Isolation from wood

HemiceUulose is a mixture of amorphous branched-chain polysaccharides consisting of a few hundred sugar residues. They are easily hydrolyzed to monomeric sugars and uronic and acetic acids. Many different hemiceUuloses have been isolated from wood. 

The bicyclic ketone eremophilone 93 (Structure 4.27) was first isolated from wood oil of Eremophila mitchelii. It is also found in many other oils. allo-Er-emophilone 94 is also structurally related. 

The fact that glucomannan is obtained from GDP-D-mannose as substrate suggests that the particulate enzyme contains an epimerase which converts GDP-D-mannose to GDP-D-glucose. However, such an epimerase has not been observed. In this connection cellulose isolated from wood contains a considerable amount of D-mannose. 

Searching for evidence on the nature of the bond, we conducted a spectroscopic study of lignins isolated from wood by ethanolysis (P) and found, as expected, that 0-keto groups did not appear in the lignins until... 

In this work we have, in a preliminary way, extracted periodate lignin by the continuous dioxane-dimethoxypropane-HCl procedure and obtained only about 11% of a soluble material which had the same infrared spectral characteristics as the lignin isolated from wood. The gel-like residue showed evidence of having undergone the same reaction but remained insoluble. This seemed to indicate that the reaction alone was not enough to confer solubility. 

Goodell, B., Jellison, J., Liu, J., Daniel, G., Paszczynski, A., Fekete, F., Krishnamurthy, S., Lu, L., and Xu, G. (1997). Low molecular weight chelators and phenolic compounds isolated from wood decay fungi and their role in the fungal biodegradation of wood. J. Biotechnol. 53,133-162. 

The earliest expts devoted to the nitration of lignin, previously isolated from wood pulp by means of HC1, were reported by Hagglund (Ref 3). Lignin mixed with fuming nitric acid... 

Two naphthofurandiones, namely the 2-ethyl derivative of 84 and 89, were isolated from heartwood of P. peroba, in addition to lapachol, lapachone, and benzochromendiones (68N38). Related quinones 90 (mixtures of enantiomers) were isolated from wood of Rademachera sinica (81JCS(P1)2764). Helicquinone (91) was isolated from Helicteres angustifolia (87P578) and haemoventosin (92), a colored compound, was isolated from a lichen, Haematomma ventosum (71ACS483). 

Cellulose is insoluble in most solvents including strong alkali. It is difficult to isolate from wood in pure form because it is intimately associated with the lignin and hemicelluloses. Analytical methods of cellulose preparation are discussed in the section on Analytical Procedures. ... 

Polyisoprenoid alcohols consisting of 9 to 20 isoprene units have a widespread occurrence as indicated by their presence in the leaves of higher plants, mammalian tissues, and microorganisms. Most of the polyprenols isolated from higher plants consist of trans and cis isoprene units with the exception of solanesol, which is composed of all-trans isoprene units. The arrangement of trans and cis units in these polyprenols has been determined from a consideration of the mechanism of the formation of betula-prenols, C(30)-C(45), isolated from wood tissue of Betula verrucosa (9). However, up to the present there has been no direct evidence to prove the location of the internal trans and cis units. 

Bird and Ritter isolated, from wood of white oak, a chlorine holocellu-lose which contained all of the 0-acetyl groups present in the wood. Mitchell and Ritter later extracted a chlorine holocellulose from sugar maple with water and obtained a xylan in a yield of 3.4% of the wood. This polysaccharide contained 9.2% of 0-acetyl groups. A xylan which had been obtained in the same way, from aspen, by Wise and Jones, was, on treatment with periodate, oxidized almost to completion. When the wood itself was similarly treated, most of its xylan escaped oxidation. Although it appears evident that all of the xylan in the wood could not possibly have been accessible to the aqueous reagent, it was concluded that the lack of oxidation was most probably due to the fact that the native xylan was partly 0-acetylated. After treatment of wood from Eucalyptus regnans with methanol at 150°, Stewart and coworkers obtained, on extraction with water, a xylan (in a jdeld of 3.7%) which contained 5-6% of acetate... 

Cedronolactone B (29) and cedronolactone C (30), isolated from wood of Simaba cedron were shown, exhibited in vitro cytotoxicity (IC50 6.5 and 49 pg/mL) against P-388 lymphocytic leukemia cells [19]. 

Two new quassinoids (34) and (35) with a presence of a 1,2-seco-1 -nor-(5 - 10)-afo o-picrasan-2,5-olide skeleton were isolated from wood Eurycoma longifolia Jack [15]. 

Quassinoid glycosides named bruceantinoside (72) and the new bruceanic acids B (73), C (74), and D (75) were isolated from wood Brucea antitfysenterica [39-40], Bruceanic acid D (75) was cytotoxic against P-388 (ED50 0.77 pg/mL). 

Lignins. Lignins are amorphous, cross-linked phenolic polymers that occur uniquely in vascular plants and comprise 20-30% of most wood. Lignins isolated from wood are polydisperse, with molecular weights in the range of thousands to hundreds of thousands (4). Lignins are produced almost exclusively from three cinnamyl alcohols, whose structures are shown in Chart I. These structural units have propylphenyl carbon skeletons and differ... 

Crystallites of cellulose have been isolated from wood pulp in this way by treatment with acid to hydrolyze and remove the amorphous regions. Typical dimensions of the remaining crystallites were 46 nm long by 7.3 mn wide, corresponding to bundles of about 100 to 150 chains in each crystallite. 

The alkali metals are soft metallic solids ( FIGURE 7.19). AH have characteristic metallic properties, such as a silvery, metallic luster and high thermal and electrical conductivity. The name alkali comes from an Arabic word meaning ashes. Many compounds of sodium and potassium, two alkali metals, were isolated from wood ashes by early chemists. 

Most methods for LCC isolation from wood require ball milling, which is carried out so that the cell wall matrix can be degraded and the lignin and LCC fragments can be released and extracted. Extraction of the milled wood with 96% dioxane produces crude milled wood lignin (MWLc) [24]. 

Before jumping into our analysis of the poisonous amount of oxalie acid, it may be useful to become familiar with some of its properties. Oxalie aeid is a white crystalline sohd (most acids are not liquids 4.10), which dissolves quite readily in water (Fig. 4.21). It was first isolated from wood-sorrel by a French scientist in 1688, and subsequently, in 1776, noted Swedish ehemist Carl Wilhelm Scheele... 

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