- Oxidation of but-3-en-1,2-diol: Green access to hydroxymethionine intermediate
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Supported metallic and bimetallic systems were used for the selective oxidation of but-3-en-1,2-ol (BDO) to hydroxybut-3-en-2-one (HBO), an intermediate in the hydroxymethionine synthesis. All catalysts were active in this reaction. However, bimetallic systems were found more active and selective to HBO in the liquid aqueous phase at 50 °C using molecular O2 as a benign oxidant. The best performance (87% BDO conversion and 88% HBO selectivity) was observed over a 2%PdPt/TiO2 catalyst. No metal leaching was observed under the conditions studied.
- Grasset,Rey,Bellière-Baca,Araque,Paul,Dumeignil,Wojcieszak,Katryniok
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- Oxidation of 3-butene-1,2-diol by alcohol dehydrogenase
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3-Butene-1,2-diol(BDD)is a metabolite of the carcinogenic petrochemical 1,3-butadiene. BDD is produced by cytochrome P450-mediated oxidation of 1,3- butadiene to butadiene monoxide, followed by enzymatic hydrolysis by epoxide hydrolase. The metabolic disposition of BDD is unknown. The current work characterizes BDD oxidation by purified horse liver alcohol dehydrogenase (ADH) and by cytosolic ADH from mouse, rat, and human liver. BDD is oxidized by purified horse liver ADH in a stereoselective manner, with (S)-BDD oxidized at approximately 7 times the rate of (R)-BDD. Attempts to detect and identify metabolites of BDD using purified horse liver ADH demonstrated formation of a single stable metabolite, 1-hydroxy-2-butanone (HBO). A second possible metabolite, 1-hydroxy-3-butene-2-one (HBONE), was tentatively identified by GC/MS, but HBONE formation could not be clearly attributed to BDD oxidation, possibly due to its rapid decomposition in the incubation mixture. Formation of HBO by ADH was dependent upon reaction time, protein concentration, substrate concentration, and the presence of NAD. Inclusion of GSH or 4-methylpyrazole in the incubation mixture resulted in inhibition of HBO formation. Based on these results and other lines of evidence, a mechanism is proposed for HBO formation involving generation of several potentially reactive intermediates which could contribute to toxicity of 1,3- butadiene in exposed individuals. Comparison of kinetics of BDD oxidation in rat, mouse, and human liver cytosol did not reveal significant differences in catalytic efficiency (V(max)/K(m)) between species. These results may contribute to a better understanding of 1,3-butadiene metabolism and toxicity.
- Kemper, Raymond A.,Elfarra, Adnan A.
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- Enantioselective Cascade Biocatalysis for Deracemization of Racemic β-Amino Alcohols to Enantiopure (S)-β-Amino Alcohols by Employing Cyclohexylamine Oxidase and ω-Transaminase
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Optically active β-amino alcohols are very useful chiral intermediates frequently used in the preparation of pharmaceutically active substances. Here, a novel cyclohexylamine oxidase (ArCHAO) was identified from the genome sequence of Arthrobacter sp. TYUT010-15 with the R-stereoselective deamination activity of β-amino alcohol. ArCHAO was cloned and successfully expressed in E. coli BL21, purified and characterized. Substrate-specific analysis revealed that ArCHAO has high activity (4.15 to 6.34 U mg?1 protein) and excellent enantioselectivity toward the tested β-amino alcohols. By using purified ArCHAO, a wide range of racemic β-amino alcohols were resolved, (S)-β-amino alcohols were obtained in >99 % ee. Deracemization of racemic β-amino alcohols was conducted by ArCHAO-catalyzed enantioselective deamination and transaminase-catalyzed enantioselective amination to afford (S)-β-amino alcohols in excellent conversion (78–94 %) and enantiomeric excess (>99 %). Preparative-scale deracemization was carried out with 50 mM (6.859 g L?1) racemic 2-amino-2-phenylethanol, (S)-2-amino-2-phenylethanol was obtained in 75 % isolated yield and >99 % ee.
- Zhang, Jian-Dong,Chang, Ya-Wen,Dong, Rui,Yang, Xiao-Xiao,Gao, Li-Li,Li, Jing,Huang, Shuang-Ping,Guo, Xing-Mei,Zhang, Chao-Feng,Chang, Hong-Hong
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p. 124 - 128
(2020/09/21)
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- Palladium-Catalyzed (3+3) Annulation of Allenylethylene Carbonates with Nitrile Oxides
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In this paper, we designed and synthesized a new type of cyclic carbonates, allenylethylene carbonates (AECs). With AECs as reactive precursors, we developed palladium-catalyzed (3+3) annulation of AECs with nitrile oxides. Various AECs worked well in this reaction under mild reaction conditions. A variety of 5,6-dihydro-1,4,2-dioxazine derivatives with allenyl quaternary stereocenters can be accessed in a facile manner in high yields (≤98%).
- Pan, Ting,Gao, Xing,Yang, Sen,Wang, Lan,Hu, Yimin,Liu, Min,Wang, Wei,Wu, Yongjun,Zheng, Bing,Guo, Hongchao
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supporting information
p. 5750 - 5754
(2021/08/16)
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- A mechanism study on the efficient conversion of cellulose to acetol over Sn-Co catalysts with low Sn content
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Efficient conversion of renewable cellulose to high value-added C3 chemicals is a great challenge in the field of biomass valorization. In this work, we found that the combination of Co and Sn could significantly improve the efficiency of cellulose conversion to acetol. 54.4% yield of acetol and 66.6% total yield of C3 products were obtained when using 2%Sn-10%Co/SiO2 (2 wt% Sn content) as a catalyst. However, using the same Sn content of 2%Sn-10%Ni/SiO2, no acetol and only 7.1% yield of C3 products were produced. By studying the effects of different Sn and Co concentrations on cellulose conversion, it was found that the Sn species play an important role in catalyzing glucose conversion to C3 intermediates, while Co mainly played a role in hydrogenation, the same as Ni. The study demonstrated that Sn-Co/SiO2 with low Sn content can convert glucose to C3 intermediates more efficiently than the Sn-Ni/SiO2 catalyst. Moreover, Sn-Co/SiO2 could effectively convert C3 intermediates to acetol at a high temperature which is essential for acetol production from cellulose; but under the same conditions, the Sn-Ni/SiO2 catalyst tended to catalyze the polymerization of C3 intermediates. A series of characterization methods including AAS, TEM, HRTEM, EDS, XRD, ex situ XPS, in situ XPS, and CO2-TPD found that the combination of Sn and Co could significantly increase the noninteger valent SnOx species in the catalyst. These species increased the basicity of the catalyst and were beneficial in catalyzing the isomerization of glucose and the retro-aldol condensation of fructose. This journal is
- Liu, Xiaodong,Liu, Xiaohao,Ma, Longlong,Wang, Haiyong,Xiao, Tianci,Zhang, Ying
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p. 6579 - 6587
(2020/11/16)
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- Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
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The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
- Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
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p. 4227 - 4237
(2020/05/05)
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- Preparation method of 1-hydroxyl-2-alkanone
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The invention discloses a preparation method of 1-hydroxyl-2-alkanone. According to the preparation method, dihydric alcohol is converted into 1-hydroxy-2-alkanone in the presence of a copper-based catalyst (a conversion step). The reaction conditions of the conversion step are as follows: the reaction temperature is 200-400 DEG C, the reaction pressure is 0.01-0.5 MPa, and the liquid hour space velocity is 0.1-10 h. The method has a high dihydric alcohol conversion rate and 1-hydroxyl-2-alkanone selectivity, and is easy for industrial implementation.
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Paragraph 0033-0034; 0042; 0046-0047
(2020/07/12)
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- Highly efficient catalytic conversion of cellulose into acetol over Ni-Sn supported on nanosilica and the mechanism study
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Selective conversion of cellulose into high value-added C3 chemicals is a great challenge in biorefinery due to the complicated reaction process. In this work, 61.6% yield of acetol was obtained by one pot conversion of cellulose using Ni-Sn/SiO2 catalysts. A series of characterization methods including TEM, STEM-HAADF, EDS, AAS, XRD, XPS, H2-TPR, Py-FTIR, and CO2-TPD were carried out to explore the structure-activity relationship. The strong basicity of the catalysts was a key factor affecting the production of acetol. In addition, catalysts with the hydrothermally stable L-acid sites and no B-acid sites inhibited side reactions and ensured efficient conversion of cellulose into small molecules. Further studies showed that the formation of the Ni3Sn4 alloy significantly promoted the acetol production, and its weak hydrogenation activity inhibited further conversion of acetol. Noninteger valence tin species (Snδ+ and SnOx) were formed both in Ni3Sn4 and Sn/SiO2. These Sn species were the source of basic sites and the active sites for catalyzing cellulose to acetol. Under the synergistic catalysis of Sn/SiO2 and the Ni3Sn4 alloy, cellulose was efficiently converted into acetol. This work provides guidance for the selective conversion of cellulose into C3 products.
- Liu, Xiaohao,Liu, Xiaodong,Xu, Guangyue,Zhang, Ying,Wang, Chenguang,Lu, Qiang,Ma, Longlong
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p. 5647 - 5656
(2019/11/05)
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- Selective Conversion of Cellulose to Hydroxyacetone and 1-Hydroxy-2-Butanone with Sn–Ni Bimetallic Catalysts
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The high-value-added chemicals hydroxyacetone (HA) and 1-hydroxy-2-butanone (HB) were produced from agricultural waste over a Ni3Sn4-SnOx catalyst. The Sn–Ni intermetallic compound and SnOx acted as the active sites for HA and HB production by selectively cleaving the target C?C and C?O bonds. Approximately 70 % of the total HA and HB yield was obtained by selective hydrogenolysis of cellulose. This strategy expands the application of cellulose towards renewable production of high-value C3 and C4 keto-alcohols from cellulosic biomass.
- Wang, Haiyong,Zhu, Changhui,Liu, Qiying,Tan, Jin,Wang, Chenguang,Liang, Zheng,Ma, Longlong
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p. 2154 - 2160
(2019/03/21)
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- Well-dispersed nickel nanoparticles on the external and internal surfaces of SBA-15 for hydrocracking of pyrolyzed α-cellulose
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Catalysts comprising nickel supported on SBA-15 were prepared by wet impregnation and co-impregnation methods. Wet impregnation was performed by directly dispersing an Ni(NO3)2·6H2O aqueous solution into SBA-15, whereas in co-impregnation, ethylene glycol (EG) was added to nickel nitrate aqueous solution prior to dispersion into SBA-15. After drying and calcination, NiO/SBA-15w and NiO/SBA-15c were produced. Later, after the reduction process, Ni/SBA-15w and Ni/SBA-15c were obtained. The prepared catalysts were evaluated for the hydrocracking of pyrolyzed α-cellulose. The TEM images revealed that the catalysts prepared by wet impregnation showed inhomogeneous distribution of nickel loading, whereas catalysts prepared by co-impregnation using EG exhibited homogeneous distribution and formed no nickel aggregates. During hydrocracking of pyrolyzed α-cellulose, Ni/SBA-15c with total acidity, nickel loading, particle size, and specific surface area of 7.27 m mol g?1, 5.20 wt%, 3.17 nm, and 310.0 m2 g?1, respectively, exhibited the best catalytic performance compared to other prepared catalysts with 67.35 wt% conversion of liquid product with maximum selectivity in producing 13.09 wt% of 3-methyl-pentane. Moreover, Ni/SBA-15w with total acidity, nickel loading, particle size, and specific surface area of 10.87 m mol g?1, 8.15 wt%, 7.01 nm, and 628.0 m2 g?1, respectively, produced 69.89 wt% liquid product without hydrocarbons. Study of selectivity towards the formation of liquid hydrocarbons was carried out via double step hydrocracking using Ni/SBA-15w, and 18.55 wt% of n-hexane was produced in the liquid product.
- Trisunaryanti, Wega,Suarsih, Endah,Triyono,Falah, Iip Izul
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p. 1230 - 1237
(2019/01/23)
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- Asymmetric ring opening of racemic epoxides for enantioselective synthesis of (S)-β-amino alcohols by a cofactor self-sufficient cascade biocatalysis system
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A novel one-pot epoxide hydrolase/alcohol dehydrogenase/transaminase cascade process for the asymmetric ring opening of racemic epoxides to enantiopure β-amino alcohols is reported. The product (S)-β-amino alcohols were obtained in 97-99% ee and 79-99% conversion from readily available racemic epoxides.
- Zhang, Jian-Dong,Yang, Xiao-Xiao,Jia, Qiao,Zhao, Jian-Wei,Gao, Li-Li,Gao, When-Chao,Chang, Hong-Hong,Wei, Wen-Long,Xu, Jian-He
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- Hydrothermally Stable Ruthenium–Zirconium–Tungsten Catalyst for Cellulose Hydrogenolysis to Polyols
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In this work, we describe a catalytic material based on a zirconium–tungsten oxide with ruthenium for the hydrogenolysis of microcrystalline cellulose under hydrothermal conditions. With these catalysts, polyols can be produced with high yields. High and stable polyol yields were also achieved in recycling tests. A catalyst with 4.5 wt % ruthenium in total achieved a carbon efficiency of almost 100 %. The prepared Zr-W oxide is mesoporous and largely stable under hydrothermal conditions (493 K and 65 bar hydrogen). Decomposition into the components ZrO2 and WO3 could be observed at temperatures of 1050 K in air.
- Lucas, Martin,Fabi?ovicová, Katarina,Claus, Peter
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p. 612 - 618
(2017/12/28)
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- The ketol compound
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PROBLEM TO BE SOLVED: To provide a method for producing from alcohol having at least a primary hydroxyl group and a secondary hydroxyl group a corresponding ketol compound selectively at a high yield using a heterogeneous catalyst capable of being easily separated and recovered from a reaction product and being reused.SOLUTION: In a method for producing a ketol compound, alcohol having at least a primary hydroxyl group and a secondary hydroxyl group is oxidized in the presence of a copper catalyst supported on a carrier to produce a corresponding ketol compound. Glycerol is preferable as the alcohol having at least a primary hydroxyl group and a secondary hydroxyl group, and dihydroxyacetone is preferable as the corresponding ketol compound.
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Paragraph 0051; 0055
(2017/05/20)
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- Efficient microwave-assisted synthesis of hydroxymethyl ketones using NHC organocatalysts
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Hydroxymethyl ketones are useful auxiliaries in organic synthesis and are also found in several medicinal agents. N-Heterocyclic carbenes (NHCs) have been used in the literature in order to introduce the hydroxymethyl group into aromatic aldehydes in good yields, but they are not that successful for aliphatic aldehydes. In the present work, the use of microwave irradiation has been efficiently incorporated into this organocatalytic synthesis of aromatic, but more importantly of aliphatic hydroxymethyl ketones that can be used as precursors for medicinally interesting compounds.
- Nikolaou, Aikaterini,Kokotos, George,Magrioti, Victoria
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p. 7628 - 7632
(2016/11/11)
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- Catalytic dehydrogenation of 1,2- and 1,3-diols
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Described are studies of the dehydrogenation of 1,2- and 1,3-diols in homogenous solutions catalyzed by {[2,5-diphenyl-3,4-ditoluyl-(η5-C4CO)]2H}Ru2(CO)4(μ-H) (otherwise known as the Casey/Shvo catalyst). Both in the presence and absence of a dihydrogen acceptor, these reactions led to the analogous α-hydroxyketone as the only organic product. Isotopic labeling studies indicate that this product arises from reversible dehydrogenation/hydrogenation reactions, resulting in formation of the thermodynamically favored α-hydroxyketone. When this catalytic dehydrogenation was carried out in the presence of the rhodium decarbonylation catalyst Rh(dppp)2Cl (dppp = 1,3-bis(diphenylphosphino)propane), modest amounts of carbon monoxide result, suggesting that the dehydrogenation does generate at least some aldehydes that are intercepted by this catalyst. However, the efficiency of the latter reaction is poor.
- Weber, Madeline A.,Ford, Peter C.
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supporting information
p. 81 - 87
(2016/04/05)
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- Modular synthesis of dihydroxyacetone monoalkyl ethers and isosteric 1-hydroxy-2-alkanones
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Straightforward methods for the efficient, systematic preparation of libraries of the title compound classes have been evaluated. A general and efficient modular route to dihydroxyacetone monoethers was developed based on trityl glycidol, which, through epoxide opening, oxidation, and deprotection, provided variously alkylated ethers by three routine operations in good overall yields (eight examples, 24-59 %). The preparation of structurally related 1-hydroxyalkanones depends on the availability of the most economic starting materials and on their physicochemical properties. Thus, the most practical one-step approaches consisted of the sec-selective oxidation of short-chain 1,2-diols (≤ C6) using NaOCl, and the direct ketohydroxylation of 1-alkenes (≥ C6) using buffered stoichiometric KMnO4 or catalytic RuO4 with reoxidation by oxone, for which mostly good overall yields were achieved on a multigram scale (nine examples, 15-78 %).
- Güclü, Deniz,Rale, Madhura,Fessner, Wolf-Dieter
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supporting information
p. 2960 - 2964
(2015/04/27)
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- Synthesis of α-hydroxy ketones from vicinal diols by selective dehydrogenation over Ir-ReOx/SiO2 catalyst
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Rhenium oxide-modified Ir/SiO2 (Ir-ReOx/SiO 2) catalyst shows high activity and selectivity for the dehydrogenation of trans-1,2-cyclohexanediol to 2-hydroxycyclohexanone in water solvent under Ar. Linear vicinal diols bearing two secondary hydroxy groups or both a primary hydroxy group and a secondary hydroxy group can also be transformed to the corresponding α-hydroxy ketones in high selectivities. Ir-ReOx/SiO2 can be reused at least four times without loss of activity and selectivity.
- Sato, Hiraku,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
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supporting information
p. 334 - 336
(2014/03/21)
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- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
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The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 6055 - 6058
(2015/03/30)
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- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
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The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 6055 - 6058
(2014/12/10)
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- Chemoselective, iron(ii)-catalyzed oxidation of a variety of secondary alcohols over primary alcohols utilizing H2O2 as the oxidant
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A mild, iron-based catalyst system is presented that selectively oxidizes secondary alcohols to the corresponding hydroxy ketones in the presence of primary alcohols within 15 minutes at room temperature, utilizing H 2O2 as the oxidant.
- Lenze, Matthew,Bauer, Eike B.
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supporting information
p. 5889 - 5891
(2013/07/19)
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- METHOD FOR MANUFACTURING KETONE
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A method for manufacturing a ketone, includes oxidizing an internal olefin or a cyclic olefin having a functional group containing a hetero atom and one carbon-carbon double bond or more at a position other than terminals of a molecule thereof in an amide-based solvent in the presence of water, a palladium catalyst, and molecular oxygen, without oxidizing the functional group, thereby bonding an oxo group to at least one of the carbon atoms constituting the carbon-carbon double bond. The amide-based solvent is represented by formula (1): wherein R1 represents an alkyl group having 1 to 4 carbon atoms; R2 and R3 each independently represent an alkyl group having 1 to 4 carbon atoms or an aryl group; and when R1 and R2 are alkyl groups, R1 and R2 may be bonded to each other to form a ring structure.
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Page/Page column 9
(2012/08/08)
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- PROCESS INCLUDING HYDROGENOLYSIS OF BIOMASS FOLLOWED BY DEHYDROGENATION AND ALDOL CONDENSATION FOR PRODUCING ALKANES
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A method comprises providing a bio-based feedstock; contacting the bio-based feedstock with a solvent in a hydrolysis reaction to form an intermediate stream comprising carbohydrates; contacting the intermediate stream with an aqueous phase reforming catalyst to form a plurality of oxygenated intermediates, wherein a first portion of the oxygenated intermediates are recycled to form the solvent; and contacting at least a second portion of the oxygenated intermediates with a condensation catalyst comprising a base functionality to form a fuel blend.
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Page/Page column 34-37
(2011/12/02)
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- Rate constants for the gas-phase reactions of OH radicals with a series of hydroxyaldehydes at 296 ± 2 K
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Using a relative rate method with in situ generation of the hydroxyaldehydes, rate constants for the reactions of the OH radical with 2-hydroxybutanal [CH3CH2CH(OH)CHO], 3-hydroxybutanal [CH3CH(OH)CH2CHO], 2-hydroxypropanal [CH 3CH(OH)CHO], 2-hydroxy-2-methylpropanal [(CH3) 2C(OH)CHO], and 3-hydroxy-propanal [HOCH2CH 2CHO] have been measured at atmospheric pressure and 296 ± 2 K. The hydroxy-aldehydes were generated in situ from the OH radical-initiated reactions of precursor compounds (1,2- and 1,3-butanediol, 2-methyl-2,4-pentanediol, 2-methyl-3-buten-2-ol, and cis-3-hexen-1-ol) and the rate constants for the reaction of OH radicals with the hydroxyaldehydes were determined relative to those for reaction of OH radicals with the precursor compound. The rate constants obtained (in units of 10-11 cm 3 molecule-1 s-1) were CH3CH 2CH(OH)CHO, 2.37 ± 0.23; CH3CH(OH)CH 2CHO, 2.95 ± 0.24; CH3CH(OH)CHO, 1.70 ± 0.20; (CH3)2C(OH)CHO, 1.40 ± 0.25; and HOCH 2CH2CHO, 1.99 ± 0.29.
- Baker, Jillian,Arey, Janet,Atkinson, Roger
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p. 7032 - 7037
(2007/10/03)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Oxidation of ketone by palladium(II), α-hydroxyketone synthesis catalyzed by a bimetallic palladium(II) complex
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A bimetallic palladium(II) complex containing a triketone ligand and a bridging dinitrogen ligand oxidizes ketones in aqueous THF to α-hydroxyketone by a direct air oxidation. While the normal synthesis of α-hydroxyketones involves a series of reactions, this synthesis performs the transformation in one step in a catalytic air oxidation. This synthesis does not involve an olefin and is almost unprecedented in transition metal catalysis. Its main virtue is its simplicity and actually it is an enolization reaction. Methanesulfonic acid is used to accelerate the enolization of ketones. The reaction is carried out in the presence of CuCl2 and/or dioxygen only. In particular, it is found that the hydroxyketone formation does not require the presence of CuCl2. Matrix assisted laser desorption ionization (MALDI) and time-of-flight mass spectrometry (TOFMS) are used to record the mass spectra of α-hydroxyketones products. α-Cyano-4-hydroxycinnamic acid (CHCA) matrix promoted the molecular ion detection when 180 pmol of α-hydroxyketones is introduced into the TOFMS.
- El-Qisairi, Arab K,Qaseer, Hanan A
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- Kinetics and products of the reactions of selected diols with the OH radical
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Using a relative rate method, rate constants been measured at 296 ± 2 K for the gas-phase reactions of OH radicals with 1,2-butanediol, 2,3-butanediol, 1,3-butanediol, and 2-methyl-2,4-pentanediol, with rate constants (in units of 10-12 cm3 molecule-1 s-1) of 27.0 ± 5.6, 23.6 ± 6.3, 33.2 ± 6.8, and 27.7 ± 6.1, respectively, where the error limits include the estimated overall uncertainty of ±20% in the rate constant for the reference compound. Gas chromatographic analyses showed the formation of 1-hydroxy-2-butanone from 1,2-butanediol, 3-hydroxy-2-butanone from 2,3-butanediol, 1-hydroxy-3-butanone from 1,3-butanediol, and 4-hydroxy-4-methyl-2-pentanone from 2-methyl-2,4-pentanediol, with formation yields of 0.66 ± 0.11, 0.89 ± 0.09, 0.50 ± 0.09, and 0.47 ± 0.09, respectively, where the indicated errors are the estimated overall uncertainties. Pathways for the formation of these products are presented, together with a comparison of the measured and estimated rate constants and product yields.
- Bethel, Heidi L.,Atkinson, Roger,Arey, Janet
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p. 310 - 316
(2007/10/03)
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- Bacterial biotransformation of isoprene and related dienes
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The bacterium Pseudomonas putida ML 2 was used in the oxidative biodegradation of the acyclic dienes isoprene, trans-piperylene, cis-piperylene, and 1,3-butadiene. Regioselective dioxygenase-catalyzed dihydroxylation of alkenes yielded vicinal diols in the preferred sequence monosubstituted 〉 cis-disubstituted 〉 gem-disubstituted 〉 trans-disubstituted. The isolated diol metabolites had an excess of the R configuration (9-97% ee), and further diol oxidation was controlled by addition of propylene glycol as an inhibitor. Stereoselectivity using the ML2 strain resulted from both enzymatic asymmetric alkene dihydroxylation and kinetic resolution of diols. Enantioselective oxidation of the allylic secondary alcohol group of R configuration yielded the corresponding unsaturated ketoalcohol; the residual diol was recovered with a large excess (≥ 93% ee) of the S configuration. In addition to the enzymatic diene oxidation steps yielding unsaturated diols and ketoalcohols, evidence was also found of enzymatic alkene hydrogenation to yield saturated ketoalcohols and diols.
- Boyd, Derek R.,Clarke, David,Cleij, Marcel C.,Hamilton, John T.G.,Sheldrake, Gary N.
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p. 673 - 685
(2007/10/03)
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- Product distributions from the OH radical-induced oxidation of but-1-ene, methyl-substituted but-1-enes and isoprene in NO(x)-free air
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Product distributions resulting from the OH-induced oxidation of but-1-ene, 2-methylbut-1-ene, 3-methylbut-1-ene and isoprene in air were measured in the absence of nitrogen oxides and compared with predictions based on currently accepted oxidation mechanisms. In the case of butenes, the observed distributions of carbonyl compounds, hydroxyketones, hydroxyalkanals and diols were evaluated to obtain probabilities for the initial attack of OH radical on the outer position of the double bond (y = 0.90 ± 0.03 for 2-Me-but-1-ene and y = 0.76 ± 0.05 for both but-1-ene and 3-Me-but-1-ene), for the probability of formation of stable products in the self-reaction of secondary β-hydroxyperoxyl radicals (k(ssb)/k(ss) = 0.29 ± 0.07 for but-1-ene and k(ssb)/k(ss) = 0.19 ± 0.06 for 3-Me-but-1-ene), and for the ratio of the reaction with oxygen vs. decomposition of β-hydroxyalkoxyl radicals, k3[O2]/(k4 + k3[O2]) = 0.25 ± 0.04 for but-1-ene and = 0.38 ± 0.04 for 3-Me-but-1-ene. The last two values disagree with other published data, which suggest a smaller effect of oxygen. The oxidation of isoprene produced methacrolein and methyl vinyl ketone with a ratio 0.93 ± 0.10, the ratio of methyl vinyl ketone and 3-methylfuran was 7.3 ± 1.0. Other products were 1-hydroxy-3-methylbut-3-en-2-one (identified by mass spectrometry) and 3-methyl-3-oxo-butane (tentatively identified). The overall product distribution was complex and could not be fully elucidated. Computer simulations based on several mechanisms applied the relative probabilities for OH addition found for the but-1-enes. Comparison with the experimental data suggests probabilities for OH addition to the methylated double bond of 0.504 ± 0.027 (outer position) and 0.056 ± 0.003 (inner position), and to the non-methylated double bond of 0.335 ± 0.023 (outer position) and 0.105 ± 0.008 (inner position).
- Benkelberg,Boge,Seuwen,Warneck
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p. 4029 - 4039
(2007/10/03)
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- Controlled formation of olefin oligomers
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An oligomer is made by contacting a straight-chain, α-olefinic monomer with boron trifluoride and a hydroxy carbonyl promoter. The hydroxy carbonyl is preferably a β-hydroxy-ketone, such as 4-hydroxy-4-methyl-2-pentanone. A second promoter can be used in conjunction with the boron trifluoride and the hydroxy carbonyl promoter. Possible secondary promoters include aldehydes, alcohols, alcohol alkoxylates, carboxylic acids, ethers, ketones, and their mixtures. Preferably the oligomer product has a kinematic viscosity at 100° C. of less than 1.7 cSt; has a dimer to trimer and higher oligomer ratio of at least 1:1; and is at least 90 wt. % dimer and trimer of the monomer.
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- Selectivity in catalytic diol electrooxidation using a polypyridine ru(iv) complex
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1,2-, 1,3-, and 1,4-Butanediols and phthatic alcohol were oxidized electrocatalytically using the polypyridine [(bpy)(trpy)RuO]2+ complex (1) as oxidant under different conditions: concentration of 1, pH, and temperature. By controlling the number of coulombs passed through the electrolytic cell, it was possible to obtain selective reactions. 1-Hydroxy-2-butanone,1-hydroxy-3-butanone, γ-butyrolactone, phthalide, phtalic aldehyde, and phthalic acid were the products obtained by controlled potential electrolysis from these substrates, with yields ranging from 41 to 89%.
- Navarro, Marcelo,De Giovani, Wagner F.,Romero, Jose R.
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p. 851 - 857
(2007/10/02)
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- Oxidation of Olefins by Palladium(II). 12. Product Distributions and Kinetics of the Oxidation of 3-Buten-2-ol and 2-Buten-1-ol by PdCl42- in Aqueous Solution
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The rate expression for oxidation of both allyl alcohols was determined to be rate = k2->/+>->2, an expression identical in form with that found previously for the oxidation of ethene, allyl alcohol, and other acyclic olefins, indicating similar mechanisms.Contrary to previous reports, the product distribution from 3-buten-2-ol (6) was completely different from that for 2-buten-1-ol (7), indicating that fast isomerization into an equilibrium mixture before oxidation was not occuring.A short study of the rate of isomerization using deuteriated 6 and 7 confirmed that isomerization was slow under the oxidation conditions.The distributions gave considerable information on the effects of steric and electronic factors on the modes of hydroxypalladation.While allyl alcohol gave a 3/1 preference for addition of the Pd(II) to the center carbon due to the directing influence of the hydroxyl group, 6 gave 4/1 preference for addition of Pd(II) to the end carbon.The steric effect of the methyl is thus appreciable.With 7 the double bond is internal so steric factors are not important and the directing influence of the hydroxyl will be the important effect.The ratio of Pd(II) addition next to the carbon containing the hydroxyl group to addition to the other side of the double bond is 34/1, indicating considerable directing influence of the hydroxyl.The preference for secondary over primary hydride shift is 1.25, a value which indicates almost no carbonium ion character and considerable Pd(II)-H character.Using a specifically deuterated 7, the value of the deuterium isotope effect, kH/kD, can be determined by internal competitive hydride transfer by taking into account the positional preferance for secondary hydride shift.This value of 2.2 is close to values previously determined for ethene and allyl alcohol.
- Zaw, Kyaw,Henry, Patrick M.
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p. 1842 - 1847
(2007/10/02)
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- Acid-Catalyzed Oxidation of Oxiranes with Dimethyl Sulfoxide Giving α-Hydroxy Ketones
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The reaction of various oxiranes with dimethyl sulfoxide in the presence of Molecular Sieve 4A and acid afforded the corresponding α-hydroxy ketones.The molecular sieve found to accelerate the reaction.
- Tsuji, Tadakazu
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p. 645 - 647
(2007/10/02)
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- Simple Gas Chromatographic Identification of Monosaccharides Using a Curie-Point Type Pyrolyzer
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Simple and rapid identification of monosaccharides by gas chromatography was achieved by the application of Curie-point pyrolysis.Almost all monosaccharides were distinguishable under pyrolysis conditions of 358 deg C for 3 s.Each sugar group, e.g. aldohexoses, aldopentoses, deoxysugars, uronic acids, sugar alcohols, and aminosugars, showed a characteristic pyrogram.Keywords - carbohydrate; Curie-point pyrolysis; monosaccharide; identification; gas chromatography; GC-MS; pyrolysis gas chromatography; pyrogram
- Mitsuo, Naoki,Nakayama, Nobuko,Matsumoto, Hitoshi,Satoh, Toshio
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p. 1624 - 1626
(2007/10/02)
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- Meerwein-Ponndorf-Verley-Type Reduction of Dicarbonyl Compounds to Hydroxy Carbonyl Compounds and α,β-Unsaturated Carbonyl Compounds to Allylic Alcohols Catalyzed by Zirconocene and Hafnocene Complexes
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Group IVA metallocene complexes such as bis(η5-cyclopentadienyl)zirconium dihydrides, Cp2ZrH2 (1), and hafnium dihydrides, Cp2HfH2 (8), catalyze the chemoselective reduction of polycarbonyl compounds to hydroxy carbonyl compounds.For instance, the reduction of keto aldehydes 3-ketobutanal (2g) and 2-phenyl-2-ketoethanal (2h) proceeded selectively at aldehyde group to provide the corresponding hydroxy ketones 3g and 3h in 91percent and 93percent yields, respectively.Under similar conditions, however, cyclohexanediones were easily aromatized to benzenediols.On the other hand, 1 and 8 also catalyze the selective 1,2-reduction of various types of α,β-unsaturated carbonyl compounds, giving the corresponding allylic alcohols in good to excellent yields.Thus, steroidal dicarbonyl compounds, having an enone framework in their molecules Δ4-androstene-3,17-dione (11a) and Δ4-progestene-3,20-dione (11b) were reduced by 1 to 17-hydroxy-Δ4-androsten-3-one (12a) and 20-hydroxy-Δ4-progest-3-one (12b), which are essential human hormones, in 80percent and 67percent yields, respectively.
- Nakano, Tatsuya,Umano, Shigetoshi,Kino, Yoshio,Ishii, Yasutaka,Ogawa, Masaya
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p. 3752 - 3757
(2007/10/02)
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- Preparation of Optically Active 1,2-Diols and α-Hydroxy Ketones Using Glycerol Dehydrogenase as Catalyst: Limits to Enzyme-Catalyzed Synthesis due to Noncompetitive and Mixed Inhibition by Product
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Glycerol dehydrogenase (GDH, EC 1.1.1.6, from Enterobacter aerogenes or Cellulomonas sp.) catalyzes the interconversion of analogues of glycerol and dihydroxyacetone.Its substrate specificity is quite different from than of horse liver alcohol dehydrogenase (HLADH), yeast alcohol dehydrogenase, and other alcohol dehydrogenases used in enzyme-catalyzed organic synthesis and is thus a useful new enzymic catalyst for the synthesis of enantiomerically enriched and isotopically labeled organic molecules.This paper illustrates synthetic applications of GDH as a reduction catalyst by the enantioselective reduction of 1-hydroxy-2-propanone and 1-hydroxy-2-butanone to the corresponding R 1,2-diols (ee = 95-98percent). (R)-1,2-Butanediol-2-d1 was prepared by using formate-d1 as the ultimate reducing agent.Comparison of (R)-1,2-butanediol prepared by reduction of 1-hydroxy-2-butanone enzymatically and with actively fermenting bakers' yeast indicated than yield and enantiomeric purity were similar by the two procedures.Reactions proceeding in the direction of substrate oxidation usually suffer from slow rates and incomplete conversions due to product inhibition.The kinetic consequences of product inhibition (competitive, noncompetitive, and mixed) for practical synthetic applications of GDH, HLADH, and other oxidoreductases are analyzed.In general, product inhibition seems the most serious limitation to the use of these enzymes as oxidation catalysts in organic synthesis.
- Lee, Linda G.,Whitesides, George M.
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- Selective Cross-Acyloin Condensation Catalyzed by Thiazolium Salt. Formation of 1-Hydroxy 2-Ones from Formaldehyde and Other Aldehydes
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The condensation of formaldehyde with another aldehyde catalyzed by 3-ethylbenzothiazolium bromide in the presence of triethylamine gives selectively 1-hydroxy 2-ones.This selective cross-acyloin condensation indicates an inverse selectivity in the reactions of the conjugate base of thiazolium salt 17 and of the carbanion bound to thiazolium ring 19 toward aldehyde.
- Matsumoto, Toshihiko,Ohishi, Masafumi,Inoue, Shohei
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p. 603 - 606
(2007/10/02)
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- Formation of Thioamide Derivatives from Reactions of Isothiocyanates with Oxazol-2-amines
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4-Substituted oxazol-2-amines react with isothiocyanates to give products having a thioamide function at C5.The reaction is considered to be an electrophilic process in competition with the usual reaction of the amino group with the isothiocyanate.The nature of the isothiocyanate and the type of substituent at C4 affect the amount of the thioamide product formed.Some chemical properties of the thioamides are also investigated.
- Crank, George,Khan, Humaid R.
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p. 447 - 458
(2007/10/02)
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