Efficient hydrolysis of polysaccharides in bagasse by in situ synthesis of an acidic ionic liquid after pretreatment

A highly efficient hydrolytic method using an acidic ionic liquid is proposed: pretreatment of biomass with H2SO4; simple in situ synthesis of an acidic ionic liquid, 1-(1-butylsulfonic)-3-methylimidazolium hydrosulfate ([(HSO3)4C4C1im]HSO4), through addition of a zwitterion to the pretreated solution; and subsequent hydrolysis in the [(HSO3)4C4C1im]HSO4 solution at 100 °C under microwave heating. The high yields of glucose and xylose (around 80 and 100%, respectively) were attributed to the pretreatment by H2SO4 and the efficient catalytic activity of the [(HSO3)4C4C1im]HSO4. The high yields were comparable to the highest yields of acid hydrolysis at around 100 °C among previous literature, and the present method achieved more rapid hydrolysis. Decomposition of glucose and xylose was negligible because the reaction temperature was relatively mild. We also identified an electrodialysis method to separate [(HSO3)4C4C1im]HSO4 into H2SO4 and the zwitterion for reuse. Almost all of the H2SO4 (97%) was transferred to the concentrate compartment, and 99% of the zwitterion remained in the dilute compartment during electrodialysis.Embargo Perid 12 months / Published online 24 October 201

Structure and dynamics of room temperature ionic liquids with bromide anion: Results from 81Br NMR spectroscopy

We report the results of a comprehensive 81Br NMR spectroscopic study of the structure and dynamics of two room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium bromide ([C4mim]Br) and 1-butyl-2,3-dimethylimidazolium bromide ([C4C1mim]Br), in both liquid and crystalline states. NMR parameters in the gas phase are also simulated for stable ion pairs using quantum chemical calculations. The combination of 81Br spin-lattice and spin-spin relaxation measurements in the motionally narrowed region of the stable liquid state provides information on the correlation time of the translational motion of the cation. 81Br quadrupolar coupling constants (CQ) of the two RTILs were estimated to be 6.22 and 6.52 MHz in the crystalline state which were reduced by nearly 50% in the liquid state, although in the gas phase, the values are higher and span the range of 7-53 MHz depending on ion pair structure. The CQ can be correlated with the distance between the cation-anion pairs in all the three states. The 81Br CQ values of the bromide anion in the liquid state indicate the presence of some structural order in these RTILs, the degree of which decreases with increasing temperature. On the other hand, the ionicity of these RTILs is estimated from the combined knowledge of the isotropic chemical shift and the appropriate mean energy of the excited state. [C4C1mim]Br has higher ionicity than [C4mim]Br in the gas phase, while the situation is reverse for the liquid and the crystalline states. Copyright © 2015 John Wiley & Sons, Ltd

Structural characterization of the body frame and spicules of a glass sponge

金沢大学理工研究域自然システムThe nanostructure (atomic-scale structure) and water species in the body frame and spicules of the marine glass sponge, Euplectella aspergillum, collected from the sea floor around Cebu Island was characterized in detail by thermogravimetric differential thermal analysis, nuclear magnetic resonance spectroscopy, Raman and infrared spectroscopies, and X-ray diffraction method. The structural features of the nanostructure in the body frame and spicules were essentially similar to each other, although these were different from those of inorganic amorphous silica materials, such as silica gel and silica glass. In addition, the averaged short and medium range structures of the sponge may be similar to those of tridymite. The water content and water species included in the body frame and spicules were almost the same. More than half of the contained water was physisorbed water molecules, and the rest was attributed to Q3 and Q2 silanol groups. Most of the water species may be present at the surface and involved in hydrogen bonding

Structural analysis of crystalline R(+)-α-lipoic acid-α-cyclodextrin complex based on microscopic and spectroscopic studies

R(+)-α-lipoic acid (RALA) is a naturally-occurring substance, and its protein-bound form plays significant role in the energy metabolism in the mitochondria. RALA is vulnerable to a variety of physical stimuli, including heat and UV light, which prompted us to study the stability of its complexes with cyclodextrins (CDs). In this study, we have prepared and purified a crystalline RALA-αCD complex and evaluated its properties in the solid state. The results of 1H NMR and PXRD analyses indicated that the crystalline RALA-αCD complex is a channel type complex with a molar ratio of 2:3 (RALA:α-CD). Attenuated total reflection/Fourier transform infrared analysis of the complex showed the shift of the C=O stretching vibration of RALA due to the formation of the RALA-αCD complex. Raman spectroscopic analysis revealed the significant weakness of the S–S and C–S stretching vibrations of RALA in the RALA-αCD complex implying that the dithiolane ring of RALA is almost enclosed in glucose ring of α-CD. Extent of this effect was dependent on the direction of the excitation laser to the hexagonal morphology of the crystal. Solid-state NMR analysis allowed for the chemical shift of the C=O peak to be precisely determined. These results suggested that RALA was positioned in the α-CD cavity with its 1,2-dithiolane ring orientated perpendicular to the plane of the α-CD ring. © 2015 by the authors; licensee MDPI, Basel, Switzerland

Flame-retardant thermoplastics derived from plant cell wall polymers by single ionic liquid substitution

金沢大学理工研究域生命理工学系Three components of plant cell walls—cellulose, hemicellulose and lignin—were converted into flame-retardant thermoplastics by adducting only a single ionic liquid species via covalent bonds. They showed thermoplasticity and formed thin films by hot pressing. They also showed flame retardancy and self-extinguished the fire during burning. The properties of the samples depend on the cation species of ionic liquids adducted and thus are controllable. In the present study, more than 66% of the hydroxyl groups present on the polymers were maintained after derivatisation; they thus have the potential for further functionalisation for moulding, practical use and so on, in addition to flame retardancy and thermoplasticity.Embargo Period 12 monthsThis paper has supplementary information

Nano-Structural Investigation on Cellulose Highly Dissolved in Ionic Liquid: A Small Angle X-ray Scattering Study

We investigated nano-structural changes of cellulose dissolved in 1-ethyl-3-methylimidazolium acetate—an ionic liquid (IL)—using a small angle X-ray scattering (SAXS) technique over the entire concentration range (0–100 mol %). Fibril structures of cellulose disappeared at 40 mol % of cellulose, which is a significantly higher concentration than the maximum concentration of dissolution (24–28 mol %) previously determined in this IL. This behavior is explained by the presence of the anion bridging, whereby an anion prefers to interact with multiple OH groups of different cellulose molecules at high concentrations, discovered in our recent work. Furthermore, we observed the emergence of two aggregated nano-structures in the concentration range of 30–80 mol %. The diameter of one structure was 12–20 nm, dependent on concentration, which is ascribed to cellulose chain entanglement. In contrast, the other with 4.1 nm diameter exhibited concentration independence and is reminiscent of a cellulose microfibril, reflecting the occurrence of nanofibrillation. These results contribute to an understanding of the dissolution mechanism of cellulose in ILs. Finally, we unexpectedly proposed a novel cellulose/IL composite: the cellulose/IL mixtures of 30–50 mol % that possess liquid crystallinity are sufficiently hard to be moldable

Ionic Dynamics in [C₄mim]NTf₂ in the Glassy and Liquid States: Results from ¹³C and ¹H NMR Spectroscopy

The ionic dynamics of the room temperature ionic liquid 1-butyl-3-methylimdiazolium bis­((trifluoromethyl)­sulfonyl)­amide ([C₄mim]­NTf₂) is studied using ¹³C and ¹H nuclear magnetic resonance (NMR) spectroscopy over a wide temperature range encompassing the glassy and liquid states. The temperature dependence of the ¹³C spin–lattice relaxation time is analyzed with four different models to derive the rotational dynamics of the RTIL in the nano to picosecond range. It was found that the extended model-free approach bridges the data obtained from the BPP and DC models, and describes ion dynamics of the RTIL well. Three different motions are observed based on the approach: an overall ion rotation, a slow and a fast local rotational motion. The time scale of the slow local rotational motion, particularly of the imidazolium ring carbons, is strongly coupled to the time scale of the overall ion rotation, above the melting point. Below the melting point these two time scales show strong decoupling and the local rotation displays nanosecond dynamics in the glassy state. The analyses of the second moment (<i>M</i>₂) of the ¹H and ¹³C nuclides indicate that, in addition to the axial rotations of the two methyl groups (cation) and the CF₃ group (anion), all ¹³C sites including the imidazolium ring carbon and CF₃ show evidence of mobility, even in the glassy state

Nano-Structural Investigation on Cellulose Highly Dissolved in Ionic Liquid: A Small Angle X-ray Scattering Study

We investigated nano-structural changes of cellulose dissolved in 1-ethyl-3-methylimidazolium acetate—an ionic liquid (IL)—using a small angle X-ray scattering (SAXS) technique over the entire concentration range (0–100 mol %). Fibril structures of cellulose disappeared at 40 mol % of cellulose, which is a significantly higher concentration than the maximum concentration of dissolution (24–28 mol %) previously determined in this IL. This behavior is explained by the presence of the anion bridging, whereby an anion prefers to interact with multiple OH groups of different cellulose molecules at high concentrations, discovered in our recent work. Furthermore, we observed the emergence of two aggregated nano-structures in the concentration range of 30–80 mol %. The diameter of one structure was 12–20 nm, dependent on concentration, which is ascribed to cellulose chain entanglement. In contrast, the other with 4.1 nm diameter exhibited concentration independence and is reminiscent of a cellulose microfibril, reflecting the occurrence of nanofibrillation. These results contribute to an understanding of the dissolution mechanism of cellulose in ILs. Finally, we unexpectedly proposed a novel cellulose/IL composite: the cellulose/IL mixtures of 30–50 mol % that possess liquid crystallinity are sufficiently hard to be moldable

Structural Characterization of the Body Frame and Spicules of a Glass Sponge

The nanostructure (atomic-scale structure) and water species in the body frame and spicules of the marine glass sponge, Euplectella aspergillum, collected from the sea floor around Cebu Island was characterized in detail by thermogravimetric differential thermal analysis, nuclear magnetic resonance spectroscopy, Raman and infrared spectroscopies, and X-ray diffraction method. The structural features of the nanostructure in the body frame and spicules were essentially similar to each other, although these were different from those of inorganic amorphous silica materials, such as silica gel and silica glass. In addition, the averaged short and medium range structures of the sponge may be similar to those of tridymite. The water content and water species included in the body frame and spicules were almost the same. More than half of the contained water was physisorbed water molecules, and the rest was attributed to Q3 and Q2 silanol groups. Most of the water species may be present at the surface and involved in hydrogen bonding