CHOLLA GUM: I. STRUCTURE OF THE DEGRADED CHOLLA GUM

1966 ◽  
Vol 44 (3) ◽  
pp. 327-333 ◽  
Author(s):  
V. M. Parikh ◽  
J. K. N. Jones
Keyword(s):  
Chain Length ◽  
Galacturonic Acid ◽  
Uronic Acid ◽  
Partial Hydrolysis ◽  
Average Chain Length ◽  
Hydrolysis Of

Purified cholla gum (Opuntiafulgida) contains L-arabinose (51.6%), D-galactose (31.7%), D-xylose (15.0%), L-rhamnose (2-3%), and D-galacturonic acid (11.2%). Partial hydrolysis of the gum by cold acid produced a polymer which contained only D-galactose and D-galacturonic acid in the proportion 9:2. Methylation and hydrolysis of the degraded gum produced 2,3,4,6-tetra-O-methyl-D-galactose (2 moles), 2,3,4-tri-O-methyl-D-galactose (1 mole), 2,4,6-tri-O-methyl-D-galactose (2 moles), 2,4-di-O-methyl-D-galactose (4 moles), and 2,3,4-tri-O-methyl-D-galacturonic acid (2 moles). Smith-type degradation of the degraded gum produced D-galactose (6 moles), glycolaldehyde (? moles), glycerol (2.5 moles), and glyceronic acid (2.5 moles).Hydrolysis of the undegraded gum produced an aldobiouronic acid, which was proved to be 3-O-(β-D-galactopyranosyl uronic acid)-D-galactose by its reduction, methylation, and the identification of the methylated sugars obtained by the hydrolysis of the octamethyl galactobioside.Based on these results, a possible structure for the average chain length of the degraded gum has been proposed.

THE CONSTITUTION OF A METHYL GLUCURONOXYLAN FROM KAPOK (CEIBA PENTANDRA)

1959 ◽  
Vol 37 (5) ◽  
pp. 922-929 ◽  
Author(s):  
A. L. Currie ◽  
T. E. Timell
Keyword(s):  
Galacturonic Acid ◽  
Uronic Acid ◽  
Glucuronic Acid ◽  
Molar Ratio ◽  
Side Chain ◽  
Partial Hydrolysis ◽  
Alkaline Extraction ◽  
Branching Points ◽  
Seed Hairs ◽  
Hydrolysis Of

The seed hairs of kapok (Ceibapentandra) on alkaline extraction have yielded a hemicellulose composed of xylose and uronic acid residues. Partial hydrolysis of the polysaccharide gave 2-O-(4-O-methyl-α-D-glucopyranosyluronic acid)-D-xylopyranose, 4-O-methyl-D-glucuronic acid, and, probably, galacturonic acid. Hydrolysis of the fully methylated hemicellulose yielded a mixture of 2-O- and 3-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and 2-O-(2,3,4-tri-O-methyl-α-D-glucopyranosyluronic acid)-3-O-methyl-D-xylopyranose in a molar ratio of 1.1:38:1:6. The number-average D.P. of the native and the methylated polysaccharides was 177 and 124, respectively. On the basis of this and other evidence it is suggested that the average hemicellulose molecule contains approximately 180 1,4-linked β-D-xylopyranose residues, one eighth of which carry a single terminal side chain of 4-O-methyl-D-glucuronic acid, attached through an α-glycosidic bond to C2 of the xylose. The xylan framework contains, on the average, slightly less than two branching points per macromolecule, most of them probably originating from C3. The number of acid side chains and branches is twice as large as that of the otherwise similar 4-O-methyl glucuronoxylan present in the seed hairs of milkweed floss.

THE CONSTITUTION OF A HEMICELLULOSE FROM SUGAR MAPLE (ACER SACCHARUM)

1959 ◽  
Vol 37 (5) ◽  
pp. 893-898 ◽  
Author(s):  
T. E. Timell
Keyword(s):  
Acer Saccharum ◽  
Galacturonic Acid ◽  
Sugar Maple ◽  
Glucuronic Acid ◽  
Linear Chain ◽  
European Beech ◽  
Partial Hydrolysis ◽  
White Birch ◽  
Yellow Birch ◽  
Hydrolysis Of

Partial hydrolysis of the main hemicellulose constituent of sugar maple (Acersaccharum) has yielded D-xylose, D-galacturonic acid, 4-O-methyl-D-glucuronic acid, and 2-O-(4-O-methyl-α-D-glucosyluronic acid)-D-xylose. Hydrolysis of the fully methylated polysaccharide gave a mixture of 2-O- and 3-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and 2-O-(2,3,4-tri-O-methyl-α-D-glucosyluronic acid)-3-O-methyl-D-xylose in a mole ratio of 3:111:1:12. The number-average degrees of polymerization of the native and the methylated polysaccharide were 205 and 149, respectively. These data indicate that the hemicellulose is composed of a linear chain of 1,4-linked β-D-xylose residues and that on the average every tenth residue of the chain carries a terminal 4-O-methyl-D-glucuronic acid residue attached through its C2. The structure of the polysaccharide is similar to that of the main hemicellulose component of European beech, white birch, and yellow birch.

Structure of the Capsular Polysaccharide of Klebsiella K-type 56

1973 ◽  
Vol 51 (18) ◽  
pp. 3021-3026 ◽  
Author(s):  
Yuen-Min Choy ◽  
Guy G. S. Dutton
Keyword(s):  
Uronic Acid ◽  
Capsular Polysaccharide ◽  
Periodate Oxidation ◽  
Side Chain ◽  
Partial Hydrolysis ◽  
Hydrolysis Of

Methylation, periodate oxidation, and partial hydrolysis studies on the capsular polysaccharide of Klebsiella K-type 56 show the structure to be a repeating unit consisting of[Formula: see text]The nature of the anomeric linkages was determined by p.m.r. spectroscopy of isolated oligosaccharides. The position of the L-rhamnose side chain was defined by characterization of the di- and tetrasaccharides obtained by partial hydrolysis of the fully methylated polysaccharide.This structure represents the first capsular polysaccharide lacking uronic acid to be studied in the genus Klebsiella.

GUM JEOL: THE STRUCTURE OF THE DEGRADED GUM DERIVED FROM IT

1964 ◽  
Vol 42 (1) ◽  
pp. 107-112 ◽  
Author(s):  
A. K. Bhattacharyya ◽  
C. V. N. Rao
Keyword(s):  
Acid Hydrolysis ◽  
Galacturonic Acid ◽  
Uronic Acid ◽  
Periodate Oxidation ◽  
Neutral Fraction ◽  
Partial Structure ◽  
Mild Acid Hydrolysis ◽  
Acidic Fraction ◽  
Hydrolysis Of ◽  
Mild Acid

Gum Jeol has been shown to be composed of residues of D-galactose, L-arabinose, and D-galacturonic acid. On mild acid hydrolysis the gum gave an aldobiouronic acid, viz. 3-O-(D-galactopyranosyl uronic acid)-D-galactopyranose. Hydrolysis of the fully methylated degraded gum yielded 2,3,4,6-terra-(3 moles); 2,3,4-tri-(2 moles); 2,4-di-(1 mole); and 2-O-methyl-D-galactose (1 mole) in the neutral fraction of the hydrolyzate. The reduced acidic fraction yielded 2,3,4-tri-(2 moles) and 2,4-di-O-methyl-D-galactose (2 moles). Based on these results a partial structure of the degraded gum has been proposed, the additional evidence of which was deduced from periodate oxidation studies of the degraded gum.

CONSTITUTION OF A 4-O-METHYLGLUCURONOXYLAN FROM THE WOOD OF TREMBLING ASPEN (POPULUS TREMULOIDES MICHX.)

1961 ◽  
Vol 39 (5) ◽  
pp. 1059-1066 ◽  
Author(s):  
J. K. N. Jones ◽  
C. B. Purves ◽  
T. E. Timell
Keyword(s):  
Populus Tremuloides ◽  
Galacturonic Acid ◽  
Glucuronic Acid ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Quantitative Yield ◽  
Partial Hydrolysis ◽  
Trembling Aspen ◽  
Linear Framework ◽  
Hydrolysis Of

A 4-O-methylglucuronoxylan has been isolated in almost quantitative yield from the wood of trembling aspen (Populustretmuloides Michx.) The hemicellulose was electrophoretically homogeneous and had a number-average degree of polymerization of 212. Partial hydrolysis gave D-xylose, galacturonic acid, 4-O-methylglucuronic acid, and 2-O-(4-O-methyl-α-D-glucopyranosyluronic acid)-D-xylopyranose. Methanolysis and hydrolysis of the fully methylated polysaccharide, which contained 108 xylose residues per average molecule, gave 2-O-methylxylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and methyl 2-O-(2,3,4-tri-O-methyl-α-D-glucopyranosyluronic acid) -3-O-methyl-D-xylopyranoside in a mole ratio of 0.2:95:1:11. It is concluded that the hemicellulose contained a linear framework of approximately 200 (1 → 4)-linked β-D-xylopyranose residues and that, on the average, every ninth xylose unit carried a (1 → 2)-linked 4-O-methyl-α-D-glucuronic acid residue directly attached to the xylan backbone. The polysaccharide is evidently similar to the 4-O-methylglucuron-oxylans occurring in the wood of all arborescent angiosperms so far investigated.

Organic material dissolved during oxygen-alkali pulping of hot water extracted birch sawdust

TAPPI Journal ◽  
2015 ◽  
Vol 14 (4) ◽  
pp. 237-244 ◽  
Author(s):  
JONI LEHTO ◽  
RAIMO ALÉN
Keyword(s):  
Acetic Acid ◽  
Betula Pendula ◽  
Cooking Time ◽  
Hot Water ◽  
Partial Hydrolysis ◽  
Chemical Pulping ◽  
Black Liquors ◽  
Aliphatic Carboxylic Acids ◽  
Hydrolysis Of ◽  
Cooking Conditions

Untreated and hot water-treated birch (Betula pendula) sawdust were cooked by the oxygen-alkali method under the same cooking conditions (temperature = 170°C, liquor-to-wood ratio = 5 L/kg, and 19% sodium hydroxide charge on the ovendry sawdust). The pretreatment of feedstock clearly facilitated delignification. After a cooking time of 90 min, the kappa numbers were 47.6 for the untreated birch and 10.3 for the hot water-treated birch. Additionally, the amounts of hydroxy acids in black liquors based on the pretreated sawdust were higher (19.5-22.5g/L) than those in the untreated sawdust black liquors (14.8-15.5 g/L). In contrast, in the former case, the amounts of acetic acid were lower in the pretreated sawdust (13.3-14.8 g/L vs. 16.9-19.1 g/L) because the partial hydrolysis of the acetyl groups in xylan already took place during the hot water extraction of feedstock. The sulfur-free fractions in the pretreatment hydrolysates (mainly carbohydrates and acetic acid) and in black liquors (mainly lignin and aliphatic carboxylic acids) were considered as attractive novel byproducts of chemical pulping.

Röntgenbeugungsuntersuchung an geschmolzenem Selen und Tellur sowie an Legierungen des Systems Selen—Tellur/ X-ray Diffraction Study of Molten Selenium, and Tellurium and of Molten Selenium — Tellurium-Alloys

1975 ◽  
Vol 30 (12) ◽  
pp. 1633-1639 ◽  
Author(s):  
W. Hoyer ◽  
E. Thomas ◽  
M. Wobst
Keyword(s):  
Chain Length ◽  
Short Range ◽  
Short Range Order ◽  
Coordination Shell ◽  
Range Order ◽  
Average Chain Length ◽  
X Ray Diffraction ◽  
Coordination Numbers ◽  
Nearest Neighbours ◽  
Increasing Temperature

Abstract At temperatures just above the melting point molten Selenium seems to be a mixture of long chains and eight-membered rings. With increasing temperature the number of rings and the average chain length decrease. At 460 °C the average chain length lies in the range of 10 atoms.In a slightly supercooled Tellurium-melt the number of first neighbours is two. The atoms are arranged in chains. Selenium rich Se-Te-alloy-melts are built up of mixed chains. It seems to be possible, that a smaller part of atoms forms Se6Te2 rings. At Tellurium concentrations higher than approximately 50 at.-% the chainlike structure with two next nearest neighbours changes to a disturbed Arsen-like short range order. The number of electrons in the first coordination shell, the short range order parameter introduced by Cowley and the partial coordination numbers show that Se-Te-alloys are of the "solution system" type, but in the whole concentration range for each atom there is a tendency to have "strange coordination".

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