Analysis of positions of substitution of O-methyl or O-ethyl groups in partially methylated or ethylated cellulose by the reductive-cleavage method

D’Ambra, Anello J.; Rice, Michael J.; Zeller, Samuel G.; Gruber, Patrick; Gray, Gary R.

doi:10.1016/0008-6215(88)85046-8

Cited by 47 publications

(7 citation statements)

References 12 publications

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“…High ethylated and hydrophobic areas could be less accessible to hydrolysis, resulting in a methyl DS Me value too high. Therefore, two further reference methods were applied: a) GLC of methyl glucosides obtained by methanolysis and silylation (Gonera et al 2002), and b) GLC of 4-O-triethylsilyl-1,5-anhydro-2,3,6-tri-O-(m)ethyl alditols obtained by reductive cleavage (D'Ambra et al 1988;Jun and Gray 1987;Rolf and Gray 1982). Both methods eliminate the reactive aldehyde function by glycosidation (a) or by reduction (b).…”

Section: Evaluation Of the Methodsmentioning

confidence: 99%

Critical re-investigation of the alditol acetate method for analysis of substituent distribution in methyl cellulose

Voiges

Adden

Rinken³

et al. 2012

Cellulose

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The alditol acetate method is a common procedure for sugar analysis, also applied to determine the substituent distribution in monomer units of polysaccharide ethers like methyl cellulose by gas liquid chromatography. Consisting of several preparation and work-up steps this procedure is both time consuming and prone to side reactions that promote discrimination of single constituents, especially when no peralkylation step is performed prior to hydrolysis. As a consequence results scatter in dependence on individual treatment and conditions. In the context of this work these critical points were overcome by strict but simplified work-up procedures and using acid instead of alkaline catalyzed acetylation. Under the acidic conditions the tedious removal of borate is no longer necessary and a reduced time requirement was achieved as well as good reproducibility. Comparison with independent reference methods excluded a systematic error of the method and confirmed the results obtained. Without peralkylation, i.e. in the presence of free hydroxyl groups, another fast modification of the method using DMSO as solvent, no removal of borate, and 1-methylimidazole as catalyst for acetylation was found to produce a systematic error.

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Section: Evaluation Of the Methodsmentioning

confidence: 99%

Critical re-investigation of the alditol acetate method for analysis of substituent distribution in methyl cellulose

Voiges

Adden

Rinken³

et al. 2012

Cellulose

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“…Structural analysis of EPS by methylation analysis and reductive cleavage. The native and enzyme-treated EPS preparations of P. digitatum were permethylated by a modified Hakomori procedure, using lithium dimethyl sulfinyl anion and methyliodide in dimethyl sulfoxide (7). The permethylated EPS was isolated by extraction with dichloromethane and purified on an LH-20 column.…”

Section: Methodsmentioning

confidence: 99%

New structural features of the antigenic extracellular polysaccharides of Penicillium and Aspergillus species revealed with exo-beta-D-galactofuranosidase

et al. 1992

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To study the structures of the epitopes of the extracellular polysaccharides from Penicilium and Aspergillus species, an exo-13-D-galactofuranosidase was purified from a commercial crude enzyme preparation from Trichoderma harzianum. Analysis of ring size and linkage position of the galactose residues of the extracellular polysaccharide of Penicillium digitatum, before and after enzymatic treatment, was determined by the reductive-cleavage technique. In addition to terminal and 13(1-5)-linked galactofuranosides, P(1-6)-linked and P(1,5,6)-linked branched galactofuranose residues could be identified. After degradation with the purified exo-13-D-galactofuranosidase, all initial linkages of the galactofuranose residues were still present, but the amount of D(1-5)-linked galactofuranose residues had decreased considerably. Treatment of the extracellular polysaccharides ofPenicillium and Aspergils species with the purified exo-o-D-galactofuranosidase resulted in complete disappearance of the enzyme-linked immunosorbent assay reactivity of these polysaccharides, using immunoglobulin G antibodies raised against P. digitatum. Therefore, with the use of this enzyme, it was proved that the 13(1-5)-linked galactofuranosyl residues only are responsible for the antigenicity of the extracellular polysaccharides ofPenicillium and Aspergills molds. A new structural model for the antigenic galactofuranose side chains of the galactomannan from P. digitatum is proposed. Molds are able to excrete a large variety of polysaccharides, some of them with antigenic properties (22, 29). Several authors studied the chemical structure of polysaccharides isolated from mycelium of mold species belonging to the genera Penicillium and Aspergillus (3-5). Penicillium and Aspergillus species are important fungi which are distributed worldwide and are the cause of many cases of food spoilage. Medically, some members are significant because of their ability to cause aspergillosis in humans and the release of mycotoxins. The polysaccharides are constituted mainly of mannose, galactose, and glucose, with minor amounts of protein (3-5). Galactosamine has been found in the polysaccharides of several Aspergillus species (2, 13, 27). Extracellular polysaccharides (EPSs) produced by these molds appeared to have similar structures (12, 24).

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“…The solvent, the type of alkylation agent, the type of auxiliary base, reaction temperature, and dissolution state are parameters that can be-and have been-varied. The most common alkylation agent in the lab is methyl iodide (Ciucanu and Kerek 1984;Needs and Selvendran 1993;Hakamori 1964;D'Ambra et al 1988;Klemm and Stein 1995)-in contrast to the industrially used methyl chloride-but also less common reagents, such as methyl triflate, were used (Mischnick 1991). Solvents are DMSO, DMAc/LiCl, DMF, THF, or water, the type of solvent also determining the types of base that can be used.…”

Section: Introductionmentioning

confidence: 99%

Solid-state NMR studies of methyl celluloses. Part 1: regioselectively substituted celluloses as standards for establishing an NMR data basis

et al. 2008

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Three methyl celluloses with completely uniform substitution pattern, 2-O-methyl cellulose (1), 3-O-methyl cellulose (2) and 6-O-methyl cellulose (3), were prepared according to the cationic ring opening polymerization approaches starting from substituted 1,2,4-orthopivalate derivatives of D-glucose. These samples allowed for the first time to sort out the methyl substitution effects on solid-state NMR chemical shifts and relaxation. Dipolar dephasing experiments allowed the detection and assignment ( 1 H, 13 C) of the methyl groups. In 1 and 2, these resonances overlapped with those of C-6, whereas in 3, the methyl signal experienced a low-field shift into the region of C-2,3,5. 13 C T 1 experiments were used to verify different relaxation behavior of the carbon sites, particularly the short relaxation time of at the carbon substitution site next to the methyl groups. This effect was used to unambiguously identify the 13 C chemical shifts of the carbons carrying the methoxyl substituent, although they overlap with all resonances in the C-2,3,5 region. The data obtained for the standard samples with uniform substitution will now be used as the basis for determining methylation patterns and substitution degree in commercial methyl celluloses.

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Analysis of positions of substitution of O-methyl or O-ethyl groups in partially methylated or ethylated cellulose by the reductive-cleavage method

Cited by 47 publications

References 12 publications

Critical re-investigation of the alditol acetate method for analysis of substituent distribution in methyl cellulose

Critical re-investigation of the alditol acetate method for analysis of substituent distribution in methyl cellulose

New structural features of the antigenic extracellular polysaccharides of Penicillium and Aspergillus species revealed with exo-beta-D-galactofuranosidase

Solid-state NMR studies of methyl celluloses. Part 1: regioselectively substituted celluloses as standards for establishing an NMR data basis

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