Alkaline Degradation of Mannan

Niemelä, Klaus; Sjöström, Eero

doi:10.1515/hfsg.1986.40.1.9

Cited by 16 publications

(9 citation statements)

References 11 publications

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“…also been used to identify the compounds that were adsorbed onto aluminium 591 hydroxide from a Bayer liquor [38], to identify the components of water-soluble extracts of plant remains in bauxites [42] and to identify the products of alkaline leaching of plant materials related to bauxite digestion [6]. GC-MS has been used extensively by Niemela and co-workers in studies related to the digestion of a range of natural materials, including woods and bark, cellulose, starch and humic materials [66][67][68][69][70][71][72][73][74].…”

Section: High Performance Liquid Chromatography (Hplc)mentioning

confidence: 99%

A review of the determination of organic compounds in Bayer process liquors

Power

Loh

Wajon³

et al. 2011

Analytica Chimica Acta

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Bayer process liquors present a difficult and complex matrix to the analytical chemist, and the history of the application of modern analytical techniques to this problem is a case study in innovation. All Bayer process liquors contain organic compounds, in amounts varying from traces to several grams per litre. The total organic carbon content of Bayer liquors may be less than 5 g/L up to as much as 40 g/L. The presence of these organic impurities is of concern to Bayer technologists because they can have significant impacts on the economics of the process and the quality of the product. This review examines the history and current state-of-the-art of the analysis of organics in Bayer process liquors, and provides guidance on the applicable techniques matched to a comprehensive list of the compounds most likely to be present.

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Section: High Performance Liquid Chromatography (Hplc)mentioning

confidence: 99%

A review of the determination of organic compounds in Bayer process liquors

Power

Loh

Wajon³

et al. 2011

Analytica Chimica Acta

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“…Applying a ratio of 1.0 mole SMCA/mole AXU, a DS NMR of 0.39 (11) was realized. At a molar ratio of 1.0:1.5:1.5 (AXU:SMCA:NaOH), the DS decreases to 0.23 (12). Most of SMCA does not dissolve in the reaction mixture used to synthesize 12.…”

Section: Methodsmentioning

confidence: 99%

“…[10,11] The distribution of the substituents in the AXU of commercial carboxymethyl cellulose (CMC) samples from birch Kraft pulp with a content of about 20% CMX was studied by Niemelä and Sjö strö m by gas-liquid chromatography and mass spectrometry. [12] Details about the reactivity of xylan regarding the carboxymethylation under different conditions and information about structure-property-relationship are still missing.…”

Section: Introductionmentioning

confidence: 99%

Carboxymethyl Xylan ‐ Control of Properties by Synthesis

Petzold

Schwikal

Günther

et al. 2005

Macromolecular Symposia

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Summary:The hemicellulose xylan is a polysaccharide that occurs in nature in enormous amount in various one year-and perennial plants having different structures and molecular masses. Versatile ways to generate bio-based functional polymers result from the chemical modification of this biopolymer. In our research, xylans from various resources like birch-, beech-, and eucalyptus wood and from oat husk, rye bran, and corn cob were used to investigate the important method of carboxymethylation in detail. Different activation procedures were elaborated to synthesize carboxymethyl xylan. One step reactions lead to products with a degree of substitution (DS) from 0.13 to 1.22 in dependence on the molar ratio of anhydroxylose unit (AXU) to reagent. Two step syntheses yielded DS values up to 1.65. Carboxymethyl xylans are water soluble at a DS of 0.3. The solutions have different clearness depending on the provenience. NMR spectroscopy and HPL chromatography were applied to characterize the carboxymethyl xylans in detail.

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“…54 On-purpose synthesis routes were not reported. DHAA has often been detected during alkaline degradation of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 13 sugar polymers [55][56][57][58][59][60][61][62][63] and humic acids, 64 and in contrast with the other compounds, synthesis routes for DHAA have been reported, as it serves as an intermediate in the production of muscarine 65 or muconic acid. 66 DHAA may thus also be considered as a potential precursor of muconic acid, which in turn is a potential precursor for adipic acid or terepthalic acid, monomers for nylon and polyethylene terephthalate, respectively.…”

Section: Synthesis Of New Diester and Diacid Building Blocks Through mentioning

confidence: 99%

Synthesis of Novel Renewable Polyesters and Polyamides with Olefin Metathesis

Dewaele¹,

Meerten²,

Verbelen³

et al. 2016

ACS Sustainable Chem. Eng.

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Unsaturated and hydroxyl-functionalized C6-dicarboxylic acids were successfully synthesized via olefin metathesis from methyl vinyl glycolate (MVG), a renewable α-hydroxy C4-ester product from Lewisacid carbohydrate conversion. Addition of a second-generation Hoveyda-Grubbs catalyst to neat MVG leads to a near quantitative yield of dimethyl-2,5-dihydroxy-3-hexenedioate (DMDHHD). Additional hydrolysis and hydrogenation steps form interesting polymer building blocks like 2,5-dihydroxy-3hexenedioic acid (DHHDA) and 2,5-dihydroxyadipic acid (DHAA). Their use in polyester and polyamide synthesis is demonstrated after determination of their physical and spectroscopic characteristics. Copolymerization of DHHDA with L-lactic acid for instance produces a crosslinked poly(L-lactic acid-co-DHHDA) polyester. Proof of crosslinks is ascertained by NMR and FT-IR. Substantial impact on the melting, thermal and polar properties of PLA are observed already at low amounts of DHHDA (0.1 mol%) in accord with the presence of crosslinks in the polymer. Bio-based polyamides were also synthesized by equimolar reaction of DHHDA with hexamethylenediamine, producing a renewable polyamide analogue of the petroleum-based nylon 6,6. Interestingly, the assynthesized polyamide (α-bishydroxylated unsaturated polyamide, HUPA) possesses similar thermal stability as nylon 6,6 but shows different chemical properties as a result of the double bond and αhydroxy functionality.

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Alkaline Degradation of Mannan

Cited by 16 publications

References 11 publications

A review of the determination of organic compounds in Bayer process liquors

A review of the determination of organic compounds in Bayer process liquors

Carboxymethyl Xylan ‐ Control of Properties by Synthesis

Synthesis of Novel Renewable Polyesters and Polyamides with Olefin Metathesis

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