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Abstract Purpose 211At, a promising alpha-particle-emitting radionuclide, can easily volatilize and contaminate the environment. To safely manage this unique alpha-particle-emitting radionuclide, we investigated the permeability of four types of plastic films and two types of rubber gloves against 211At and identified suitable materials that prevent contamination by 211At. Methods Four types of plastic films, polyethylene, polyvinylidene chloride, polyvinyl chloride, and a laminated film, and two types of rubber gloves, latex and nitrile, were examined. Small pieces of filter paper were covered with these materials, and a drop containing 100 kBq of 211At was placed on them. The radioactivity of the pieces of filter paper under the materials was evaluated by measuring counts using a gamma counter and obtaining autoradiograms 3.5 h later. These experiments were also performed using 225Ac, 125I, 111In, 201Tl, and 99mTc. Results 211At solution easily penetrated polyethylene, polyvinyl chloride, and latex rubber. Similar results were obtained for 125I, while other radionuclides did not penetrate films or gloves. These results suggest that halogenic radionuclides under anionic conditions are likely to penetrate plastic films and rubber gloves. Conclusion Our evaluation revealed that, when 211At solution is used, the protection by polyvinylidene chloride, a laminated film, or nitrile rubber would be more effective than that by polyethylene, polyvinyl chloride, or latex rubber.

The synthesis of cyclic thiocarbonates by the cycloaddition of carbon disulfide (CS2) to thiiranes in the presence of silica-immobilized amine catalysts was investigated. The catalytic activities of the silica-immobilized catalysts toward the synthesis of cyclic thiocarbonates were higher than the activities of their homogeneous counterparts. The silica-supported catalysts strongly accelerated the cycloaddition of CS2 to thiiranes, and the pseudo-first-order rate constant of the silica-immobilized catalyst was about 430 times larger than that of the corresponding homogeneous catalyst. The coexistence of the molecular catalyst species and the neighboring surface silanols on the catalyst support was found to be key to the reaction acceleration. In addition to providing improved catalytic activity, the solid-supported catalysts were also shown to be recyclable and reusable for at least five cycles. [ABSTRACT FROM AUTHOR]

The acid−base reaction between lanthanide tris(alkyl) complexes Ln(CH2SiMe3)3(THF)2and 2 equiv of HC5Me4SiMe3in THF or hexane at room temperature resulted in the formation of metallocene complexes [(η5:η1-C5Me4SiMe2CH2)Ln(C5Me4SiMe3)(THF)] (Ln = Y (1a), Nd (1b), Sm (1c), Dy (1d), Lu (1e)), in which the metal center is bonded to one C5Me4SiMe3ligand in a normal η5-form and to the other in a μ-η5:η1-chelate fashion through metalation of a methyl group of the SiMe3substituent. Hydrogenolysis of 1a−ein toluene at room temperature afforded the corresponding metallocene terminal hydride complexes [(C5Me4SiMe3)2LnH(THF)] (Ln = Y (2a), Nd (2b), Sm (2c), Dy (2d), Lu (2e)). Complexes 2a,d,ewere isolated and structurally characterized by X-ray analysis, whereas 2b,c, which possess larger metal ions, existed only in solution in the presence of H2. The reaction of the yttrium hydride complex 2awith 1 equiv of p-methoxyphenylisocyanide yielded the ethylene diamido complex [(C5Me4SiMe3)2YN(Ar)(CH)]2(Ar = C6H4-OMe-p(3)). The reaction of 2a, 2d, and 2ewith a late transition metal hydride complex (C5Me5)IrH4gave the corresponding Ln/Ir heterobimetallic trihydride complexes [(C5Me4SiMe3)2Ln(μ-H)3Ir(C5Me5)] (Ln = Y (4a), Dy (4b), Lu (4c)) with release of H2. [ABSTRACT FROM AUTHOR]

Various substituted nitroaromatics were successfully hydrogenated to the corresponding N-aryl hydroxylamines in excellent yields (up to 99%) using supported platinum catalysts such as Pt/SiO2under a hydrogen atmosphere (1 bar) at room temperature. The key to the fast and highly selective formation of hydroxylamines is the addition of small amounts of amines such as triethylamine and dimethyl sulfoxide; amines promote the conversion of nitroaromatics, while dimethyl sulfoxide inhibits further hydrogenation of hydroxylamines to anilines. The promotive effect depends on which type of amine and primary amine was most effective. The hydrogenation efficiently proceeded in common organic solvents, including isopropanol, diethyl ether, and acetone. This methodology should extend the application range of conventional solid catalysts to fine chemicals synthesis. [ABSTRACT FROM AUTHOR]