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Crystallized mesoporous carbon was produced from ligno-p-cresol, a lignin derivative obtained by phase separation with p-cresol and sulfuric acid, onto which 3% nickel and 2% calcium were co-loaded, by carbonization at 900°C. Subsequent pulverization followed by soaking in acid improved the crystallinity of carbon with an increased volume of mesopore, attaining approximately 90% and 99% removal of nickel and calcium, respectively. These aspects implied both enhancement of electroconductivity and liquid phase adsorption capacity of the carbon with a good outlook on the recovery and reuse of the two metals. In particular, combination of wet milling using small beads and mild soaking with diluted acid was appropriate in respect of relevant properties of the carbon, including the particle size. It can thus be concluded that incorporation of such post-treatments into the manufacturing process of carbon products is greatly advantageous.

相分離系変換システムにより調製されるリグノフェノールを用いて，リグノフェノールと木粉よりなる複合成形体を熱圧成形により作製し，それらの物性を評価した。複合成形体の曲げ強さ及び曲げ弾性率は，圧締圧力の上昇やリグノフェノール配合量の増加にともない概ねは上昇したが，高配合量の高圧締圧力条件で低下し，その原因はリグノフェノール分子の熱的構造転換により生じる気体によるものと推察された。また，吸水率と吸水厚さ膨潤率は，リグノフェノール配合量の増加にともない低下し，吸水率は圧締圧力に，吸水厚さ膨潤率はリグノフェノールの物性に大きく影響された。なお，成形時にNaClやCaCl2・2H2Oを少量添加することにより，曲げ強さや抗吸水性能は大幅に向上し，その効果は，CaCl2・2H2Oの添加がNaClの添加に比べて高い結果となった。

For the recovery of precious metals like Au (III), Pd (II) and Pt (IV), dimethylamine immobilized crosslinked, lignophenol gel, a novel lignin gel, was prepared from wood powder. Its adsorption behavior for Au (III), Pt (IV) and Pd (II) ions in hydrochloric acid medium was studied. The gel was found to adsorb all three precious metals quantitatively irrespective of the concentration of hydrochloric acid while it was found to be inert towards other base metals such as Cu (II), Zn (II), Ni (II), and Fe (III) . This kind of performance of the novel gel can be promising for the low cost recovery of precious metals from electrical and electronic wastes by utilizing nature friendly materials.

Conventional metallurgical processing of precious metals involves the use of large amounts of toxic chemicals. Realizing a need to develop environmentally benign metallurgical technology for precious metals, we prepared two types of adsorption gels, containing primary amine and ethylenediamine functional groups and abbreviated as PA−lignin and EN−lignin, respectively, from wood powder. Both of these adsorption gels were found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) from weak to strong hydrochloric acid media. In contrast, base metals such as Cu(II), Fe(III), Ni(II), and Zn(II) were almost not adsorbed on either gel. The above-mentioned precious metals were adsorbed on the gels according to the Langmuir adsorption model, and the highest maximum adsorption capacity was observed for Au(III). The formation of ion pairs of metal−chloro complex anions and protonated adsorption gels in acidic media was proposed to be the main adsorption process. However, in the case of Au(III) adsorptio...

A photochemical solar cell sensitized with a lignophenol, which has been directly synthesized from lignocellulosics through the phase-separation system, on a nano-porous TiO2 film electrode was developed and improved by stirring, reflux and saturation in an acetone solution. Hinoki (Chamaecyparis obtusa)-lignophenol (p-cresol type, HKLC), Beech (Fagus crenata)-lignophenol (p-cresol type, BCLC), second derivatives-I of HKLC and BCLC (HKLC413, BCLC413) and second derivatives-II of HKLC and BCLC (HKLC443, BCLC443) were used as photo-sensitizers. The conversion of visible light from 150-W Xe lamp through a L41 UV cut filter into electricity was achieved with a sandwich-type cell consisted of FTO-glass-TiO2 film-lignophenol-electrolytes-Pt coated FTO. The open circuit photovoltage (Voc), the short-circuit photocurrent density (Isc), the fill factor (FF) and the photo-electricity conversion efficiency (η) for the cell with HKLC413 saturated on TiO2 electrode were estimated under 85.0 mW cm−2 visible light irradiation for 0.51 V, 10.23 mA cm−2, 0.59 and 3.61% respectively. On the other hand, the cell with HKLC saturated only on the surface of TiO2 electrode was estimated for η = 0.81%. Moreover, the amounts of HKLC413 and HKLC443 on the electrodes extracted by 1.0 M NaOH were larger than the amount of HKLC evaluated by UV–vis spectroscopy. After the extractions were carried out in NaOH, only both HKLC413 and HKLC443 were remained in electrodes with slight yellow appearances. These results indicated that lignophenols were adsorbed on the inner part of porous TiO2 electrodes. Consequently, the performances of these cells were strongly influenced by the molecular sizes and the structures of lignophenols.

A polymer structure and function of lignophenol was examined by various structural analysis of lignophenols fractionated with preparative SEC. The base unit of lignophenol is 1,1-bis (aryl) propane-2-O-aryl ether unit in all the molecular weight areas by NMR analysis. But the amounts of combined cresol and phenolic hydroxyl groups were increased with decreasing molecular weight of fractionated lignophenols. The protein-adsorbing capacities and thermoplastic property of fractionated lignophenols differed with the molecular weights.

The molecular morphology of lignophenol and conventional lignins were analyzed with SEC-MALLS system. MALLS analysis has been used as method for absolute molecular weight of polymers. However determination of absolute molecular weight of lignin is difficult due to divisively and complication of lignin structure. But the difference in the molecular weight of lignin determined by MALLS and conventional calibration methods using linear polystyrene standard can show the difference of molecular morphology of lignin. The molecular morphology of lignocresol was more spreading and linearity, compared with other lignins. It was suggested that this characteristic of lignophenol is concerned with thermoplasticity of lignophenol that other lignins do not have.

Through the phase-separation reaction system with sulfuric acid, lignocellulosics which form an interpenetrating polymer network within the cell wall were separated almost quantitatively into different phases within 20 min. The yield of carbohydrate of acid layer after the 60 min phase-separation treatment was 71% of raw material (98% of carbohydrate). A total yield of original lignin without grafting cresol in lignocresol, acid phase sugar and cresol phase sugar was 96% of raw material at the 60 min phase-separation treatment. It was possible to control conversion pattern of lignocellulosics component with the quantity of the phenol derivatives.

Three different kinds of adsorption gels, viz., cross-linked lignophenol, cross-linked lignocatechol, and cross-linked lignopyrogallol, were prepared by the chemical modification of wood lignin. The adsorption behaviors of these gels for Au(III) along with some other metals were studied and compared to that of activated carbon. All three gels were found to be more selective for Au(III) than activated carbon with comparable adsorption capacities. Of the lignin gels, cross-linked lignophenol exhibited the highest selectivity for Au(III) and was found to be almost inert toward other metals tested. All three novel lignin gels as well as activated carbon were found to be efficient in reducing Au(III) to elemental gold, as indicated by XRD analysis of the sorbents taken after adsorption. However, a significant difference between the novel sorbents and activated carbon was found, i.e., the latter exhibited no selectivity among the metal ions tested, whereas the novel gels have a high selectivity to only Au(III)....

Peroxidase-catalyzed polymerization of lignin-based macromonomer, lignocresol, which was prepared by the phase-separation system of lignin and p-cresol in aqueous sulfuric acid, was carried out for the first time in aqueous organic solvents to give insoluble polymers in 55% yield. It was found that the polymerizability of lignocresol by peroxidase was enhanced by the introduction of p-cresol in lignin side-chains compared to that of original lignin. Copolymerization of lignocresol with p-cresol gave the corresponding copolymers in high yields. From the IR results, lignocresol might be polymerized through a phenoxyl radical. The pyrolysis gas chromatography-mass spectrometry (GC-MS) analysis of the polymers obtained indicated that the polymerization of lignocresol involved mainly the oxidative coupling at the introduced p-cresol. The thermal properties of the polymers obtained were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements, suggesting that the polymers have high thermal stability according to the crosslinked structures. Copyright © 2005 John Wiley & Sons, Ltd.

溶媒可溶で分子設計が可能な森林資源由来の天然リグニン誘導体ポリマーであるリグノフェノール (LP) とナノ多孔質酸化チタン電極を組合せた光電変換デバイスは, 可視光照射下, 安定した光電変換能力を示した. UV-vis分光の結果, 各LPはそれぞれ可視光領域で固有の波長を吸収し, ヒドロキシル基が重要な役割を果たした. LP二次誘導体は可視光吸収が大幅に増大した. LPは光照射により一重項励起し, 蛍光を発した. 分子内に複雑な内部変換などの緩和機構を有し, 導入フェノールによっては項間交差も見られた. CV分析の結果, 比較的安定なカチオンラジカルを生じる構造を有し, 電荷分離が可能な物質であった. さまざまなLPを用いて比較した結果, LP/酸化チタン錯体が重要な電子注入ルートであり, ヒドロキシル基以外にも1, 1-ビス (アリル) プロパン型ユニットが重要な相互作用をしていることが示唆された. ヒノキリグノ-p-クレゾール二次誘導体-I (HKLC413) を用いたセルで0.5V, 4.0mAcm-2, η=0.8%の光電変換能力を示した. 天然に豊富に存在する未利用炭素資源誘導体ポリマーと酸化チタンを組合せることで光励起による電荷分離が生じ, 色素増感太陽電池として機能した.

論文(Article), Crosslinked lignocatechol gel was prepd. by immobilizing catechol onto wood lignin followed by crosslinking. The adsorption behavior of crosslinked lignocatechol was studied batchwise by varying different parameters like pH, initial concn. of metal ions and shaking time. Based on the results obtained in batchwise expts., breakthrough profiles were examd. using a column packed with crosslinked lignocatechol gel for the sepn. of small concn. of Pb(II) from an excess of Zn(II) followed by elution tests. Ten consecutive adsorption-elution cycles were conducted so as to check the stability and efficiency of the gel for recycling purpose. A const. efficiency was obsd. that reveals the feasibility of recycling of the gel. Cation exchange mechanism is postulated as the predominant process of the adsorption.

A series of new lignin derivatives (lignophenols) containing phenol, p -cresol, catechol, resorcinol and pyrogallol synthesized from Hinoki ( Chamaecyparis obtusa ) and Douglas fir ( Pseudotsuga menziessi ) as softwood and beech ( Fagas crenata ) as hardwood was investigated as sensitizers for a dye-sensitized solar cell (DSSCs) of porous TiO 2 under the irradiation of 150 W Xe lamp. For example, LPs–DSSCs of hinoki-ligno- p -cresol, directly derived from hinoki native lignin showed V oc =0.34 V, I sc =0.65 mA cm −2 , ff=0.49 and η =0.11% under AM 1.5 (100 W m −2 ). The strong interactions between lignophenols and TiO 2 surface were estimated by UV-Vis and FT-IR spectra. The importance of interactions between phenolic hydroxyl groups and TiO 2 surface was discussed by FT-IR, solid UV-Vis spectra and 1 H NMR. The effects of chemical modifications were discussed using acethylated lignophenols (LPsOAc) or re-cycled lignophenols, treated by 0.5 M NaOH at 413 K (LPs–SF413) or 443 K (LPs–SF443). These results implied interactions between LPs and TiO 2 were consisted of anchors and stacking on TiO 2 .

Through the phase-separation system composed of phenol derivatives and concentrated acid, lignocellulosics were separated to highly hydrolyzed carbohydrates and lignin-based material (lignophenols) quantitatively. Lignophenols mainly composed of 1, 1-bis(aryl) propane type units had unique properties such as high phenolic property, obvious phase transition point and switching function (nucleophilic attack of Cα-phenoxide to adjacent Cβ followed by the cleavage of aryl ether linkages). Controlling the hydrolysis of carbohydrates in the system, lignophenol-carbohydrate (LC) composites containing lignophenols and carbohydrates which left no fibrous structures were prepared in the yield of 80-90% from the wood meals. LC composites had significant thermal plasticity at around 170°C. The softening point of the acetylated LC composites was much lower than that of the original ones due to blocked hydrogen bonds of lignophenol and carbohydrates. On the other hand, the hydroxymethylated LC composites (grafted phenol derivative in lignophenol; p-cresol) had no softening point because of linked structures formed in lignophenol. The hydroxymethylated LC composites (phenol derivative: 2, 4-dimethylphenol), however, softened at 170°C because lignophenols in the composites were hydroxymethylated at terminal phenolic nuclei to give linear type polymer. The molds from the acetylated LC composites had the highest density and excellent water resistance. The hydroxymethylated LC molds with p-cresol type lignophenol showed high dimensional stability having slight water absorption and volumetric swelling, because of porous structures and the network of lignophenol. LC composites and molds could be separated into lignophenol and carbohydrate moieties efficiently by simple solvent extraction or using switching function of lignophenol.

For effective production of crystallized carbon (T-component) usable for electromagnetic shielding (EMS) from Lignocresol (LC) by nickel-catalyzed carbonization, the promotion effect of calcium co-loaded was investigated in the reaction at 900°C for 1h. It was shown that suitable loadings of nickel and calcium were both 8 wt% for char in terms of the formation of T-component and EMS capacity, and the Ca/Ni ratio of 1.0 was also optimal for other nickel loadings. A similar aspect was observed in the same carbonization of acid-demineralized alkali lignin (DAL) used for comparison. These results supported a previously proposed interaction between nickel and calcium and made the action and role of calcium clear.

Enzymatic degradation of two lignin-based polymers (lignophenols), lignocatechol and lignocresol, prepared by selectively grafting catechol and p-cresol to Cα positions of lignin, respectively, were carried out in aqueous organic solvents. Both lignophenols showed high reactivity in the peroxidase-catalyzed oxidation. Structural analyses by NMR spectroscopies revealed that the degraded lignophenols contained aliphatic chain content, which might be mainly formed in the reduction of the intermediate initially generated by the aromatic ring cleavage. Lower amount of aromatic units in the lignophenols after degraded by peroxidase also indicted the cleavage of aromatic rings. Due to the substitution of phenols at Cα positions of lignin, the degraded lignophenols did not have carbonyl structure, which was abundant in the biodegradation products of native lignin. The two lignophenols were also degraded by Rhus vernicifera laccase. But the degree of degradation was lower than that of the degradation by peroxidase, which might be due to the low activity of laccase on the lignin moieties in lignophenols.

Through the phase-separation system composed of phenols and concentrated acid, the phenol components are selectively hybridized into C1-positions of phenylpropane units of native lignin to give 1, 1-bis(aryl)propane-type linear polymers (lignophenols) quantitatively. Lignophenols have unique properties such as high phenolic activity and obvious phase transition. Furthermore, the functionality of lignophenols was able to be controlled using the intramolecular switching function: Under alkaline condition, C1-phenols in lignophenols nucleophilically attack adjacent C2 as switching devices, followed by the cleavage of aryl ether linkages. In ligno-p-cresol and ligno-2, 4-dimethylphenol with similar switching functionality and structural characteristics, ligno-p-cresol was highly hydroxymethylated (HM) on the cresolic nucleus to give network-living pre-polymer. On the other hand, ligno-2, 4-dimethylphenol having reactive sites mainly on the terminal unit gave linear-living pre-polymers. The structures of polymerized lignophenols were controlled by mixing ratio of HM-ligno-p-cresol and HM-ligno-2, 4-dimethylphenol or by the hybridization ratio of p-cresol and 2, 4-dimethylphenol in lignophenols followed by hydoxymethylation. The resulting polymer chains were cleaved at the switching points to give low molecular weight subunits by the switching function. Recyclable composites were prepared by the combination of cellulose and HM-lignophenol (the mixing ratio of HM-ligno-p-cresol to HM-ligno-2, 4-dimethylphenol was 1:0, 1:1, 0:1, respectively). The composites had glossy surfaces and looked like wood. The dimensional stability of composites was improved significantly with increasing mixing ratio of HM-ligno-p-cresol to HM-ligno-2, 4-dimethylphenol. Using the switching functionality of lignophenol, the composites were re-separated into lignophenols with low molecular weight and cellulose.

1,1-Bis(aryl) propane-2-O-aryl ether-type lignin-based polymers, lignophenols (LPs) were synthesized through a phase-separation system composed of phenols and concentrated acid. LP with C1-p-cresol (LP-P) and LP-24X containing C1-2,4-xylenol had a similar phase-transition point, average molecular weight, frequency of phenols in the molecule and switching functionality (nucleophilic attack of C1-phenols to C2). LP-P, however, was hydroxymethylated (HM) at its reactive cresolic and terminal phenolic nuclei to give network-type structures on heating. On the other hand, LP-24X without a reactive point on the grafted nuclei resulted in the formation of linear-type structures. The structures of polymerized LPs were controlled by the grafting ratio of p-cresol and 2,4-xylenol in LPs. The resulting polymer chains were cleaved at the C2-aryl ether linkages to give low molecular weight subunits by the switching function of the C1-grafted unit. In order to use LPs as matrixes for various composites, HM-LP-P, HM-LP-24X, and HM-LP-P/24X, containing an equivalent amount of C1-p-cresol and C1-2,4-xylenol, were hybridized with powdery materials such as cellulose, glass, iron or talc by applying heat and pressure. The resulting HM-LP composites had a glossy surface and high dimensional stability because the polymerized HM-LPs' matrixes tightly bound fillers. Furthermore, using the switching functionality of LPs, the composites were re-separated into LP fractions and fillers. The physical and recycling properties of the composites were controlled by the structure of the LPs matrixes and/or the density, the morphology and the accessibility for reagents of the powdery materials.

Peroxidase-catalyzed polymerization of lignin-based macromonomers (lignophenols), lignocatechol and lignocresol, prepared by phenolation of lignin with catechol or p-cresol, was carried out in aqueous organic solvent mixtures. The two lignophenols were polymerized to give cross-linked polymers. The highest yield of polymerization (83%, w/w) was obtained with lignocatechol, and the maximum yield for the polymerization of lignocresol was 55% (w/w). Pyrolysis GC-MS analysis of polymers indicated that the polymerization of lignophenols involved the oxidative coupling of the introduced phenol derivatives.

Carbon molecular sieving membranes were prepared by pyrolysis of lignocresol derived from lignin by the phase-separation method. Lignocresol membranes formed by a dip process on a porous α-alumina tubing were carbonized at 400–800°C under nitrogen atmosphere. The thickness of the membrane formed on the outer surface of the substrate was about 400 nm judging from SEM observation. Gas-evolving behavior of lignocresol was measured using thermogravimetry-mass spectrometry (TG-MS). The gaseous products evolved from lignocresol included a number of fragments with higher molecular weights; whereas those from phenolic resin are mainly due to phenol and methylphenol. These evolved pyrolysis fragments effectively contribute to micropore formation of carbonized lignocresol membranes. Gas permeation rates through the membrane decreased in the order of increasing kinetic molecular diameter of the penetrant gas, and the membrane behaved like a “molecular sieve.” The permeation properties were dependent on heating conditions, and a pyrolysis temperature of 600°C gave the best membrane performance. Gas selectivities of the membrane prepared at 600°C were 50, 8, 290, and 87 for CO2/N2, O2/N2, H2/CH4, and CO2/CH4 at 35°C, respectively.

Lignocresol (LC), which is recovered from wood by adopting phase separation system with sulfuric acid/ cresol, was carbonized at 900°C for 1 h after loading with nickel alone or both nickel and sodium, and the crystal structure of carbon and the electromagnetic shielding (EMS) capacity at 50-800 MHz were evaluated for the resulting char. For comparison, four other isolated lignins were subjected to the same treatment and measurement. LC char could produce crystallized carbon (T-component) markedly by co-loading of nickel 8-9 wt% and sodium 8-10 wt% to exceed a practical standard of EMS capacity. 30 dB at 800 MHz, although nickel alone was ineffective. The capacity of the LC char with both nickel and sodium was superior or comparable to those of the corresponding other lignin chars. Without nickel, LC char resulting from the unique structure gave less amorphous carbon with larger EMS capacity than other chars. These results showed that LC was suitable as raw lignin for converting into EMS material by nickel-catalyzed carbonization.

Though the phase-separation system composed of the concentrated acid and p-alkylphenols, the lignin-based polymers (lignophenols) with the switching devices for the functionality control were synthesized. p-Substituted phenols grafted to C1 of the lignin side chain attacked C2 in alkaline media, followed by the cleavage of 2-O-aryl ether and the exchange of phenolic functionality from C1 phenols to lignin nuclei. Using 2, 6-dimethylphenol (the control device), the switching functions of various ligno-p-alkylphenols were controlled. There was a good correlation between the frequency of phenolic nuclei with C2-attackable OH and the depolymerization degree. Furthermore, compared with ligno-2, 4-dimethylphenol, the rate of alkaline depolymerization of ligno-p-n-propylphenol was lower, indicating that the switching functions of C1-grafted p-alkylphenols were affected to a larger extent by their steric factors rather than their electronegativity.

Through the phase-separation system, the functionality controllable lignin-based polymers (lignophenols) with 1, 1-bis (aryl) propane units were synthesized. Ligno-p-cresol with the reactive sites on the Cl-cresolic and the terminal phenolic units were hydroxymethylated (HM) to give network-type polymers by heating. On the other hand, ligno-2, 4-dimethylphenol with reactive sites only on the terminal phenolic units gave linear-type polymers. The polymerization of lignophenols could be controlled by mixing HM-ligno-p-cresol and HM-ligno-2, 4-dimethylphenol. Under alkaline conditions, the resulting polymers were depolymerized effectively to small fragments by the switching function (nucleophilic attack of C1-phenolic nuclei to C2). The recyclable composites with high dimensional stability were prepared by the combination of cellulose and HM-lignophenols. Using the switching function of lignophenols, the composites were re-separated into lignophenols and cellulose.

Phenolic lignin-based network polymers with structure-variable function have been designed, and a reaction process has been developed for synthesizing them directly from native lignins. The process includes a phase-separation reaction system composed of phenol derivatives and concentrated acid. The key point of the process is that lignin and carbohydrates, which form an interpenetrating polymer network within the cell wall, are separated into different phases and their modifications are controlled individually. The resulting lignin-based polymers (lignophenol derivatives) have unique functions, which conventional lignins do not have, in spite of retention of the original interunit linkages: these include highly phenolic property, no conjugated system, light colour comparable with native lignin, structure-variable function and solid-liquid transformation. These original functions are due to the selective hybridization of lignin structural units with monomeric phenol derivatives at C positions, leading to network structures composed mainly of 1,1-diarylpropane-type units. New types of applications of lignophenol derivatives using their original functions are described (biocatalyst system and lignin fibre composites).

The structural features of depithed bagasse lignin and its changes in soda cooking have been characterized in situ by the nitrobenzene oxidation, phenyl nucleus exchange and periodate oxidation methods. The bulk of bagasse lignin (∼ 75%) can be readily delignified in alkali below 100°C, and does not appear to be resulted from the cleavage of β-aryl ether structures. Concerning the reactivity of uncondensed structures, the p-hydroxyphenyl units were most labile to alkaline treatments, whereas the guaiacyl and syringyl units were removed nearly at the same rate. The residual lignin appears to be rather condensed and to contain an appreciable amount of guaiacyl diphenylmethane-like structures.

Periodate oxidation, because of its high selectivity in degrading phenolic nuclei, has been combined with nitrobenzene oxidation and phenyl nucleus exchange techniques to investigate the nature of wood lignin in situ. For both softwood and hardwood, the phenolic and etherified components of wood lignin have been shown to differ significantly in chemical composition, and the etherified lignin structure appears to be substantially more condensed.

A functional lignin-based material, lignocresol, was synthesized from eucalyptus wood meal by using phase separation treatment with p-cresol and 72% sulfuric acid. Lignocresol physically adsorbs Trichoderma reesei cellulase and functions as an immobilized cellulase. Lignocresol-immobilized cellulase was treated with acetone or ethanol to separate the enzyme and its support. Most lignocresol was dissolved in organic solvents and then precipitated in diethyl ether. The recovery yield of lignocresol using acetone was 85% and that using ethanol was 72%, with very low or negligible residual cellulase. Lignocresol is an innovative recyclable enzyme support that can be easily separated using only organic solvents after deactivation of the immobilized enzyme.

The chemical structures of lignocresols derived from native lignins by the phase-separative treatment with cresol and sulfuric acid were characterized by spectral analyses and chemical degradations. The changes in the structure of lignin during the conversion process were discussed. Lignocresol had few conjugated systems, being pinkish white, its brightness comparable to milled wood lignin. Spruce lignocresol included 0.64 mol/C 9 of cresolic nuclei in the molecule (0.9 mol/C 9 in birch lignocresol), 77% of which were linked to lignin Cα-positions through carbon-carbon linkages, 16% possibly to Cγ-positions, and the remaining 7% etherified to lignin side chains through its phenolic hydroxyl groups. The molecular weight (Mw) of lignocresol was ca. 3500 in spruce, lower in birch. Most of the β- and γ-positions in the side chains of C 9 units remained intact, except the coniferyl alcohol and aldehyde units. These structural features were constant during the reaction time up to 60min. It is concluded that the fragmentation of lignin in the phase-separative reaction system was principally due to the cleavage of benzyl aryl ethers, and the skeleton of lignocresol represents those of lignin subblocks formed by the dehydrogenative polymerization of monolignols.