SYNTHESES WITH DIKETO SELENIDES

Abstract

We report a) a modified synthesis of diketo selenides, b) preparation of 2,5-diacylselenophenes by condensation of diketo selenides with glyoxal, c) preparation of poly-substituted selenophenes by intramolecular reductive coupling reaction of diketo selenides with low-valent titanium reagent under controlled conditions (0°C) followed by dehyration of the resulting 3,4-dihydroxyselenolanes, and d) formation of 2,5-dihydroselenophenes and 1,3-dienes by treatment of diketo selenides with the low-valent titanium reagent in refluxing tetrahydrofuran.     

Ab initio prediction for the ionic conduction of lithium in LiInSiO4 and LiInGeO4 olivine materials

In this paper, olivine-type LiInSiO₄ and LiInGeO₄ as fast ionic conductors are predicted by ab initio density functional studies. The nudged elastic band approach showed extremely small energy barrier for lithium ion hopping to neighboring sites with 0.23 eV for LiInGeO₄ and 0.36 eV for LiInSiO₄. However, formation energy for the intrinsic defects including lithium ion vacancy sites is expected to be large (more than ～1.5 eV), which suppresses ionic conductivity severely. Therefore it is expected that doping these olivine-type materials with higher valent cations may be a better option to create lithium ion vacancies.     

Wavelet‐based data compression for flow simulation on block‐structured Cartesian mesh

A data compression method based on image encoding techniques is presented for a flow simulation data set. An input flow field data set is converted into the octree structure by discrete wavelet transform, and then quantized finely or coarsely depending on its importance in the flow field. Embedded zerotree wavelet encoding as the image encoding technique and entropy encoding reduce the data size by making use of the octree structure created previously. The present compression method is incorporated in a block‐structured Cartesian mesh method called Building‐Cube method. The Building‐Cube method gives not only good performance in the flow simulation but also consistency with the embedded zerotree wavelet encoding in the data compression. Three compression cases for incompressible and compressible flow simulations, including a large‐scale simulation with O(10 ⁸) mesh points, demonstrate that the present compression method gives both high compression ratios and good qualities of compressed data. Copyright © 2013 John Wiley & Sons, Ltd.     

One-Step Synthesis of 1,3-Bis(carboxymethyl) Adamantane

Addition of the carbonium ion to vinylidene chloride to give α-substituted acetic acid discovered by Bott^1,2 has been found of wide applicability. For example, the reaction of 1-bromo-, 1-hydroxy-, or 1-acetoxy-adamantane with vinylidene chloride in concentrated sulfuric acid gives a satisfactory yield of adamanty1-(1)-Acetic acid.^3,4     

Synthesis and biodegradation of poly(2-pyrrolidone-co-ε-caprolactone)s

Copolyesteramides of 2-pyrrolidone with ε-caprolactone were synthesized by ring-opening copolymerization. The copolymers were random-like and their melting temperature and heat of fusion were dependent on the polymer composition. Biodegradation by a polyamide 4 (PA4) degrading microorganism showed rapid degradation in the region of amide-rich polymer composition. On the contrary, enzymatic hydrolysis using a lipase resulted in a different tendency, that is, ester-rich copolymers hydrolyzed rapidly. Activated sludge makes copolymers degrade to CO₂ in wide polymer composition ratio. Copolyesteramides are expected to be applied as an environmentally-friendly plastics or bioabsorbable polymers in medical fields.