The Acylation of Polyuronides with Formamide as a Dispersing Agent

Carson, John H.; Maclay, W. D.

doi:10.1021/ja01210a034

Cited by 78 publications

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“…The hemicellulose was converted to the fully substituted acetate derivative without any apparent depolymerizatioil (21). Osmotic pressure measurements indicated a numberaverage ~nolecular weight of 45,900.…”

Section: And Discussionmentioning

confidence: 99%

“…These po1ysaccha1-ides are all, with one possible exception (23), linear, and contain side chains of a-1,2-linlced 4-O-methyl-~-glucurollic acid residues. Of the species so far studied, European (21) and American (23) beech, white birch (16), yellolv birch ( 2 5 ) , sugar maple (25), and trembling aspen (26) all contain hemicelluloses with 10-11 xylose residues per acid side group. The present hernicellulose apparently possesses relatively more acid side chains.…”

Section: And Discussionmentioning

confidence: 99%

“…After being stirrccl over night, the gelati~ious reaction mixture was poured into ice water 1vit11 vigorous stirring and recovcrccl 3s describecl by Carson arld klaclay (21). A second esterilication was carriccl out in the same way altho~1g11 nrithout :ldclition of formamicle.…”

Section: Pvefiaration Of the -Lcetyl Derivative Of T L~e Iiemicellz~mentioning

confidence: 99%

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The Hemicellulose of White Elm (Ulmus Americana) Ii. Constitution of the Methyl Glucurono-Xylan

Gillham¹,

Timell²

1958

Can. J. Chem.

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Section: And Discussionmentioning

confidence: 99%

Section: And Discussionmentioning

confidence: 99%

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The Hemicellulose of White Elm (Ulmus Americana) Ii. Constitution of the Methyl Glucurono-Xylan

Gillham¹,

Timell²

1958

Can. J. Chem.

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“…! l cetylation of the ~Ienricellz~lose Acetylation of the hemicellulose was carried out as described previously (24) essentially according to the method of Carson and A'Iaclay (33). Two acetylations gave a product soluble in chloroform-ethanol (9:l v/v).…”

Section: Qllanfitative Ilnalysis Of the Nelltral Componentsmentioning

confidence: 99%

The Constitution of a Hemicellulose From Sugar Maple (Acer Saccharum)

Timell¹

1959

Can. J. Chem.

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Partial hydrolysis of the main hemicellulose constituent of sugar maple (ilcer saccharntlz) has yielded D-xyloSe, D-galacturonic acid, 4-0-methyl-D-gl~rcuronic acid, and 2-0-(4-0-methyla-D-glucosyluronic acid)-D-xplose. Hydrolysis of the fully methylated polysaccharide gave a mixture of 2-0-and 3-O-methyl-D-xylose, 2,3-di-0-n1ethyl-~-xylose, 2,3,4-tri-O-methyl-~-xplose, and 2-0-(2,3,4-tri-0-n~etl~yl-a-~-gl~1cosyluronic acid)-3-0-methyl-D-sylose in a mole ratio of 3 : 111 : 1 : 12. The number-average degrees of polymerization of the native and the lnethylated polysaccharide were 205 and 149, respectively. These data indicate that the hemicellulose is composed of a linear chain of 1,4-linked P -D -x~~o s~ residues and that on the ax-erage every tenth residue of the chain carries a ternlinal 4-O-methyl-~-glucuronic acid residue attached through its C?. The structure of tile polysaccharide is similar to that of the main hernicellulose component of European beech, \\,bite birch, and yello\\-birch.Sugar maple is an inlportani hardwood species in the lort the astern part of this continent. Ritter and co-worlcers (1, 2) have st~idied the general conlposition of various he~nicellulose fractions from this wood and chromatographic evidence for the presence of 4-0-methyl glucuronic acid has been reported by Nelson and Schuerch (3). The structure of the same hemicellulose has been s t~~d i e d by Neubauer and Purves (4), who concluded that the polysaccharide ~7 a s composed of a branched baclcbone of 1,4-linked xylose residues, some of which carried terrniiial 0-methyl glucuro~~ic acid residues. I n a previous investigation (5) the molecular properties of a native cellulose from sugar maple were studied. The present paper is concerned with the constitution and properties of the main heniicellulose component of this species. RESULTS AKD DISCIiSSIONThe high pentosan content of the \vood (18.5%) indicated that the preponderant l~emicellulose \vas a xylan. When the mood was extracted wit11 alkali, a heinicellulose was obtained in a yield of 12.4%, giving D-x).~os~ and three uronic acid compounds on partial hydrolysis. The sugar acids were separated from the xylose oil ail anion exchange resin and the mixture obtained was resolved on a charcoal coluil~n to yield galacturonic acid, 4-0-illethyl gluc~~ronic acid, and an aldobiouronic acid. T h e hexuro~iic acids were identified cI~ron1atographical1~-whereas the structure of the aldobiouronic acid was proved by the following experiments.Reduction of the methyl glycoside methyl ester of the alclobiouro~iic acid followecl by l~ydrolysis gave D -X J~~O S~ and 4-0-methyl-D-glucose. When the neutral disaccharide was methylated to completion and hydrolyzed, :-1,4-di-0-rneth~~l-~-xylose and 2,3,4,6-tetra-0-niethyl-D-glucose were obtained. This evidence, together with the specific rotation of the compound (+100°) (G), sholvecl that the acid was 2-0-(~-O-1nethyl-or-~-~~1cosyluro1lic acid)-D-xylose.;\lIethanolysis of the fully methl.lated hemicell~ilose gave a inixture of glycosides...

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“…The reaction mixture was cooled with tap water for the first half hour and then shaken mechanically a t room temperature for 5 hours, after which it was kept a t +4' C for 3 days, the reaction flask being opened occasionally during this time. The mixture was poured into ice water (3 liters) with vigorous stirring and washed on a large Buechner funnel, first with ice-cold 2% hydrochloric acid (30) and subsequently with cold distilled water until neutrality. After the water had been replaced by ethanol and the alcohol by petroleum ether (b.p.…”

Section: Preparation Of the Acetylated Iiemicellulosementioning

confidence: 99%

The Constitution of a Methyl Glucuronoxylan From Kapok (Ceiba Pentandra)

Currie¹,

Timell²

1959

Can. J. Chem.

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The seed hairs of lcapolc (Ceiba penlandra) on alkaline extraction have yielded a hcrnicellulose composed of xylose and uronic acid residues. Partial hydrolysis of the polysaccharide gave 2-0-(4-0-methyl-~-~-9-lucopyranospl~1ronic a~i t l ) -D -~y l o p y r a l~~s~, 4-0-methyl-D-glucuronic acid, and, probably, galacturonic acid. Hydrolysis of the fully methylated hemicellulose yielded a mixture of 2-0-and 3-0-meth>~l-~-sylose, 2,s-di-0-methyl-D--lose, 2,3,4-tri-o-rnethyl-~-xylose, and 2-0-(2,3,4-tri-0-methy~-a-~-~copyra1ios)~1roic acid)-3-0-methyl-D-xylopyranose in a niolar 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 rnolccule contains approximately 180 1,4-linked P-D-~ylopyraII~se residues, one eighth of which carry a singlc tcrrnilial side chain of 4-0-methyl-D-glucuronic acid, attached through a n a-glycosidic bond to C ? of the sylose. The xylan frameworlc contains, on the avcrage, 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 4-0-methyl glucuronosylan present in the seed hairs of rnillcweed floss.In previous investigations the general cheinical composition of the seed hairs of kapok was studied (1) as well as the molecular characteristics of their cellulose component (2, 3). The present paper is concerned with the structure and properties of the main heinicellulose constituent. RESULTS AND DISCUSSIONThe high pentosan content (24.4Y0) of the extractive-free seed hairs indicated that the predominant he~nicellulose was based on xylose residues. The considerable amounts of acetyl (8.0%) and uronic anhydride (6.6y0) groups present as well as the forlliation of a methylated glucuronic acid on hydrolysis of the fibers suggested that the polysaccharide in its native state was a partially acetylated methyl glucuronoxylan. When kapok fibers were extracted with aqueous alkali a deacetylated product was obtained in a yield of 18.870, containing 83.3y0 pentosan and with [a]; -G8O in water. Its content of ash, methoxyl, and uroilic anhydride indicated the presence of an average of 7.8 anhydroxylose units per methylated uronic acid.Partial acid hydrolysis of the hemicell~~lose gave a mixture of sugars which was resolved into a neutral and an acidic portion on a column of anion exchange resin. The neutral part contained mostly D-xylose which crystallized but also traces of glucose, mannose, arabinose, and rhamnose. Elution of the column with dilute acetic acid yielded three sugar acids, namely a monouronic acid, chromatographically identical with galacturonic acid, an aldobiouroilic acid, and a mono-0-methyl monouronic acid.The methoxyl content and equivalent weight of the aldobiouronic acid suggested that it consisted of a methoxyuronic acid linked to a pentose residue. A portion of the acid was c...

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The Acylation of Polyuronides with Formamide as a Dispersing Agent

Cited by 78 publications

References 0 publications

The Hemicellulose of White Elm (Ulmus Americana) Ii. Constitution of the Methyl Glucurono-Xylan

The Hemicellulose of White Elm (Ulmus Americana) Ii. Constitution of the Methyl Glucurono-Xylan

The Constitution of a Hemicellulose From Sugar Maple (Acer Saccharum)

The Constitution of a Methyl Glucuronoxylan From Kapok (Ceiba Pentandra)

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