Novel approach for electrochemical preparation of sulfur nanoparticles

An electrochemical method is presented for the preparation of sulfur nanoparticles (S-NPs) from thiosulfate ion. The particle size of the S-NPs can be adjusted between 35 and 65 nm by varying parameters such as the initial concentration of thiosulfate. The solvent/non-solvent precipitation method was also applied to the preparation of S-NPs for comparison. In this case, the use of hot alcohol and cold water as solvent/non-solvent system along with 100 ml·min^?1 flow rate for co-mixing of non-solvent resulted in the formation of S-NPs in a typical size of 250 nm that are fairly homogeneous in shape and have a narrow particle size distribution. The results revealed that, in comparison to the precipitation process, the electro-synthetic method offers simplicity, higher efficiency, improved size control, and less environmental contamination.

Selective Oxidation of Sulfides to Sulfoxides and Sulfones Using n -Butyltriphenylphosphonium Dichromate (Bu n PPh3)2Cr2O7 in the Presence of Aluminium Chloride in Solution and Under Microwave Irradiation

A wide variety of sulfides are efficiently oxidized to their corresponding sulfoxides and sulfones in excellent yields using n-butyltriphenylphosphonium dichromate (BTPPDC) in the presence of aluminium chloride in acetonitrile solution and under microwave irradiation. In addition, selective oxidation of sulfides in the presence of functional groups such as a carbon–carbon double bond, ketone, oxime, aldehyde, ether, and acetal can be considered as a noteworthy advantage of this method.     

Bis[N‐(4‐nitrophenyl)thiobenzamidato]mercury(II)

The molecule of the title compound, [Hg(C₁₃H₉N₂O₂S)₂], has approximate twofold rotation symmetry, with the Hg atom in an essentially linear two‐coordinate HgS₂ environment supported by secondary π interactions with the nitrophenyl rings of both ligands. The ligands are in the imine–thiolate rather than the amine–thione tautomeric form.     

A domino approach for the synthesis of naphtho[2,1-b]furan-2(1H)-ones from azlactones

A domino approach to naphtho[2,1-b]furan-2(1H)-one derivatives from (Z)-4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) and 2-naphthols catalyzed by p-TSA with reasonably moderate to high yields, has been developed. This protocol illustrates attractive features including a unique and convenient process.     

RuIII(OTf)SalophenCH2–NHSiO2–Fe: an efficient and magnetically recoverable catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane

Efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by ruthenium(III) complex of chloromethylated Salophen supported on nanomagnetic materials is reported. First, the iron nanomagnets were silica coated, functionalized with amine and then ruthenium CM‐Salophen was successfully bonded to their surface. The catalyst, Ru^III(OTf)SalophenCH₂–NHSiO₂–Fe, was characterized by elemental analysis, FT‐IR and UV–visible spectroscopic techniques, transmission electron microscopy and inductively coupled plasma (ICP). The Ru^III(OTf)SalophenCH₂–NHSiO₂–Fe catalyzed trimethylsilylation of primary and secondary alcohols as well as phenols, and the corresponding TMS ethers were obtained in high yields and short reaction times at room temperature. This new heterogenized trimethylsilylation catalyst is easily recovered with a magnet and showed no appreciable loss of activity even after five consecutive runs. Copyright © 2014 John Wiley & Sons, Ltd.     

Manganese(III) porphyrin supported on multi-wall carbon nanotubes: A highly efficient and reusable biomimetic catalyst for epoxidation of alkenes with sodium periodate

In this paper, the biomimetic epoxidation of alkenes catalyzed by tetrakis(p-aminophenyl)porphyrinatomanganese(III) chloride, [Mn(TNH₂PP)Cl], supported on functionalized multi-wall carbon nanotubes, MWCNT, is reported. The catalyst, [Mn(TNH₂PP)Cl-MWCNT], was used as an efficient and heterogeneous catalyst for epoxidation of alkenes with NaIO₄ at room temperature, in the presence of imidazole as an axial ligand. This new heterogenized catalyst was characterized by elemental analysis, FT IR spectroscopy, diffuse reflectance UV–Vis spectrophotometry, scanning electron microscopy and transmission electron microscopy. The biggest advantage of Mn(TNH₂PP)Cl-MWCNT is its high reusability in the oxidation reactions, in which the catalyst was reused several times without significant loss of its catalytic activity.     

Effective topological spaces II: A hierarchy

This paper (which is the continuation of the preceding paper [7]) is an investigation of definability hierarchies on effective topological spaces. An open subset $\text{U}$ of an effective space X is definable iff there is a parameter free definition φ of $\text{U}$ so that the atomic predicate symbols of φ are recursively open relations on X. The complexity of a definable open set may be identified with the quantifier complexity of its definition. For example, a set $\text{U}$ is an ????-set if it has an ???? parameter free definition using only recursively open predicate symbols. Since X is not equipped with a natural pairing apparatus such a $\text{U}$ need not be an ???-set.Let Σ denote the class of all ?-sets, ??-sets, ???-sets etc. We show that an open set is in Σ iff it is equivalent modulo a nowhere dense set to a recursively enumerable open set (such sets are said to be essentially recursively enumerable or e.r.e.). Thus Σ = e.r.e. Indeed we show the existence of a universal Σ-set as well as the existence of universal sets for higher levels of the definability hierarchy.