The Role of Green Chemistry in Biomass Processing and Conversion

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Mechanical and Electrical Properties of Y-containing Al-Zr Heat-resistant Alloy Produced by Dynamic ECAE Process

The influence of rare earth Y on the microstructure and mechanical properties of Al-Zr alloy produced by dynamic ECAE was studied by OLYMPUS-BX51M optical microscope (OM), S4800 energy disperse spectroscopy (EDS) and SANS CMT5105 electronic universal material testing machine, and the corresponding equivalent conductivity was also investigated by using QJ48 DC electric bridge. The results show that the tensile strength of Al-Zr conductor first increases and then decreases with the increase of the aging time and temperature, and the highest tensile value can be obtained under the aging temperature of 160 °C for 4 h. The ductility and the resistivity of the Al-Zr alloy have inverse proportion to the aging time. The rare earth Y has significantly improved the electrical and mechanical properties of Al-0.3%Zr heat-resistant alloy. In this study, the tensile strength and the elongation of the Al-0.3%Zr-0.2%Y alloy, after aging treatment at 220 °C for 14 h, are about 278.49 MPa and 6.7%, respectively, and the equivalent conductivity is about 59.6 IACS. Hence the synthetical properties of the Y-containing alloy are significantly improved compared with traditional Al-0.3%Zr alloy

Catalysis of Reactions by Amino Acids

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Biorefinery with Ionic Liquids

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Biorefinery with Ionic Liquids

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A General and Straightforward Method for the Synthesis of 2-Trifluoromethylbenzothiazoles

An efficient one-pot method for the synthesis of 2-trifluoromethylbenzothiazoles by the treatment of trifluoromethylimidoyl chlorides with sodium hydrosulfide hydrate using PdCl2 as the sole catalyst in DMSO is described. The reaction proceeds via thiolation/C−H bond functionalization/C−S bond formation in moderate to high yields with good functional group tolerance

Introducing the Reversible Reaction of CO₂ with Diamines into Nonisocyanate Polyurethane Synthesis

Nonisocyanate polyurethanes (NIPUs) are considered greener alternatives to traditional polyurethanes, and the preparation of NIPUs considerably depends on the design and synthesis of suitable monomers. Herein, we propose a toolbox for in situ capturing and conversion of CO2 into α,ω-diene-functionalized carbamate monomers by taking advantage of the facile reversible reaction of CO2 with diamines in the presence of organic superbases. The activation of CO2 into carbamate intermedia was demonstrated by NMR and in situ FTIR, and the optimal conditions to prepare α,ω-diene-functionalized carbamate monomers were established. Thiol–ene and acyclic diene metathesis (ADMET) polymerization of these monomers under mild conditions yielded a series of poly(thioether urethane)s and unsaturated aromatic–aliphatic polyurethanes with high yield and glass transition temperatures ranging from −26.8 to −1.1 °C. These obtained NIPUs could be further modified via postpolymerization oxidation or hydrogenation to yield poly(sulfone urethane) and saturated polyurethane with tunable properties

Brønsted Guanidine Acid−Base Ionic Liquids: Novel Reaction Media for the Palladium-Catalyzed Heck Reaction

Brønsted acid−base ionic liquids (GILs) based on guanidine and acetic acid are efficient reaction media for palladium-catalyzed Heck reactions. They offer the advantages of high activity and reusability. GIL2 plays multiple roles in the reaction:  it could act as solvent, as a strong base to facilitate β-hydride elimination, and as a ligand to stabilize activated Pd species

Thorough Chemical Modification of Wood-Based Lignocellulosic Materials in Ionic Liquids

Homogenous acylation and carbanilation reactions of wood-based lignocellulosic materials have been investigated in ionic liquids. We have found that highly substituted lignocellulosic esters can be obtained under mild conditions (2 h, 70 °C) by reacting wood dissolved in ionic liquids with acetyl chloride, benzoyl chloride, and acetic anhydride in the presence of pyridine. In the absence of pyridine, extensive degradation of the wood components was found to occur. Highly substituted carbanilated lignocellulosic material was also obtained in the absence of base in ionic liquid. These chemical modifications were confirmed by infrared spectroscopy, 1H NMR, and quantitative 31P NMR of the resulting derivatives. The latter technique permitted the degrees of substitution to be determined, which were found to vary between 81% and 95% for acetylation, benzoylation, and carbanilation, accompanied by similarly high gains in weight percent values. Thermogravimetric measurements showed that the resulting materials exhibit different thermal stabilities from those of the starting wood, while differential scanning calorimetry showed discrete new thermal transitions for these derivatives. Scanning electron microscopy showed the complete absence of fibrous characteristics for these derivatives, but instead, a homogeneous porous, powdery appearance was apparent. A number of our reactions were also carried out in completely recycled ionic liquids, verifying their utility for potential applications beyond the laboratory bench

Diastereoselective Silver-Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with Fluorinated Imine

We described hereby an instance of diastereoselective silver-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with imine compounds. This new method provided synthetically useful, highly substituted tetrahydroimidazole derivatives with efficiency and high diastereoselectivity. We can conveniently obtain fluorinated dihydroimidazole, imidazole, and diamino esters through simple modification