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  • 1
    Electronic Resource
    Electronic Resource
    Reactions of p-Hydroxybenzyl Alcohol Derivatives and Their Methyl Ethers with Molecular Chlorine1 (1960)
    s.l. : American Chemical Society
    The @journal of organic chemistry 25 (1960), S. 715-720 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo01075a010
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  • 2
    Electronic Resource
    Electronic Resource
    Organosolv pretreatment for enzymatic hydrolysis of poplars: isolation and quantitative structural studies of lignins (1999)
    Springer
    Clean products and processes 1 (1999), S. 187-198 
    Details
    ISSN: 1436-722X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract  Lignins could become important sources of chemical feedstocks and fuels if fractionation of the polymeric constituents of lignocellulosic materials could be improved. To utilize these polymeric components, it is important to understand their composition, chemical characteristics, and properties as a function of how the separation of the polymers is conducted. This paper presents characterization of several lignins as a function of fractionation method and isolation. Organosolv lignins were isolated from pulping liquors obtained by pulping Populus tremuloides (aspen) at 165  °C for 1–2.5 h with methanol: water (70 : 30 by volume). Pulping catalysts were various concentrations of mineral acids (H2SO4 or H3PO4) or salts (NaHSO4). Lignins were isolated by: (1) precipitation through the addition of water of the major lignin fraction (water–insoluble lignin) and (2) solubilization in acetone to yield a small fraction of acetone-soluble lignin. The characterization of these materials was performed through extensive quantitative 13C-NMR and by use of the Distortionless Enhancement by Polarization Transfer (DEPT) NMR sequence to assess the major types of structures formed under these conditions. In addition infra-red spectral data obtained using the DRIFT technique were employed to investigate a few of the structural characteristics. Simple functional groups were also analyzed by chemical methods for comparison. Correlation of differences in the structures of the organosolv lignins was made with the severities of the organosolv pretreatments which were expressed in terms of combined severity factors that incorporated time, temperature, and catalyst effects (pH of the pulping liquor). At low severity, the alkyl aryl ether bonds, the predominant bonds in native lignin, were hydrolyzed leading to materials with low ether bond content, high phenolic hydroxyl content, some methanol incorporation at the side chain, and a small amount of carbon-carbon condensed structures. Quantitation of minor structures such as syringaresinol and p-hydroxybenzoate is given, and the key types of structures present. As the severity increases, a higher extent of carbon-carbon condensation and side-chain degradation was observed while the ether bonding content was decreased. These lignins have low apparent weight-average molecular weights and low polydispersities. The lignins isolated from high severity organosolv pretreatments were completely different from native lignins. The degree of side chain degradation was high, and the number of carbons conventionally employed to describe a lignin repeating unit was substantially decreased from nine to eight or less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100980050027
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Diffusion of dissolved oxygen in liquid-saturated Douglas fir sapwood (1977)
    Springer
    Wood science and technology 11 (1977), S. 225-236 
    Details
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary A technique was developed for the determination of the effective dissolved oxygen diffusivity in liquid-saturated softwood in a diffusion cell under ambient pressure. From the measurements in the temperature range 2° to 50°C, the activation energy of diffusion was found to be 4.6 kcal/mole. The diffusivity in summerwood is about one half of that in springwood. The diffusivity of dissolved oxygen through composite springwood and summerwood layers was based upon samples of two Douglas fir sapwood blocks saturated with water. In the radial and tangential directions, diffusivity was 1.4 to 2.3x10-6cm2/s, which is about 6 to 10% that of dissolved oxygen diffusivity in water. The diffusivity in the longitudinal direction is about 5.5 times that in the other two directions. The diffusivity of dissolved oxygen through liquor-saturated wood and the effect of delignification on oxygen diffusion were also determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365617
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of pH on the autoxidation kinetics of vanillin (1983)
    Springer
    Wood science and technology 17 (1983), S. 107-116 
    Details
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The autoxidation kinetics of vanillin (4-hydroxy-3-methoxy benzaldehyde) have been investigated in aqueous media between pH 5.0 and 13.5. The results obtained clearly show two distinct reaction mechanisms are operative. At pH 7.3 the reaction orders with respect to vanillin concentration and oxygen partial pressure are 1.50 and 0.5 respectively, indicative of a free-radical chain process. A bimolecular ionic pathway is indicated at pH 11.0 and above since the reaction orders with respect to both vanillin and oxygen are 1.00. The formation of a hydroperoxide intermediate is believed to be the first step in both pathways. The energy of activation was found to be 14.2 kcal/mole at pH 7.3 and 13.6 kcal/mole at pH 11.0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369128
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  • 5
    Electronic Resource
    Electronic Resource
    Ammonium sulfide organosolv pulping (1983)
    Springer
    Wood science and technology 17 (1983), S. 217-226 
    Details
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The use of ammonium sulfide in aqueous ethanol and methanol was investigated for pulping of wood. Hemlock chips required 21% ammonium sulfide (equivalent to 19% Na2O) at 180°C to become delignified to the kappa range 35–50. The yields exceeded those of conventional kraft pulps by 14% on dry wood basis. Over 75% of the original glucomannan was recovered in the pulp as the consequence of end group stabilization by ammonium sulfide. The intrinsic viscosity of the pulps, measured in cadoxen was 10.65 dl/g — approximately double the value for softwood kraft pulps. The pulps were readily bleached and possessed higher tensile and burst strengths but lower tear strengths than kraft pulps. Ammonium sulfide pulps from cottonwood were likewise obtained in high yields and with adequate strength properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372320
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetic study on the alkaline degradation of cotton hydrocelluloseProd. No. 1485 (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 587-600 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of alkaline degradation of cotton hydrocellulose were determined in 5% NaOH at various temperatures. An activation energy of 24 kcal./mole was found for the endwise degradation reaction, while that of termination to a stable m-saccharinic acid endunit is 32 kcal./mole. Consequently, the DPn of the degradable chain length is highly dependent on the reaction temperature, being 1000 at 65°C. and 140 at 132°C. At lower temperatures, the majority of degrading chains terminate to a normal reducing endgroup at the crystalline-amorphous transition region. From the data, the DPn of cellulose chain segments participating in the amorphous regions of the original cotton fibril was calculated to be 143. This result strongly supports the classical micellar fibril structure over the folded model proposed by Manley.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070110408
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Organosolv pretreatment for enzymatic hydrolysis of poplars: I. Enzyme hydrolysis of cellulosic residues (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 643-649 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aspen (Populus tremuloides) and black cottonwood (Populus trichocarpa) organosolv pulps produced in a wide range of solvent composition (between 30 and 70% by volume of methanol) and catalysts (H2SO4 and H3PO4) such that the cooking liquor pH ≤ 3 are easily digested by enzymes. The total yields of hydrolysis residues (pulps) are in the 40-60% range; the acid-catalyzed delignification followed by enzyme hydrolysis can generate 70-88% of the original six-carbon sugars contained in the wood. Glucomannan and arablnogalactan are dissolved into the pulping liquor in the pH range of 2-4.5. Lower pH (≤3) leads to additional solubilization of six-carbon sugars. These sugars may be fermented directly. From the insoluble hydrolysis residues, 36-41% conversions of wood into fermentable sugars were obtained after enzyme hydrolysis; the starting feedstocks contain 50.8 and 46.6% hexosans, respectively, for aspen and black cotton-wood. The kinetics of enzymatic hydrolysis of cellulose can be formally treated as two simultaneous pseudo-first-order reactions in which fast and slow hydrolyses of cellulose occur. Correlations between the glucan digestibility and the effect of the pretreatment have been made. The higher residual xylan content reduces the amount of the rapidly hydrolyzable glucan fraction and lowers the glucan digestibility. The proposed simple kinetic treatment is very helpful in assessing the effect of the pretreatment on pulp enzyme hydrolyzability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260310703
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  • 8
    Electronic Resource
    Electronic Resource
    Evaluation of organosolv pulp as a suitable substrate for rapid enzymatic hydrolysis (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 609-612 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: NO Abstract.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260250225
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    Paper (German National Licenses)
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