Shuji Hosoya

A Characteristic Reaction of Lignin in Ionic Liquids; Glycelol Type Enol-Ether as the Primary Decomposition Product of β-O-4 Model Compound

Abstract Guaiacylglycerol-β-guaiacyl ether (GG), which contains a predominant inter-unit linkage of lignin, could be converted into a corresponding glycerol type enol-ether (EE), 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-2-propenol, by the heat treatment in ionic liquids. EE is believed to be the unstable intermediate of the lignin decomposition process under acidic and alkaline conditions. By contrast, EE could be isolated as a relatively stable compound from the reaction mixture of ionic liquids. EE was formed as a primary reaction product in all ionic liquids used in this research under the temperature conditions of 120°C, although the decomposition rate and secondary decomposition products of GG varied with the ionic liquid used. NMR data suggested that dehydration reaction of GG progressed stereospecifically and [Z] isomer was predominantly formed (stereoselectivety of [Z] is higher than 90%).

Degradation of Lignin with Ozone: Reactivity of Lignin Model Compounds Toward Ozone

Abstract In order to elucidate the reactivities of different types of lignin-structural units toward ozone, various lignin model compounds were ozonized. The results obtained are summarized as follows: 1) An α-carbonyl type structure is much more stable against ozone than a benzyl alcohol type structure. 2) A guaiacyl nucleus reacts faster with ozone than a vera try 1 one. 3) Biphenyl and phenylcoumaran structures react readily with ozone. However, a biphenyl structure of veratryl nuclei is very stable against ozone. 4) From the results of molecular orbital calculations, Pz orbitals (LUMO) of ozone form bonding orbitals to those (HOMO) of lignin aromatic nucleus at C3 and C4 positions. Furthermore, the squares of LCAO coefficients of C3 and C4 positions are greater than those of other positions in Pz orbital (HOMO) of lignin aromatic nucleus. This suggests that ozone reacts selectively with the lignin aromatic nucleus at C3-C4 position.

Ozone pretreatment of lignocellulosic materials for ethanol production: Improvement of enzymatic susceptibility of softwood

Abstract In order to utilize lignocellulosic biomass as a feedstock for bioethanol, ozone pretreatment was conducted on Japanese cedar sawdust and three other lignocellulosic wastes. Successful lignin degradation was accomplished by ozone pretreatment of the Japanese cedar sawdust and over 90% of polysaccharides were converted to monomeric sugars by enzymatic saccharification. This ozone pretreatment was also effective with other lignocellulosics, such as Hinoki cypress sawdust, lumber and board wastes. Ethanol production by simultaneous saccharification and fermentation of the ozone pretreated Japanese cedar sawdust was also successful. It was shown that ozone pretreatment increases enzymatic susceptibility and enables the production of ethanol from lignocellulosic biomass.

Possibilities of the Formation of Enol-Ethers in Lignin by Soda Pulping

In the alkaline decomposition of a β-O-4 type lignin model compound (erythro-guaiacylglycerol-β-guaiacyl ether, compound 1), an isomeric pair of C6C2 enol-ether (2-methoxy-4-[2-(2-methoxyphenoxy)-vinyl]-phenol, compound 2) was detected as the main decomposition product with no trace of C6C3 enol-ether (4-[3-hydroxy-1-(2-methoxyphenoxy)-propenyl]-2-methoxy-phenol, compound 3) or other dimers. In contrast, compound 2 was not detected in the alkaline decomposition products of compound 3. Under alkaline conditions, the γ-hydroxymethyl group of compound 3 was reduced to form 2-methoxy-4-[1-(2-methoxyphenoxy)-propenyl]-phenol (compound 4). In the HSQC analysis of soda lignin, the formation of substructures of C6C2 type enol-ether (related to compound 2) was confirmed. However, no substructures related to compound 4, which could be formed if a substructure of C6C3 type enol-ether was formed under alkaline conditions, were detected. Therefore, it could be concluded that C6C3 type enol-ethers could not be intermediates of alkaline decomposition products of lignin.

Effect of ozonation on composting Japanese cedar wood meal

Abstract Ozonized Japanese cedar wood meal was evaluated as a feedstock for compost. The composting experiment performed in a 1.8 m3 tank during a 4-week period showed that the decomposition of organics was accelerated by the ozonation of wood meal during thermophilic phase. The same is true for decay test of white-rot (WR) fungus. The tested brown-rot (BR) fungus did not show any effect. Accordingly, the lignin degradation by ozone is advantageous for composting. In addition, liberation of ammonia, one source of odor development, was suppressed during the thermophilic phase of composting of ozonized wood meal.

Performance of Softwood Soda-Anthraquinone Lignin–Polyethylene Glycol Derivatives as Water-Reducing Admixture for Concrete

We have developed a high-performance lignin-based water-reducing admixture. In this study, softwood soda-anthraquinone lignin was modified with mono-epoxide polyethylene glycols having chain lengths of 10, 25, and 50 mol (the number of repeating units of ethylene oxide). The mortar flow and concrete slump flow tests were used to investigate the performance of the lignin derivatives as a water-reducing admixture. All tested lignin-PEG derivatives performed considerably better than a commercial lignosulfonate water-reducing admixture in the mortar flow test. In particular, the derivative with a PEG chain length of 50 mol performed excellently in both tests. The optimum PEG content for mortar dispersion was approximately 40% for lignin derivatives with a PEG chain length of 50 mol; this content exhibited a dispersing effect that was four times higher than that of the lignosulfonate water-reducing admixture. The strength of concrete containing the lignin derivatives was almost the same strength as that of concrete containing the commercial lignosulfonate water-reducing admixture.

Reduction of chloroform emission from hypochlorite-bleaching process

Chloroform was readily converted to formic acid through the nucleophilic attack of hydroxyl anion under the certain reaction conditions (pH>12, temp.>70°C). When guaiacol was reacted with hypochlorite at such reaction conditions, the generation of chloroform was almost completely reduced. Successful reduction of the chloroform generation was also observed in alkaline hypochlorite bleaching of kraft pulps and DIP without any loss in pulp quality.Even when the hypochlorite bleaching was carried out under the open system (no sealing of the reaction vessel). nearly 90% of the generated chloroform was converted to formic acid.