EXTRACTION ENHANCEMENT OF TITANIUM(IV) ACETYLACETONATE IN THE PRESENCE OF PHENOLS

ABSTRACT

The effects of phenols as additives on the solvent extraction of titanium(IV) with acetylacetone in carbon tetrachloride have been investigated. Titanium(IV) is scarcely extracted with acetylacetone, and the extractability is lower than that of the other titanium group metals, zirconium(IV) and hafnium(IV). However, the extractability of titanium(IV) acety lacetonate is greatly enhanced in the presence of 3,5-dichlorophenol where titanium(IV) can be extracted quantitatively and better than zirconium(IV) or hafnium(IV). The effects of the phenols (3,5-dichlorophenol, 3,5-dimethylphenol, and 4-chlorophenol) are greater than that of benzoic acid, and the phenol with the lower pK_a value is more effective. From equilibrium analy sis on the extraction system using 3,5-dichlorophenol (Hdcp), it was found that one mole of titanium(IV) is extracted together with two moles of acetylacetone (Hacac) and one to three moles of the phenol; one of the extracted species is suggested to be Ti(acac)₂(dcp)₂Hdcp.     

Gold-Catalyzed Cascade Reactions of Alkynes for Construction of Polycyclic Compounds

The development of cascade reactions is an area of considerable interest in modern organic chemistry. Efficient cascade reactions realize the economical synthesis of complex target molecules through multiple bond formations in a single operation. Elementary reactions that form fewer waste products are desirable in terms of atom economy and in order to suppress side product formation in sequential processes. Recent advances in homogeneous gold catalysis have opened up further possibilities for cascade reactions. In this review, recent advances in gold-catalyzed cascade cyclizations of alkynes are summarized. In particular, cascade reactions based on nucleophilic/electrophilic addition, carbene cyclopropanation/insertion, ring expansion, and cycloaddition are highlighted. Notably, many of the cascade reactions shown in this mini-review feature no theoretical waste products.     

Meso-nozzle fabrication for refractory metals using thermal-property mismatch

There are many works focused on making meso-nozzle in metals or polymers for applications like bubble making or spraying. None of them reported successful achievement in fabricating deep holes in metals. A novel method to fabricate a meso-nozzle in metal is proposed in this paper. The method to make a suitable size holes uses refractory metal powders such as Mo and very fine glass fibers of 100 μm in diameter. It utilizes the mismatch in thermal properties between the powder and the fiber. Sintering at a temperature between their melting points causes glass to evaporate leaving a targeted shape of hole and densify the metal powder. Green compacts were prepared at various compressive loads and then subjected to sintering at temperatures below the melting points of the metal powder. The resulted hole exhibited straightness and a circular cross-section along the length. The inspection of the sintered part confirmed that the method is promising to fabricate deep meso-nozzles in metals.     

Interaction between peroxisome proliferator-activated receptor γ and its agonists: docking study of oximes having 5-benzyl-2,4-thiazolidinedione

The molecular modelling of oximes having 5-benzyl-2,4-thiazolidinedione moieties, agonists of the peroxisome proliferator-activated receptor γ (PPARγ), was performed with respect to their structures complexed with the ligand binding domain of PPARγ. For each ligand molecule, the 5-benzyl-2,4-thiazolidinedione head group was used as an anchor and the conformation of the rest of the molecule was searched for the most energetically favorable interaction with the receptor by systematic conformation search and manual modelling. Although both tail-up and tail-down configurations, which have been observed in the crystal structure of eicosapentaenoic acid when complexed with PPARδ, appeared among the lowest energy structures for most of the compounds, potent agonists were found to adopt a configuration similar to that of rosiglitazone when bound to PPARγ, according to the crystal structure. The structure–activity relationships were analyzed based on the receptor–ligand interaction. The alkyl group and the aromatic ring of the tail group of the ligands had hydrophobic interactions with the receptor, and these interactions were found to be essential for the strong activity.     

Energy-efficient ultra-deep desulfurization of kerosene based on selective photooxidation and adsorption

Selective photooxidation and adsorptive desulfurization of kerosene was investigated for fuel cell applications. Photooxidation was conducted using a 5 W low-pressure mercury lamp at 25 °C in the presence of O₂. It was found for the first time that the rates of photooxidation of dominant sulfur compounds remaining in commercial kerosene after hydrogenation were at least 100 times higher than those of benzothiophenes (BTs) and dibenzothiophenes (DBTs), although their molecular forms were not clarified. The photooxidation of these highly reactive sulfur compounds was completed within 30 min and made them removable by adsorbents such as molecular sieves. On the other hand, non-reactive sulfur compounds such as DBTs were removed by adsorbents such as activated carbon. Using this proposed method, which combines selective photooxidation of highly reactive sulfur compounds and adsorptive desulfurization of reactive and non-reactive sulfur compounds, the total sulfur content in kerosene can be efficiently reduced to less than 0.1 μg g⁻¹ (ppm) under mild conditions.     

Damage-free machining of monocrystalline silicon carbide

Cutting tests of monocrystalline SiC, on the surface of which an amorphous layer was preformed by ion implantation, were performed. Ductile-mode machining was observed at a depth of cut smaller than 60 nm. At a depth of cut larger than 60 nm, cracks were observed on the work surface. However, transmission electron micrographs show that crack propagation was obstructed at the interface between the amorphous and crystalline layers even under brittle-mode machining, and no subsurface damage extended into the crystalline layer. The results suggest that the damage-free machining of monocrystalline SiC is possible by surface modification to an amorphous structure.     

Characterization of Solid‐State Reaction of Barium Carbonate and Titanium Dioxide by Spatially Resolved Electron Energy Loss Spectroscopy

A mixture of ultrafine submicrometer‐sized BaCO₃ powder and TiO₂ (rutile) powder was calcined in air at 700°C, 800°C, and 900°C, and then quenched to liquid nitrogen temperature in each case. The cross‐sectional quenched specimens were characterized by spatially resolved electron energy‐loss spectroscopy (SR‐EELS). The energy‐loss near‐edge structures (ELNES) were sequentially extracted at 1.3 to 5.3 nm in width from SR‐EELS image obtained from the rectangularly cut SR‐EELS slit aperture put on the synthesized BaTiO₃ layer and TiO₂ rutile powder. The ELNES of Ti‐L_2,3 edges and Ba‐M_4,5 edges clearly show fine structure changes from the surface of BaTiO₃ layer to the TiO₂ bulk region reflected from crystallinity of synthesized BaTiO₃, lattice distortion of TiO₂ caused by Ba diffusion, and lattice misfit between BaTiO₃ and TiO₂ without formation of Ba₂TiO₄ and other titanate phases.     

Thermal expansion and melting temperature of the half-Heusler compounds: MNiSn (M = Ti,Zr, Hf)

Half-Heusler compounds: MNiSn (M = Ti, Zr, Hf) are considered as a candidate of environmentally friendly and low-cost thermoelectric (TE) materials. Although the thermomechanical properties are quite important when utilizing the half-Heusler compounds in TE devices, such properties have been scarcely reported. In the present study, we tried to collect the data of the thermal expansion coefficient and the melting temperature (T_m) of MNiSn. The thermal expansion coefficient was evaluated by means of two methods: the dilatometer measurement and the high temperature X-ray diffraction analysis. The T_m was evaluated from the differential thermal analysis. The relationship between the thermal expansion coefficient and the T_m of the half-Heusler compounds was studied.     

Organization of gold nanorods on a substrate using a strong magnetic field

The effects of magnetic processing on the organization of gold nanorods (AuNRs)/poly(styrenesulfonate) (PSS) composites using a strong magnetic field were examined by absorption spectra corresponding to surface plasmon on a glass plate and TEM images. The results in the absorption spectra and the TEM images showed that the side-to-side aggregation of AuNRs/PSS composites formed in the presence of a magnetic field directed horizontally to the surface of the sample. In the absence of the magnetic field, side-to-side AuNRs/PSS aggregates were not observed. The effects of magnetic processing are attributed to the induced magnetic dipoles of the AuNRs.