Electrochemical Assembly for Synthesis of Middle-Sized Organic Molecules

Electrochemical methods offer a powerful, reliable, and environmentally benign approach for the synthesis of small organic molecules, and such methods are useful not only for the transformation of small molecules, but also for the preparation of oligomers and polymers. Electrochemical assembly is a concept that allows structurally well-defined middle-sized organic molecules to be synthesized by applying electrochemical methods. The preparation of dendrimers, dendronized polymers, and oligosaccharides are introduced as examples of such an approach. Automated electrochemical assembly of oligosaccharides is also demonstrated using the electrochemical synthesizer developed by our group

Electrochemical Glycosylation as an Enabling Tool for the Stereoselective Synthesis of Cyclic Oligosaccharides

Electrochemical glycosylation of a linear oligosaccharide with a protecting-group-free primary hydroxyl group afforded cyclic oligo-saccharides, up to hexasaccharides, in high yields. Precursors of the cyclic oligosaccharides were prepared by automated electro-chemical assembly-a method for the automated electrochemical solution-phase synthesis of oligosaccharides. We demonstrated that electrochemical glycosylation is useful not only for intermolecular glycosylation but also for intramolecular glycosylation to synthesize cyclic oligosaccharides

Electrochemical performance of Sn4P3 negative electrode for Na-ion batteries in ether-substituted ionic liquid electrolyte

We have previously disclosed that the ionic-liquid electrolyte sodium bis(fluorosulfonyl)amide (NaFSA)/1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)amide (Py13-FSA) can significantly improve the cycling stability of Sn4P3 negative electrodes for Na-ion batteries (NIBs). However, the strong electrostatic interaction between Na+ and FSA− in the electrolyte leads to high viscosity and low conductivity. In this study, we have tried to improve the conductivity of the electrolyte and enhance the rate capability of the Sn4P3 electrode by introducing an ether group in the side-chain of the ionic liquid cation to reduce said electrostatic interaction. Ether-substituted ionic liquid 1-methoxymethyl-1-methylpyrrolidinium (PyMOM)-FSA showed higher conductivity than Py13-FSA and the Sn4P3 electrode exhibited a higher rate capability. The differential capacity vs. potential plots suggest that the reaction between Na+ and Sn or P is promoted in the ether-substituted ionic liquid electrolyte. These results demonstrate that introduction of an ether moiety is an effective approach to improve the rate capability of the Sn4P3 electrode in NIBs

Effect of Annealing Temperature of Ni-P/Si on its Lithiation and Delithiation Properties

Annealed Ni–P–coated Si (Ni–P/Si) anodes for lithium-ion batteries have shown a superior cycle life with discharge capacity of 1000 mA h g−1 over 1100 cycles in some ionic-liquid electrolytes. However, the annealing temperature has yet to be optimized for Ni–P/Si electrodes. We investigated the electrochemical performance of Ni–P/Si electrode annealed at various temperatures in this study. The Ni–P/Si electrodes annealed at 800 ± 20 °C exhibited a superior cycle life with a reversible capacity of 1000 mA h g−1 over 1000 cycles, whereas the capacity of the electrodes annealed at temperatures of 750 °C and 850 °C faded at approximately 500 cycles. At 800 °C, a newly formed NiSi2 phase was theorized to significantly contribute to improving adhesion between the Ni–P coating layer and the Si particles. The Ni–P coating particles tended to aggregate at 850 °C, leading to a reduction in the coating effect, that is, a decline in their reactivity with Li+, acceleration of electrode disintegration, and a reduction in electrical conductivity. On the other hand, Ni–P/Si electrodes annealed at 850 °C exhibited a superior rate performance. The amount of available NiSi2 which ultimately contributed to higher reactivity with Li should increase

Piperidinium-Based Ionic Liquids as an Electrolyte Solvent for Li-Ion Batteries: Effect of Number and Position of Oxygen Atom in Cation Side Chain on Electrolyte Property

ArticleJournal of The Electrochemical Society. 167(7): 174101 (2019)journal articl

Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

The total synthesis of TMG-chitotriomycin using an automated electrochemical synthesizer for the assembly of carbohydrate building blocks is demonstrated. We have successfully prepared a precursor of TMG-chitotriomycin, which is a structurally-pure tetrasaccharide with typical protecting groups, through the methodology of automated electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block

Direct Extraction of Polysaccharides from Moso Bamboo (Phylostachys heterocycla) Chips Using a Mixed Solvent System of an Amino Acid Ionic Liquid with Polar Aprotic Solvent

The cellulose-dissolving ability and some physical properties of mixed solvents of an amino acid IL, N-methyl-N-(2-methoxyethyl)pyrolidin-1-ium 2,6-diaminohexanoate ([P1ME][Lys]), with polar aprotic solvents, such as 1,3-dimethylimidazolidinone (DMI), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and acetonitrile (CH3CN), have been investigated. The viscosity was significantly reduced by the increasing content of polar aprotic solvents, and a 1:1 mixture (molar ratio) of [P1ME][Lys] with DMF showed 91.5 cP which corresponded to less than 1/10 compared to that of the pure IL at 25 °C (1058 cP). The β values of the mixed solvents, which have the IL contents over 0.1, exhibited β-values similar to that of the pure IL. On the other hand, the π-value was dependent on the ratio of the IL content, and the pure IL had the highest π-value. We found that the mixed solvent of [P1ME][Lys] with DMF (1:1) easily dissolved the cellulose and the mixed solvent could be used to extract cellulose from moso bamboo (Phylostachys heterocycla) powder. The efficiency of the extraction of cellulose from the bamboo powder was significantly increased when a 1:1 mixture of the IL with a polar aprotic solvent was used as the extracting solvent at 60 °C; the extraction ratio of the 1:1 mixture (IL: DMF) reached twice that of the pure IL. We thus obtained cellulose in 18% (w/w) yield from the bamboo powder

Effect of Cation Structure of Ionic Liquids on Anode Properties of Si Electrodes for LIB

Ionic liquids consisted of 1-((2-methoxyethoxy)methyl)-1-methylpiperidinium (PP1MEM) or 1-hexyl-1-methylpiperidinium (PP16) and bis(trifluoromethanesulfonyl)amide (TFSA) were applied to an electrolyte for Li-ion battery. The effect of their cation structure on anode properties of Si electrodes were investigated through the use of thick film prepared by gas-deposition without any binder and conductive additive. The Si electrode in PP1MEM-TFSA exhibited an initial reversible capacity of 2670 mA h g−1, which is larger than that in PP16-TFSA by ca. 900 mA h g−1. Moreover, a comparatively high capacity of 1150 mA h g−1 at a high current density of 4200 mA g−1 is achieved in PP1MEM-TFSA whereas the Si electrode in PP16-TFSA showed the capacity of only 210 mA h g−1. Raman analysis and electrochemical impedance measurements revealed that PP1MEM cation played a role reducing the interaction between Li ion and TFSA anions, and that Li-ion transfer at the electrode−electrolyte interface in PP1MEM-TFSA was remarkably improved compared with PP16-TFSA. These results indicate that the excellent performances obtained in PP1MEM-TFSA originate from a smooth Li-insertion into Si electrode. It was suggested that introduction of ether functional group into cation is valid to enhance the electrode performance

Electrochemical Na-Insertion/Extraction Properties of Phosphorus Electrodes in Ionic Liquid Electrolytes

The electrochemical Na-insertion/extraction properties of phosphorus as a Na-ion battery anode in ionic liquid electrolytes were investigated by using a thick film without any binder or conductive additive. The ionic liquid with more electrochemically-stable cation structure, 1-((2-methoxyethoxy)methyl)-1-methylpyrrolidinium bis(fluorosulfonyl)amide (Py1MEM-FSA), delivered a high reversible capacity of 310 mA h g−1 at the 100th cycle, whereas the phosphorus electrode in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide (EMI-FSA) showed a low capacity of only 110 mA h g−1. It was revealed that disintegration of the electrode after cycling was effectively suppressed by applying Py1MEM-FSA instead of an organic electrolyte including propylene carbonate (PC), and that a surface layer induced by the decomposition of EMI-FSA hindered Na-insertion into the active material layer. The performance obtained in Py1MEM-FSA was very superior to that in PC. We applied for the first time a closed-system fire-resistance test to the ionic liquid electrolyte for quantitatively evaluating its non-flammability. The Py1MEM-FSA-based electrolyte exhibited an excellent fire resistance in comparison with the PC-based organic electrolyte, which can be an advantage for realizing a Na-ion battery with a high-energy density and a high safety