Effect of Polysaccharides on Dehydropolymerization of Coniferyl Alcohol

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Molecular weights of DHPs of coniferyl alcohol prepared in the presence of beech hemicellulose and pectic acid a little increased as compared with that of DHP prepared in the absence of the polysaccharides. However, the molecular weights of the DHPs were still about a half of that of conifer MWL. The amounts of degradation products and functional groups of the DHPs suggested a general resemblance in the mode of interphenylpropane linkages between the DHPs and conifer MWL. As main differences the DHPs gave higher amounts of coniferyl aldehyde and vanillin in acidolysis and of phenolic hydroxyl- and 6-hydroxybenzyl alcohol groups

<Original>Dehydrogenative Polymerization of Monolignols by Peroxidase and H_2O_2 in a Dialysis Tube. I. : Preparation of Highly Polymerized DHPs

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Coniferyl alcohol gave a highly polymerized DHP whose molecular weight was higher than that of bamboo MWL by dialysis membrane method. The DHPs obtained by this method were almost insoluble in any solvents but swelled in DMSO, DMF, formamide and pyridine. The molecular weight of soluble fraction of the DHPs showed to be higher than that of the DHP prepared by "Zutropf" method on gel nitration chromatography with Sephadex LH-60 but smaller than that of bamboo MWL with Sephadex G-200. However, thermal softening point (Ts) (175℃) of the total DHP obtained by dialysis membrane method was higher than that of bamboo MWL (160℃). Thermal softening points of DHPs were shifted to the higher temperature with increase of peroxidase concentration in the dialysis tube. The results seem to indicate that a concentrated enzyme solution is required to prepare the highly polymerized DHP

<Review Article>Characterization and Degradation Mechanisms of Wood Components by Steam Explosion and Utilization of Exploded Wood

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました

Acidolysis of Bamboo Lignin II : Isolation and Identification of Acidolysis Products

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Guaiacyl, syringyl and ρ-hydroxyphenyl monomers which are expected by cleavage of the β-ether bonds in arylglycerol-β aryl ether structures have been isolated and identified in the acidolysis products of a bamboo MWL by various methods such as IR and NMR spectrometry. ω-Hydroxysyringylacetone was the predominant product in monomeric fraction followed by w-hydroxyguaiacylacetone. DL-Syringaresinol and DL-episyringaresinol were isolated from dimeric fraction and identified by melting point, UV, IR, NMR and mass spectrometry. These findings in addition to previous results indicate that the bamboo MWL is a mixed polymer of guaiacyl and syringyl propanes and a small amount of ρ-hydroxyphenylpropane connected through similar linkages found in spruce MWL

Structural Elucidation of Bamboo Lignin by Acidolysis and Ozonolysis I.

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Bamboo lignin was completely degraded into the oligomers composed of monomeric to pentameric products by acidolysis and mild ozonolysis. Model experiment showed that the phenylcoumarone moiety which is known to be produced from the phenylcoumarane structure in lignin in acidolysis is cleaved almost quantitatively to 5-acetyl derivatives and p-hydroxybenzoic acid derivatives by the mild ozonolysis (-70℃). From the monomer fraction of the ozonolysis products of the lignin residue by acidolysis p-hydroxybenzoic acid derivatives (XXI, XVII), methyl p-hydroxybenzoate derivatives (XXII, XXVI, XXVIII), p-cresol derivatives (XVIII, XXIII), p-hydroxybenzaldehyde derivatives (XX, XXV, XXVII), p-hydroxybenzylmetyl ether derivatives (XIX, XXIV) and dimethyloxalate (XXIX) were obtained, respectively

Dehydrogenative Co-polymerization of d-Catechin and Coniferyl Alcohol

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。To elucidate the possible occurrence of co-polymers of phenolic extractives and lignin in woods af-catechin was dehydrogenated in the presence of coniferyl alcohol with peroxidase and H_2O_2. Molecular weight distribution, UV spectra in the presence and absence of AlCl_3, methoxyl content and the degradation of the DHP by acidolysis, and by KMnO_4 oxidation after methylation showed that the DHP is a co-polymer, which1 may be linked at C5' of B rips; of d-catechin and C5 of coniferyl alcohol

Acidolysis of Bamboo Lignin III : Estimation of Arylglycerol-β-aryl Ether Groups in Lignins

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。The amounts of both uncondensed and condensed types of arylglycerol-α, β-diaryl ether groups in a bamboo, beech and a conifer (Thuja standishii) MWL's were estimated by gasliquid chromatography of arylacetones as acidolysis monomer and by spectral analysis of phenolic hydroxyl groups released after mild acidolysis and acidolysis of the MWL's, respectively. The experimental results showed that the amounts of α-aryl ethers were between 0.07 and 0.09 and those of β-aryl ethers were 0.56 (bamboo), 0.51 (beech) and 0.35 (Thuja)/C_6-C_3 of which uncondensed types amounted 0.25, 0.26 and 0.18, respectively. It was tentatively concluded that the polymeric system of the bamboo lignin is composed of about 10:68: 22 of ρ-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol via similar linkages found in spruce lignin and ρ-coumaric acid (O.O7/C_6-C_3) is esterified at the terminal γ-carbons of the side chains of the polymeric system

Dehydrogenative Polymerization of 3,5-Disubstituted p-Coumaryl Alcohols

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。3,5-Disubstituted p-coumaryl alcohols (3-methoxy-5-iodo-, 3,5-diiodo-, 3-methoxy-5-nitro-, 3,5-dinitro-, 3,5-dimethoxy- and 3,5-dimethyl-p-coumaryl alcohols) were synthesized and dehydrogenated to their dimeric compounds with ferric chloride in dioxane (nonpolar solvent) and acetone-water (polar solvent), respectively. Yields of the β-ethers were, for example, 85 % (sinapyl alcohol) and 86 % (3, 5-diiodo-p-coumaryl alcohol) in dioxane, and 11% (the former) and 80 % (the latter) in acetone-water, respectively. These results suggest that the most effective factor in the radical coupling of these alcohols is the electronic effects of the substituent groups, but not the steric hindrance. Syringylglycerol-β-sinapyl ether was obtained in a high yield from sinapyl alcohol when dioxane was used as a solvent

Steam or Heat Fixation of Compressed Wood

Dimensional stability can be improved by either steaming or heating wood while the wood is in a compressed state. This study investigated the effect of steam or heat on fixation of compression set and the effect of these treatments on hardness, mechanical properties, and color of compressed and uncompressed wood specimens. To determine the effect of steaming before and after compression set, one group of wood specimens was steamed and then compressed, and another group was compressed and then steamed. Simple boiling and cyclic swelling tests were used to evaluate recovery of compression set. Hardness of compressed specimens was measured by the Brinell test. A two-point bending test on noncompressed specimens was used to calculate moduli of elasticity and rupture. A L-a-b color system was used to determine color changes. Compressed wood steamed for 1 min at 200 C or 8 min at 180 C showed no recovery of set, large increases in hardness, minimum decreases in mechanical properties, and slight darkening. We conclude that almost complete fixation of compression set in wood can be achieved by steaming compressed wood