Thermoplasticization of wood. I. Benzylation of wood

A study of converting wood into thermoplastic materials was undertaken to develop a new technique in effective utilization of wood wastes. Thermoplasticizatoin of wood carried out by means benzylation. Various reaction parameters, such as alkalinity of reaction media, reaction temperature, and time were taken into account to produce benzylated wood with different degrees of substitution (based on weight gain) FTIR, DSC, DMTA, SEM and x-ray crystallography were used to characterize the chemical and mechanical properties of benzylated wood. Experimental data showed that preswelling and reaction temperature had critical effects on benzylation reaction. Lignin in wood appeared to inhibit benzylation but extractives had little effect. Different species showed some variation in reaction rates. The thermoplasticized wood exhibited good melting properties and were readily molded into bulk materials or extruded into films and sheets. A wide range of glass transition temperatures from 66 to 280°C for the benezylatedwoods was achieved, and they were larely dependent on the weight gain. The molded and extruded products exhibited acceptable mechanical strength for structural engineering applications. The property and structure relationship for the thermoplasticized wood were discussed     

Investigation by infrared absorption of the by-products of the cyanoethylation of cotton cellulose

The soluble cyanoethyl ether of cellulose, prepared by reaction in the presence of NaOH catalyst to high degrees of substitution (DS = 2.95), can be precipitated by various organic media and contains more nitrogen than can be accounted for by simple addition of acrylonitrile at each cellulose hydroxyl group. Infrared absorption spectra of such samples and of the reacted residues show various types of vibrational absorption bands, characteristic of amino groups. At advanced stages of the reaction the characteristic broad unresolved band of cellulose extending from 1200–950 cm.^?1 largely disappears, leaving only a few weaker bands which likely overlap those due to C–N stretching. Comparison is made of the spectra of the partially cyanoethylated cellulose and the polyacrylonitrile which forms in the stock acrylonitrile, to characterize the products. It is inferred that the highly cyanoethylated cellulose, partly dissolved in the acrylonitrile, further degrades and changes under a complex mechanism to various forms of amines. The yellow to orange color of the samples is assumed to be due to these by-products. The thermogravimetric analysis reveals that these products are more heat-resistant than the cyanoethylated cellulose.     

Cationic Xylan Derivatives with High Degree of Functionalization

Xylan from birch wood was characterized regarding both the supramolecular structure (X-ray, CP/MAS ¹³C-NMR) and the sugar composition. The reaction of the birch wood xylan with 2,3-epoxypropyltrimethylammonium chloride in 1,2-dimethoxyethane as slurry medium yields water-soluble, cationic 2-hydroxypropyltrimethylammonium xylan derivatives with high degree of substitution (DS). The DS values up to 1.6 can be controlled by adjusting the molar ratio in a one step synthesis. The structure of the cationic xylan derivatives was confirmed by means of DEPT(135) NMR spectroscopy. Film forming properties of cationic xylan derivatives were investigated with SEM measurements.     

Synthetic transformations of higher terpenoids: XXIV. Synthesis of cyanoethyl derivatives of lupane triterpenoids and their transformation into 1,2,4-oxadiazoles

Cyanoethylation of lupane triterpenoids was performed. Amide oximes of 3β-O-(2-cyanoethyl)-betulinic acid methyl ester and 3β-O-acetyl-28-O-(2-cyanoethyl)betulin and the corresponding O-[2-(1,2,4-oxadiazol-3-yl)ethyl] lupane derivatives were obtained.     

O2/CO2气氛下木醋调质石灰石直接硫化反应动力学研究

采用热分析法研究了O₂/CO₂气氛下石灰石及木醋调质石灰石的直接硫化反应过程。结果表明,在实验温度1 023~1 173 K,经木醋废液调质的石灰石直接硫化钙转化率显著提高。在1 173 K时,木醋调质石灰石直接硫化反应50 min后钙转化率可达89.55%。木醋调质石灰石的主要成分为水合醋酸钙,调质使石灰石的结构更为疏松,有利于硫化反应的进行。采用缩核模型对反应过程进行了表征,得到石灰石及木醋调质石灰石直接硫化反应速率常数k_s和扩散系数D_eff的Arrhenius表达式。动力学计算结果表明,相比于石灰石,扩散对木醋调质石灰石直接硫化反应过程的影响较小,说明木醋调质石灰石直接硫化反应性能显著提升的原因为硫化反应扩散阻力的减小。     

Development of a generalized phenomenological model describing the kinetics of the enzymatic hydrolysis of NaOH-treated pine wood

Pinus pinaster wood samples were treated during 3 h with alkaline solutions (containing 1, 5.5, or 10 weight percent NaOH) at 100, 115, or 130‡C using liquor/wood ratios of 6, 8, or 10 g/g. The solid residues obtained in treatments were used as substrates for enzymatic hydrolysis. In the hydrolysis assays, the reaction time (in the range 0–48 h) was considered as an operational variable. The cellulose conversion achieved at the end of assays were highest for samples pretreated at high temperature and high alkali concentration using low liquor/wood ratios. The experimental results obtained in each hydrolysis trial were fitted to an empirical model based on the assumption that the cellulose contained in substrates was composed by two fractions having different susceptibility to hydrolysis. The kinetic parameters obtained for the various experiments performed were correlated with the operational variables by means of empirical, statistically significant equations, which provided a generalized interpretation of the process.     

Thermogravimetric analysis and kinetics modeling of isothermal carbonization of olive wood in inert atmosphere

The kinetics of olive wood carbonization is investigated by means of isothermal thermogravimetric analysis method. Measurements were carried out in a thermobalance for different fixed temperatures between 498 and 648 K. A two-stage semi-global kinetic model consisting of four sequential steps was proposed to derive kinetic parameters. The olive wood is classified in three pseudo-components. For the first two, similar thermal degradation mechanisms take place in a single reaction step. For the third, the thermal degradation takes place in two consecutive steps. The isothermal conditions allow the kinetic constants (activation energy and pre-exponential factors) to be estimated by means of the analytical solution of the mass conservation equations. An overall good agreement was obtained with activation energy values available in the literature.     

4-(1,2-亚乙二氧基)环己酮及其2-甲醛和2-羧酸酯的烯胺和烯醇反应的研究

4-(1,2-亚乙二氧基)环己酮及其2-甲醛和2-羧酸酯的烯胺和烯醇与丙烯酸型的和丙二酸型的试剂反应,获得了与6-(1,2-亚乙二氧基)-5,6,7,8-四氢-2(1H)- 喹啉酮很相近的四个化合物(5,11,18,19)和六个其它化合物(4,7,8,9,16,17).探讨了这十个均未见于文献的新化合物的生成机理,并得到一个制备5- 四氢萘胺衍生物的新方法     

Evaluation of processing temperature in the production of fibre reinforced epoxy composites

A group of cyanoethylated amine (CEA) has been synthesized by carefully reacting triethylenetetramine with varying proportions of acrylonitrile. Such CEAs were utilized as hardener for the curing of epoxy resin. The effect of cyanoethylation of amine on their curing reaction with epoxy resin has been studied by differential scanning calorimeter (DSC). The processing temperature for the fabrication of composite is estimated from the DSC analysis with an approach to satisfy the logical selection of temperature for application of pressure during processing of a composite structure. The exotherm of such curing reaction (?H _ex) and the degree of cyanoethylation (CEt) of the amine follow the relation ?H _ex ?=?(324?C68.40?CEt)?J?g^?1.     

Cyanoethylation of substituted 4-azafluorenes. Synthesis of spiro-[4-azafluorene-9-cyclopentenes]

Cyanoethylation of 9-phenacyl(β-hydroxy-β-phenylethyl-, or acetamido)-4-azafluorenes under conditions of the Michael reaction occurs regioselectively at position 9. 1-Amino-4-azafluorene under these conditions forms 1-[N,N-di-(β-cyanoethyl)amino)]-(9-β-cyanoethyl)-4-azafluorene. The cyclization of 9-(β-cyanoethyl)-9-phenacyl-4-azafluorene has been carried out into 1′-cyano-2′-phenylspiro[4-aza-fluorene-9,4′-cyclopentene and 1′-imino-2′-hydroxybenzylidenespiro[4-azafluorene-9.3′-cyclopentane]-substituted in the five-membered fragment. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1496–1501, October, 2006.     

Cyanoethylation of azafluorenes and syntheses of alcohols containing an azafluorene fragment

Isomeric (with respect to the position of the nitrogen atom) azafluorenes were cyanoethylated. The resulting 9,9-bis(-cyanoethyl) derivatives were converted to the corresponding dibasic acids and their diesters. The latter were subjected to the Dieckmann reaction to obtain spiro compounds with azafluorene and cyclohexene fragments. The analogous spirans with 1,3-dioxalane and 1,3-dioxane rings were obtained from 3-methyl-2-azafluorenone.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1668–1672, December, 1982.     

s-Triazines

The reaction of tetrafluoroethylene, trifluorochloroethylene, and perfluoropropene with methyl-, ethyl-, cyclo- hexyl- and allylguanidines in dimethylformamide is investigated, and is shown to give N-monoalkyl-substituted guanamines containing CF₂H, CFClH, and CF₃CFH radicals, and hydrofluorides of alkylguanidines and alkylamines. A mechanism for the reaction is proposed. To confirm the structures of the guanamines, IR spectra of the most important compounds are given. Cyanoethylation and chlorination of some guanamines are investigated. For Part V see [1]     

杂环-双氰乙基系列分散染料的合成、表征及染色性能

以4个杂环芳香胺为重氮组分, 3个N,N-二氰乙基芳香胺为偶合组分, 经重氮化、 偶合反应合成了12个杂环-双氰乙基系列偶氮物; 采用紫外-可见吸收光谱、 红外光谱及核磁共振氢谱等对其结构进行了表征; 还考察了它们在涤纶织物、 乙酰化杉改性木粉和氰乙基化改性木粉上的染色性能. 结果表明, 12个偶氮物为目标产物, 在N,N-二甲基甲酰胺(DMF)中的最大可见吸收波长为417～621 nm, 摩尔吸光系数均大于10⁴. 这些化合物染色涤纶织物的色光分属黄色、 红色、 紫红色和蓝色系列, 并具有高水洗牢度和高日晒牢度; 染色乙酰化木粉和氰乙基木粉的色光和水洗牢度与染色涤纶织物相近. 这12个分散染料具有色谱范围广、 色泽鲜艳、 高发色强度和高牢度等特点, 可用于多种纤维的染色.     

Characterization of waterlogged wood by NMR and GPC techniques

Anaerobic erosion bacteria can slowly degrade waterlogged wood, causing a loss of cellulose and hemicellulose. During this process, lignin can also be altered. For this reason, the chemical characterization of waterlogged archaeological wood is crucial for both the elucidation of the degradation processes and also the development of consolidation and conservation procedures.The complex structure of wood makes it practically impossible to dissolve wood in its native form in conventional molecular solvents. Ionic liquids can provide a homogeneous reaction medium for wood-based lignocellulosic materials. Highly substituted lignocellulosic esters and phosphite esters can be obtained under mild conditions by reacting pulverized wood dissolved in ionic liquid with either acyl chlorides or dioxaphospholanes in the presence of pyridine. As a result, the functionalized wood develops an enhanced solubility in molecular solvents, allowing for a complete characterization by means of spectroscopic and chromatographic techniques.In this study, archaeological woods and reference sound woods of the same taxa (Quercus and Arbutus unedo), along with the corresponding extracted lignin, were fully characterized by means of phosphorus NMR spectroscopy, two dimensional NMR spectroscopy and GPC analysis. The samples were collected from the Site of the Ancient Ships of San Rossore (Pisa, Italy), where many shipwrecks dating from 2nd century BC to 5th century AD have been discovered.The results highlighted a deeper and faster depolymerization of the polysaccharide matrix against a limited degradation of the lignin fraction. The use of innovative solvent system as the ionic liquid [amim]Cl enables to highlight chemical and morphologic changes in wood composition avoiding further degradation.     

Differential scanning calorimetry of hydrogen peroxide and hydrogen peroxide-treated lignocellulose. I. Ambient pressure conditions

The decomposition reaction of aqueous solutions of hydrogen peroxide was examined by DSC at ambient pressure, and the heat of evaporation of H₂O₂ was determined. The reaction parameters for the oxidation reaction of lignocellulose (wood powder) with hydrogen peroxide were also examined. The pans made from gold and alodined (pyrophosphate /fluoride treated) aluminum were unsuitable for the work due to surface catalysis, in contrast to pure aluminum which proved to be acceptable within the temperature range examined. In pans made from pure aluminum, the reaction between lignocellulose and hydrogen peroxide takes place after the latter evaporates, i.e. it represents a gas—solid reaction.     

Antikonvulsiva,II. Die cyanethylierung im system des butyroguanamins

The cyanoethylation of butyroguanamine ( 1 ) comprising the addition of acrylonitrile ( 2 ) leads to the cyanoethylated propyl-1,3,5-triazines 3, 4 , and 5 . The sharp band of the C ≡ N stretching vibrations at 2260 cm^?1 in their spectra is very characteristic for these structures. In the mass spectra, cleavage of a cyanoethyl radical is shown to be a marked degradation path. While 4 is capable of producing anticonvulsive and cytoprotective effects, 5 exhibits neuroleptic and herbicidal activity.     

Co-firing of biomass with coals

The chemical composition and reactivity of fir (Abies bornmulleriana) wood under non-isothermal thermogravimetric (TG) conditions were studied. Oxidation of the wood sample at temperatures near 600 °C caused the loss of aliphatics from the structure of the wood and created a char heavily containing C–O functionalities and of highly aromatic character. On-line FTIR recordings of the combustion of wood indicated the oxidation of carbonaceous and hydrogen content of the wood and release of some hydrocarbons due to pyrolysis reactions that occurred during combustion of the wood. TG analysis was used to study combustion of fir wood. Non-isothermal TG data were used to evaluate the kinetics of the combustion of this carbonaceous material. The article reports application of Ozawa–Flynn–Wall model to deal with non-isothermal TG data for the evaluation of the activation energy corresponding to the combustion of the fir wood. The average activation energy related to fir wood combustion was 128.9 kJ/mol, and the average reaction order for the combustion of wood was calculated as 0.30.     

Catalyzed steam gasification of biomass

Steam gasification of wood in the presence of catalysis was investigated. Two methods for wood/catalyst contacting were used: dry mixing of the wood and solid catalyst and impregnation of the wood with catalyst. Impregnation gave greater yields and rates than dry mixing and was used throughout the remainder of the investigation.Catalysts used included potassium carbonate, sodium carbonate, trona, and borax, in order of their effectiveness at all temperatures.The gasification process with and without catalyst occurred in two stages: (1) a rapid pyrolysis immediately after heatup and (2) reaction of steam with the char residue. The steam/char reaction obeyed pseudo-first-order kinetics.     

Cyanoethylation of pyrazoles under conditions of phase-transfer catalysis and hydrogenation of the cyanoethylation products

Cyanoethylation of pyrazoles with acrylonitrile was studied under conditions of phase-transfer catalysis. The ease of the process depends on the acidity of pyrazoles. Cyanoethylpyrazoles can be converted into the corresponding aminopropylpyrazoles via reduction of the cyano group. The reduction with lithium tetrahydridoaluminate is accompanied by β-elimination of the cyanoethyl group.     

Acid Hydrolysis of Hemicellulose in Green Liquor Pre-Pulping Extract of Mixed Northern Hardwoods

Forest biomass is a promising resource for future biofuels and bioproducts. Pre-pulping extraction of hemicellulose by alkaline (Green Liquor) pretreatment produces a neutral-pH extract containing hemicellulose-derived oligomers. A near-term option for use of this extract is to hydrolyze the oligomers to fermentable monomer sugars. Chips of mixed northern hardwoods were cooked in a rocking digester at 160 °C for 110 min in Green Liquor at a concentration of 3% Na₂O equivalent salts on dry wood. The mass of wood extracted into the Green Liquor extract was approximately 11.4% of the debarked wood mass, which resulted in a dilute solution of oligomeric hemicelluloses sugars. The concentration of the extract was increased through partial evaporation prior to hydrolysis. Dilute sulfuric acid hydrolysis was applied at conditions ranging from 100 to 160 °C, 2% to 6% (w/v) H₂SO₄, and 2- to 258-min residence time. The maximum fermentable sugar concentration achieved from evaporated extract was 10.7 g/L, representing 90.7% of the maximum possible yield. Application of the biomass pretreatment severity function to the hydrolysis results proved to offer a relatively poor prediction of temperature and reaction time interaction. The combined severity function, which incorporates reaction time, temperature, and acid concentration, did prove to provide a useful means of trading off the combined effects of these three variables on total sugar yields.