Spectrophotometric Determination of Methoxyl

Mathers, Alex P; Pro, Maynard J

doi:10.1021/ac60106a053

Cited by 22 publications

(8 citation statements)

References 13 publications

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“…The methoxyl contents were determined by a modification of the method of Mathers and Pro (1955). Lignin (0.15 g) was heated with concentrated sulfuric acid (96%, 10 ml), under reflux, for 10 minutes.The reaction mixture was cooled, and water (70 ml) was added through the condenser.…”

Section: Elemental Analysismentioning

confidence: 99%

Solvent Effects on Organosolv Lignin fromPinus caribaea hondurensis

Balogh¹,

Curvelo²,

Groote³

1992

Holzforschung

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Keywords Lignin analysis Organosolv lignin Molccular wcight (Mini, Mw and MWD) dctcrminations Hilücbrand's solubility paramctcr Sawdust Pinus caribaea hondurensis SummaryLignin from Pinus caribaea hondurensis sawdust (pre-extracted with bcnzenc/mcthanol 1:1) was obtaincd by pulping using ninc diffcrent organic solvcnts (in 9:1 mixturcs with 2.0 N HC1 aqucous Solutions) in a stainlcss stcel rcactor at 125 °C for six hours.Thc obtaincd lignins wcrc charactcrizcd by chcmical analysis (clcmcntal analysis, mcthoxyl and phcnolic hydroxyl groups) and by infrarcd spcctroscopy. Morcovcr, the avcrage molccular wcights (Mn, Mw and MWD) werc dctcrmincd by vapor phasc osmomctry and high pcrformancc-size exclusion chromatography and shown thrcc diffcrent pattcrns according to thc solvent mixturcs cmploycd. The yields of lignin dcpcnd on the acccssibility and nuclcophilicity of thc solvcnts äs well äs on thc lignin solubility, and are rclatcd to thc Hildcbrand's solubility paramctcrs ( ) of the solvent mixturcs. The plot of lignin yields against 6 show a charactcristic "Bell shapc" curvc wilh maximum at 23 MPa l/2 corrcsponding to thc lignin solubility paramctcr. IntroductionPulping processes can be divided into three main groups, depending on the solvent System employed: -Aqueous processes: These pulping processes use water äs solvent and inorganic reagents to cleave the protolignin to water soluble fragments. The inorganic reagents are generally used in high concentrations and the processes are carried out at high temperatures and pressures. -Organosolv processes: These processes use organic solvents, commonly in association with water and, in the most cases, an acid catalyst. In the acid catalyzed organosolv processes, water acts äs nucleophilic agent and reacts with reactive centers (which have been activated by the catalyst) in the protolignin. Organosolv processes generally use lower temperatures and pressures than the aqueous processes, and differ from in the recovery of the Chemicals, in organosolv processes only the solvent has to be recovered. -Mixed processes: The solubilization power of the organic solvents can be used in association with water and inorganic reagents producing mixed processes. These Systems are also performed at high temperatures and pressures and the inorganic reagents have to be recovered due to economical reasons. Organosolv processes making use of alkaline reagents are included in this group.

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Section: Elemental Analysismentioning

confidence: 99%

Solvent Effects on Organosolv Lignin fromPinus caribaea hondurensis

Balogh¹,

Curvelo²,

Groote³

1992

Holzforschung

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“…Chromogen determinations on the fresh feces were carried out by the method of Reid et al (9); the other determinations were carried out on oven-dried samples. The methoxyl determination was carried out by the method of Mathers and Pro (7), as modified by Shearer (79).…”

Section: Methodsmentioning

confidence: 99%

Forage Digestibility, Benzene-Ethanol Extracts of Forage and Feces as Indicators of Digestibility

Shearer¹

1963

J. Agric. Food Chem.

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the above findings, although neither amino acid alone resulted in improved growth. The addition of both, however, improved growth, feed efficiency, and protein efficiency. This suggests that both are limiting to about an equal degree. Even with the addition of these two amino acids, however, or with the addition of seven amino acids, the growth was only 88% of that obtained with skim milk. There are, apparently, other limiting amino acids besides methionine and threonine, a situation which could be due either to a lack in availability or to the fact that the amounts of threonine and methionine added were not adequate for maximum improvement in growth.To obtain a maximum response to an amino acid addition, it is necessary to add the optimum amount of the most limiting amino acids (22).

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“…The colorimetric reaction is then carried out in accordance with the details given by Mathers and Pro (7). One or more 0.2-1-ml samples are taken and transferred into a n equal number of 25-ml graduated flasks.…”

Section: Experimental]mentioning

confidence: 99%