacancies on ceria, which are beneficial to the activities of catalytic hydrogenation and catalytic transfer hydrogenation (CTH), respectively. Thus, Co/Ce@NC (0.99% Co loading) pyrolyzed at 850 °C exhibits excellent performance in the hydrodeoxygenation (HDO) of vanillin with high metal utilization. Catalytic hydrogenation and CTH coexisted in the presence of H2and ethanol, and >99% yield of creosol can be obtained in each of them. The reaction processes are monitored. No intermediate is found in aqueous media, while ethoxymethyl-4-methoxy-2-phenol is detected in ethanol. Moreover, Co/Ce@NC presents outstanding stability and general applicability. This work provides new insights into the construction of M@NC (M, metal) catalysts and the HDO process of biofuel upgrade.
- Wang, Bowei,Gao, Ruixiao,Zhang, Dan,Zeng, Yuyao,Zhang, Fangying,Yan, Xilong,Li, Yang,Chen, Ligong
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supporting information
p. 8541 - 8553
(2021/04/12)
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- Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water
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Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.
- Chen, Chun,Gong, Wanbing,Han, Miaomiao,Wang, Dongdong,Wang, Guozhong,Zhang, Haimin,Zhang, Jifang,Zhang, Yunxia,Zhao, Huijun
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p. 2027 - 2037
(2021/09/02)
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- Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
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Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (~10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
- Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
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p. 3069 - 3084
(2021/11/16)
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- Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
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Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
- Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
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p. 8672 - 8682
(2020/09/18)
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- Profiling of the formation of lignin-derived monomers and dimers from: Eucalyptus alkali lignin
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Lignin is a renewable and the most abundant aromatic source that can be used for extensive chemicals and materials. Although approximately 50 million tons of lignin are produced annually as a by-product of the pulp and paper industry, it is currently underutilized. It is important to know the structural features of technical lignin when considering its application. In this work, we have demonstrated the formation of low-molecular-weight constituents from hardwood (Eucalyptus) lignin, which produces much more low-molecular-weight constituents than softwood (spruce) lignin, after a chemical pulping process, and analyzed the micromolecular compositions in the alkali lignin after fractionation by dichloromethane (DCM) extraction. By applying analytical methods (gel-permeation chromatography, 2D NMR and GC-MS) with the aid of evidence from authenticated compounds, a great treasure trove of lignin-derived phenolic compounds from Eucalyptus alkali lignin were disclosed. Except for some common monomeric products, as many as 15 new lignin-derived monomers and dimers including syringaglycerol, diarylmethane, 1,2-diarylethanes, 1,2-diarylethenes, (arylvinyl ether)-linked arylglycerol dimers and isomeric syringaresinols were identified in the DCM-soluble fraction. Regarding the formation and evolution of the Cα-condensed β-aryl ether structure, a novel route that is potentially responsible for the high content of β-1 diarylethenes and diarylethanes in the lignin low-molecular-weight fraction, in addition to the β-1 (spirodienone) pathway, was proposed. This work not only provides novel insights into the chemical transformation of S-G lignin during the alkali pulping process, but also discovered lignin-derived phenolic monomers and dimers that can potentially be used as raw materials in the chemical or pharmaceutical industries. This journal is
- Hu, Zhenhua,Li, Suxiang,Lu, Fachuang,Shi, Lanlan,Wang, Chen,Yue, Fengxia,Zhang, Han,Zhao, Chengke
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supporting information
p. 7366 - 7375
(2020/11/18)
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- Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen
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The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H2 to a methyl group (-CH3) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.
- Tong, Xinli,Guo, Pengfei,Liao, Shengyun,Xue, Song,Zhang, Haigang
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p. 5828 - 5840
(2019/11/11)
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- Method for selective demethylation of ortho-trimethoxybenzene compounds
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The invention relates to a method for selective demethylation of ortho-trimethoxybenzene compounds and provides a method for preparation of 2,6-dimethoxyphenol derivatives by selective demethylation of ortho-trimethoxybenzene in different substitution types. By taking substitutional or non-substitutional ortho-trimethoxybenzene as a raw material, taking ZrCl4 as a catalyst and taking anisole as an additive, a ratio of the raw material to the catalyst to the additive is optimized in a reaction process to realize selective demethylation at a low reaction temperature ranging from the room temperature to 60 DEG C. The method has the advantages of mild reaction conditions, safety, reliability, low cost and easiness in operation and acquisition of the additive and the catalyst for reaction, simplicity and easiness in separation of reaction products, wide substrate application range and the like. The method effectively improves reaction safety and controllability and has an extensive application prospect in preparation of medicines, material intermediates and fine chemicals.
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Page/Page column 6
(2017/04/03)
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- A ligand-free, powerful, and practical method for methoxylation of unactivated aryl bromides by use of the CuCl/HCOOMe/MeONa/MeOH system
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A ligand-free, powerful, and practical method for mono and polymethoxylation of unactivated aryl bromides has been developed; CuCl was used as catalyst, HCOOMe as cocatalyst, and methanolic MeONa as both nucleophile and solvent. This eco-friendly procedure is characterized by operational simplicity, inexpensive substrates (unactivated mono to polybromoarenes), full conversion, and direct recovery of pure MeOH.
- Guo, Ying,Ji, Si-Zhe,Chen, Cheng,Liu, Hong-Wei,Zhao, Jian-Hong,Zheng, Yu-Lin,Ji, Ya-Fei
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p. 8651 - 8664
(2015/03/05)
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- Catalytic Pulsed Flow Hydrogenation Of Lignin Carboxylic Acid Compounds
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Renewable resources comprising bagasse, corn stover, wood sawdust and switch grass are subject to direct catalytic conversion or bio-fermentation producing ethanol leaving complex lignin compounds for disposal. Chemical conversion of lignin compounds (recoverable from digested lignin) to substituted phenols followed by a carbon steel catalyzed pulsed flow hydrogenation produces cresol and substituted creosol compounds. The pulsed flow process produced close to 100 percent reduction of the reactants compared to 25 percent with continuous flow and is applicable to aliphatic carboxylic acid compounds such as natural oils producing valued liquid hydrocarbons. Specifically reactions are taught for carbon steel catalyzed pulsed flow hydrogenation of lignin carboxylic acids comprising 4-hydroxy-3,5-dimethoxybenzoic acid, 4,5-dihydroxy-3-methoxybenzoic acid, 4-hydroxy-3-methoxybenzoic acid, 4-hydroxybenzoic acid and substituted aliphatic carboxylic acid compounds comprising citric and oleic acids in contact with a promoter comprising an anhydrous sodium sulfate and an activator comprising Co(II)-Co(III)-Co(II) using hydrogen gas at 225° C. to 350° C. and ambient to 10 atmospheres pressure.
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Paragraph 0023
(2015/02/18)
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- Catalytic reduction of lignin acids and substituted aliphatic carboxylic acid compounds
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Renewable resources comprising bagasse, corn stover, wood sawdust and switch grass are subject to direct catalytic conversion or bio-fermentation processes producing ethanol and organic by products leaving complex lignin compounds as waste for disposal. Chemical conversion of lignin compounds to aromatic lignin acids followed by reductive hydrogenation to cresol and substituted creosol compounds prepares these natural resources for chemical conversion to a form of gasoline and valued industrial compounds. The process disclosed herein is also applicable to organic carboxylic acid compounds such as natural oils producing valued liquid hydrocarbon fuels. Specifically catalytic reactions are taught for reductive chemical hydrogenation of lignin acids comprising 4-hydroxy-3,5-dimethoxybenzoic acid, 4,5-dihydroxy-3-methoxybenzoic acid, 4-hydroxy-3-methoxybenzoic acid, 4-hydroxybenzoic acid and substituted aliphatic carboxylic acid comprising citric and oleic acid compounds in contact with an iron or steel metal surface, a promoter comprising an alkali metal sulfate and a catalyst comprising Co(II)—Co(III) or Mn(II)—Co(III) compound using hydrogen gas at ambient to 10 atmospheres pressure. This process readily forms valued organic compounds from waste natural materials thereby increasing their value.
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Page/Page column 3
(2012/05/21)
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- An expeditious synthesis of syringaldehyde from para-cresol
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Syringaldehyde is prepared from p-cresol via a three step reaction sequence in overall yield of 63-67%. The synthesis involves selective bromination followed by high pressure and temperature methoxilation and catalytical oxidation. The use of copper chloride in different oxidation state as a catalyst in two key steps i.e. methoxilation in aromatic ring (by cuprous chloride) and oxidation of aromatic methyl to aldehyde (by cupric chloride) underscore fidelity of the process.
- Tripathi,Sama,Taneja
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experimental part
p. 379 - 381
(2010/10/18)
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- Selective demethylation and debenzylation of aryl ethers by magnesium iodide under solvent-free conditions and its application to the total synthesis of natural products
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An efficient selective demethylation and debenzylation method for aryl methyl/benzyl ethers using magnesium iodide under solvent-free conditions has been developed and applied to the synthesis of natural flavone and biphenyl glycosides. A variety of functional groups including glycoside were tolerated under the reaction conditions. Experimental results indicated that the removal of an O-benzyl group was easier than that of an O-methyl group, regardless of wherever they were meta or para to the carbonyl. Thus selective debenzylation can be achieved for substrates bearing both benzyloxy and methoxy groups.
- Bao, Kai,Fan, Aixue,Dai, Yi,Zhang, Liang,Zhang, Weige,Cheng, Maosheng,Yao, Xinsheng
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scheme or table
p. 5084 - 5090
(2010/04/03)
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- Preparation of monodentate phosphinite ligands: their applications in palladium catalyzed Suzuki reactions
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Two phosphinites 2,6-OMe, 4-Me, 1-OPR2C6H2 (5a: R=Ph; 5b: R=tBu) were prepared in good yields. Two methoxy groups are placed on the 2,6 positions of the phosphinites deliberately thereby to avoid a plausible orthometallation process while coordinating toward palladium metal. Further reaction of 5a with PdCl2 in the ratio of 2:1 and 1:1 gave 5a ligated palladium complexes {(5a)PdCl(μ-Cl)}2 7a and {(5a)2PdCl2} 8a, respectively. As revealed from their crystal structures, the former is a dimeric complex with anticipated molecular arrangement; nevertheless, the latter is a monomeric complex with unexpected, energetically unfavorable cis form. By contrast, only dimeric form was observed from the reaction of 5b with PdCl2. It is believed that the bulky substituents, tBu, on 5b prevent the formation of a monomeric complex in cis form. Fair to good efficiencies were observed for the Suzuki-Miyaura cross-coupling reactions employed in situ-prepared 5/Pd(OAc)2 as the catalytic precursor.
- Cheng, Yan-Huei,Weng, Chia-Ming,Hong, Fung-E.
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p. 12277 - 12285
(2008/03/14)
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- New convenient synthesis of iridol. An approach to the synthesis of ubiquinones
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A strategy for the synthesis of ubiquinones, in which iridol is the key intermediate, has been developed, together with a new convenient synthesis of iridol (2,3-dimethoxy-5-methylphenol) starting from the easily available 4-methylphenol and using mild conditions and friendly and high-yielding reactions.
- Bovicelli, Paolo,Antonioletti, Roberto,Barontini, Maurizio,Borioni, Giorgio,Bernini, Roberta,Mincione, Enrico
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p. 1255 - 1257
(2007/10/03)
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- Determination of methoxyphenols in ambient atmospheric particulate matter: Tracers for wood combustion
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Combustion of wood and other biomass fuels produces source-specific organic compounds arising from pyrolysis of lignin, including substantial amounts of 4-substituted methoxylated phenolic compounds (methoxyphenols). These compounds have been used as atmospheric markers to determine the contribution of wood smoke to ambient atmospheric fine particulate matter (PM). However, reliable quantification of methoxyphenols represents an analytical challenge because these compounds are polar, semivolatile, and somewhat reactive. We report herein an improved gas chromatographic-mass spectrometric (GC/MS) method for the sensitive and reliable determination of methoxyphenols in low-volume ambient PM samples. Deuterated standard compounds are added to the environmental samples prior to extraction to determine analyte recoveries in each sample. Analytical figures of merit for the assay, as applied to ambient PM2.5 and PM10 samples are as follows: recovery = 63-100%; precision = 2-6%; analytical limit of detection (S/N 2) = 0.002 μg/mL; limit of quantitation = 0.07-0.45 ng/m3 (assuming a 14 m3 sample). The improved method was applied to ambient PM samples collected between 1999 and 2000 in Seattle, WA. Particle-bound methoxyphenol concentrations in the range 3 were observed and the methoxyphenols were present almost exclusively in the fine (PM2.5) size fraction. We also demonstrated that XRF analysis of samples of atmospheric PM collected on Teflon filters significantly reduced the levels of methoxyphenols measured in the PM samples in subsequent assay of the same filters. Therefore, XRF analysis of filters, commonly undertaken to obtain trace element concentrations for use in source apportionment analyses, would preclude the subsequent analysis of those filters for methoxyphenols and other similarly semivolatile or reactive organic chemicals.
- Simpson, Christopher D.,Paulsen, Michael,Dills, Russell L.,Liu, L.-J. Sally,Kalman, David A.
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p. 631 - 637
(2007/10/03)
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- Fine particle and gaseous emission rates from residential wood combustion
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Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning-communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter(a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and se mivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8- C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and forts were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography. Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter (a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and semivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8-C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence, and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and ions were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography.
- Mcdonald, Jacob D.,Zielinska, Barbara,Fujita, Eric M.,Sagebiel, John C.,Chow, Judith C.,Watson, John G.
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p. 2080 - 2091
(2007/10/03)
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- Evaluation of acute toxicity and genotoxicity of liquid products from pyrolysis of Eucalyptus grandis wood
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Slow pyrolysis of Eucalyptus grandis wood was performed in an oven laboratory, and smoke was trapped and condensed to yield liquid products. Polycyclic aromatic hydrocarbons (PAHs) and phenolic fractions were isolated from the former liquid products using adsorption column chromatography (ACC) and identified by GC/MS. Concentrations of PAH and phenolic fractions in total pyrolysis liquids were respectively 48.9 μg/g and 8.59% (w/w). Acute toxicity of total samples of pyrolysis liquids and the phenolic fraction was evaluated by means of two bioassays, namely, 24-h immobilization bioassay with Daphnia magna and Microtox(TM) bioassays, the latter employing the luminescent bacteria Photobacterium phosphoreum. Total pyrolysis liquids and the PAH fraction were evaluated for genotoxicity by the Microtox(TM) bioassay conducted using rehydrated freeze-dried dark mutant of the luminescent bacteria Vibrio fisheri strain M169. Total pyrolysis liquids and the phenolic fraction, respectively, in concentrations of 170 and 68 mg/L were able to immobilize 50% (EC50) of the D. magna population following 24-h exposure. Concentrations of 19 and 6 mg/L, respectively, for total pyrolysis liquids and phenolic fraction were the effective concentrations that resulted in a 50% (EC50) reduction in light produced by bacteria in the Microtox(TM) bioassay. Accordingly, the Microtox(TM) bioassay was more sensitive to toxic effects of both kind of samples than the D. magna bioassay, particularly for the phenolic fraction. Regarding to the genotoxicity evaluation, the results achieved by Microtox(TM) bioassay showed that total pyrolysis liquids had no genotoxic effects with and without exogenous metabolic activation using rat liver homogenate (S9). However, the PAH fraction showed toxic effects with rat liver activation and had a dose-response number (DRN) equal to 1.6, being in this way suspected genotoxic. The lowest detected concentration (LDC) of the PAH fraction able to cause genotoxic effects was 375 μg/L.
- Pimenta,Bayona,Garcia,Solanas
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p. 169 - 175
(2007/10/03)
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- LiAIH4 promoted reductive deoxygenation of hydroxybenzyl alcohols via benzoquinone methide intermediates
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Primary and secondary hydroxybenzyl alcohols react with LiAIH4 in chlorobenzene to give the corresponding alkylphenols. The reaction proceeds through the formation of benzoquinone methide as an intermediate. An example of [4+2] cycloaddition of benzoquinone methide is also reported.
- Baik, Woonphil,Lee, Hyun Joo,Koo, Sangho,Kim, Byeong Hyo
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p. 8125 - 8128
(2007/10/03)
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- Process for producing alkylphenols
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There is disclosed a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of (a) an alkaline or alkaline earth metal catalyst selected from a hydroxide of an alkaline metal, hydroxide of an alkaline earth metal, a carbonate of an alkaline metal, and a hydrogencarbonate of an alkaline metal and (b) a hydrogenation catalyst. By the use of the process, the alkylphenols can be produced in good yield in one stage method.
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- Process for producing alkylphenols
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There is disclosed a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of (a) an alkaline or alkaline earth metal catalyst selected from a hydroxide of an alkaline metal, hydroxide of an alkaline earth metal, a carbonate of an alkaline metal, and a hydrogencarbonate of an alkaline metal and (b) a hydrogenation catalyst. By the use of the process, the alkylphenols can be produced in good yield in one stage method.
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- Preparation of p-hydroxybenzaldehyde derivatives
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A 4-hydroxybenzaldehyde derivative of the formula: STR1 wherein each of R1, R2, R3 and R4 is selected from the group consisting of hydrogen atom, halogen atoms, lower alkyl groups or lower alkoxy groups, which is useful as intermediate for the production of medicines or agricultural chemicals, or as flavor, is produced by the reaction of a p-cresol derivative of the formula: STR2 wherein each of R1, R2, R3 and R4 is as defined above, with oxygen or oxygen-containing gas in the presence of a base and a catalytic amount of cobalt compound or metallic cobalt.
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- Process for aromatic ethers
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A process for the preparation of aromatic ethers by the bromination of a compound of the formula STR1 wherein R1, independently, is hydrogen, hydroxy, lower alkoxy, lower alkyl; m is an integer from 1-4, and A is --CHO, --COOR3 or lower alkyl, and subsequently treating the reaction product of the bromination step with an alkali metal alkoxide in the presence of cuprous halide or oxide, is described.
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- Protodemethoxylation of 1,2,3-Trimethoxybenzenes and a Simple Synthesis of 3,5-Dimethoxybenzoic Acid
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Bouveault-Blanc reduction of some 1,2,3-trimethoxybenzene derivatives has been found to result in the loss of central methoxy group.It is thus possible to prepare 3,5-dimethoxybenzoic acid from 3,4,5-trimethoxybenzoic acid.A possible mechanism for the regiospecific demethoxylation in these compounds is suggested.
- Sharda, Rekha,Krishnamurty, H. G.
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p. 405 - 406
(2007/10/02)
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