Synthesis of 2‐Mercaptobenzaldehyde, 2‐Mercaptocyclohex‐1‐enecarboxaldehydes and 3‐Mercaptoacrylaldehydes

A novel one‐pot approach for the preparation of 2‐mercaptobenzaldehyde, 2‐mercaptocyclohex‐1‐enecarboxaldehydes and 3‐mercaptoacrylaldehydes [(Z)‐3‐mercapto‐2‐methyl‐3‐phenylacrylaldehyde, 3‐mercapto‐3‐(o‐tolyl)acrylaldehyde)] starting from ortho‐bromobenzaldehyde, 2‐chlorocyclohex‐1‐enecarbaldehydes, (Z)‐3‐chloro‐2‐methyl‐3‐phenylacrylaldehyde and 3‐chloro‐3‐(o‐tolyl)acrylaldehyde is reported. The reaction of sulfur with the Grignard reagent of the acetal for the protection of the aldehyde group affords the title compounds through hydrolysis with dilute hydrochloric acid in high yields.     

一个二维Honeycomb-like聚合簇合物 (Et4N)3{[MoS4Cu2(m-CN)]2(m’-CN)}·2MeCN的合成和晶体结构

采用一个预制的簇合物(Et₄N)₂[MoS₄(CuCN)₂]·H₂O(1)和HAc在MeCN中混合反应，生成了一个有趣的二维聚合簇合物(Et₄N)₃{[MoS₄Cu₂(m-CN)]₂(m’-CN)}·2MeCN (2)。通过元素分析，红外光谱及单晶X-射线衍射分析对簇合物2进行了表征。在2的结构中，前驱体1中的MoS₄Cu₂簇核得到了保留，并且此簇核作为三重连接点通过单一氰桥和其他相同的簇核相连，形成一个阴离子型的2D (6,3)（蜂窝状）网络。由预制的簇合物1通过醋酸诱导形成的超分子2表明这种简单的合成方法有可能应用到许多其他相关的体系。     

Homogeneous catalytic fluoroalkylation of thiophenols,phenols and pyrrole by Freons BrCF<Subscript>2</Subscript>CF<Subscript>2</Subscript>Br and CF<Subscript>2</Subscript>ClCFCl<Subscript>2</Subscript>

The use of sulfur dioxide as an electron transfer mediator in the presence of nitrogen bases permits the rather selective fluoroalkylation of thiophenols, phenols, and pyrrole by Freons BrCF₂CF₂Br and CF₂ClCFCl₂ under mild conditions. In the case of thiophenols, the fluoroalkylation occurs to give polyfluoroalkyl aryl sulfides, while phenols and pyrrole are alkylated in the ring. Effects were found for the electronic structure of the substrates and basicity of the medium (pK_α of the pyridines) on the oxidation-reduction properties of the reagents and the efficiency of the reactions studied. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 5, pp. 315–322, September–October, 2007.     

Catalytic Asymmetric [2, 3]－Sigmatropic Rearrangement of Sulfur Ylides Generated from Carbenoids and Allenic 2－Methylphenyl Sulfide

The first investigation on catalytic asymmetric [2,3]-sigmatropic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained.     

Effects of Mo2C loading and H2S concentration on Mo2C/Al2O3 catalyst applied in sulfur‐resistant methanation

Mo₂C/Al₂O₃ catalyst was prepared by the impregnation method with urotropine and ammonium paramolybdate. The catalytic effect of Mo₂C as a typical transition‐metal carbide in sulfur‐resistant methanation was studied. The catalysts prepared were characterized by N₂ adsorption–desorption, X‐ray diffraction, transmission electron microscopy, H₂‐temperature‐programmed reduction, and Raman spectra, with the results confirming the formation of β‐molybdenum carbide on the surface of the catalysts. Studies on catalysts with different loading doses indicate that the optimal loading of Mo₂C/Al₂O₃ is about 15 wt.%, which enables CO conversion rate of up to 47%, with methane selectivity of up to 53%. This work further explored the effect of different concentrations of H₂S in the raw gas on the performance of the catalyst, with the results showing that high concentration of H₂S (>1500 ppm) can lead to sulfuration of active species on the catalyst, while resulting in a decrease in the catalytic activity.     

Studies on the metabolism and detectability of the emerging drug of abuse diphenyl‐2‐pyrrolidinemethanol (D2PM) in rat urine using GC‐MS and LC‐HR‐MS/MS

In the last years, the number of new psychoactive substances, so‐called ‘legal highs’, has enormously increased. They are sold via online shops often with inaccurate and false information about the content. The aim of this work was to study the metabolism and the detectability of the drug of abuse diphenyl‐2‐pyrrolidinemethanol (D2PM) in rat urine using gas chromatography‐mass spectrometry and liquid chromatography‐high resolution‐tandem mass spectrometry. Five phase I and two phase II metabolites were identified suggesting hydroxylation at the pyrrolidine and diphenyl part as the main metabolic steps. Assuming similar kinetics, an intake of D2PM should be detectable in human urine mainly via its metabolites. Copyright © 2013 John Wiley & Sons, Ltd.     

Interaction of Cl<Subscript>2</Subscript> and SO<Subscript>2</Subscript> with Finely Divided In<Subscript>2</Subscript>O<Subscript>3</Subscript>

The effect of O₂, Cl₂, and SO₂ on electrophysical and sorption properties of powdered In₂O₃ with a large specific area is studied at 23–200°C. The specimen is most sensitive to Cl₂ and SO₂ at near-room temperatures.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 529–536.Original Russian Text Copyright © 2005 by Vinokurova, Derlyukova.     

Two Keggin Templated Supramolecular Compounds by Exerting the Chelate and Linking Dual Roles of the Ligand 2, 2′‐Biimidazole

Two new Keggin templated supramolecular compounds, [Zn₂(H₂biim)₅(SiM₁₂O₄₀)] · 4H₂O [M = W ( 1 ), Mo ( 2 )] (H₂biim = 2, 2′‐biimidazole), were synthesized under hydrothermal conditions by using the ligand 2, 2′‐biimidazole. They were characterized by single‐crystal X‐ray diffraction, elemental analyses, IR and photoluminescence spectroscopy as well as cyclic voltammetry. The two isostructural compounds are constructed by two discrete supramolecular moieties: the inorganic chains consist of Keggin anions and metal‐organic chains constructed by [Zn₂(H₂biim)₅]⁴⁺ subunits. In the dinuclear [Zn₂(H₂biim)₅]⁴⁺ subunit, the H₂biim ligands exhibit a dual role, chelating and linking. The metal‐organic chains further construct a 3D supramolecular framework with channels, in which the Keggin‐based inorganic chains are accommodated. The electrochemical behaviors of compounds 1 and 2 bulk‐modified carbon paste electrodes ( 1 ‐CPE, 2 ‐CPE) were studied.     

Transformation between α‐helix and β‐sheet structures of one and two polyglutamine peptides in explicit water molecules by replica‐exchange molecular dynamics simulations

Aggregation of polyglutamine peptides with β‐sheet structures is related to some important neurodegenerative diseases such as Huntington's disease. However, it is not clear how polyglutamine peptides form the β‐sheets and aggregate. To understand this problem, we performed all‐atom replica‐exchange molecular dynamics simulations of one and two polyglutamine peptides with 10 glutamine residues in explicit water molecules. Our results show that two polyglutamine peptides mainly formed helix or coil structures when they are separated, as in the system with one‐polyglutamine peptide. As the interpeptide distance decreases, the intrapeptide β‐sheet structure sometimes appear as an intermediate state, and finally the interpeptide β‐sheets are formed. We also find that the polyglutamine dimer tends to form the antiparallel β‐sheet conformations rather than the parallel β‐sheet, which is consistent with previous experiments and a coarse‐grained molecular dynamics simulation. © 2014 Wiley Periodicals, Inc.     

Syntheses of 2‐Keto‐3‐deoxy‐D‐xylonate and 2‐Keto‐3‐deoxy‐L‐arabinonate as Stereochemical Probes for Demonstrating the Metabolic Promiscuity of Sulfolobus solfataricus Towards D‐Xylose and L‐Arabinose

Practical syntheses of 2‐keto‐3‐deoxy‐D ‐xylonate (D ‐KDX) and 2‐keto‐3‐deoxy‐L ‐arabinonate (L ‐KDA) that rely on reaction of the anion of ethyl 2‐[(tert‐butyldimethylsilyl)oxy]‐2‐(dimethoxy phosphoryl) acetate with enantiopure glyceraldehyde acetonide, followed by global deprotection of the resultant O‐silyl‐enol esters, have been developed. This has enabled us to confirm that a 2‐keto‐3‐deoxy‐D ‐gluconate aldolase from the archaeon Sulfolobus solfataricus demonstrates good activity for catalysis of the retro‐aldol cleavage of both these enantiomers to afford pyruvate and glycolaldehyde. The stereochemical promiscuity of this aldolase towards these enantiomeric aldol substrates confirms that this organism employs a metabolically promiscuous pathway to catabolise the C5‐sugars D ‐xylose and L ‐arabinose.     

Theoretical study of the gas‐phase ion pairs SN2 reactions of LiX with CH3SY (X,Y = F,Cl, Br,I)

The gas‐phase ion pair S_N2 reactions at saturated sulfur LiX + CH₃SY → CH₃SX + LiY (X, Y = F, Cl, Br, I) are investigated using the CCSD(T) calculations. The calculated results show that the reactions LiX + CH₃SY are exothermic only when the nucleophile is a heavier lithium halide. Central barrier heights are found to depend primarily on the identity of nucleophile LiX, decreasing in the order LiF > LiCl > LiBr > LiI. Another interesting feature of the ion pair reactions at sulfur is the good correlation between the reaction barriers with geometrical looseness of Li? X and S? Y bonds in the transition state structures. The data for the reaction barriers show good agreement with the prediction of the Marcus equation and its modification. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Biological Effects of β-Glucans on Osteoclastogenesis

Although the anti-tumor and anti-infective properties of β-glucans have been well-discussed, their role in bone metabolism has not been reviewed so far. This review discusses the biological effects of β-glucans on bone metabolisms, especially on bone-resorbing osteoclasts, which are differentiated from hematopoietic precursors. Multiple immunoreceptors that can recognize β-glucans were reported to be expressed in osteoclast precursors. Coordinated co-stimulatory signals mediated by these immunoreceptors are important for the regulation of osteoclastogenesis and bone remodeling. Curdlan from the bacterium Alcaligenes faecalis negatively regulates osteoclast differentiation in vitro by affecting both the osteoclast precursors and osteoclast-supporting cells. We also showed that laminarin, lichenan, and glucan from baker’s yeast, as well as β-1,3-glucan from Euglema gracilisas, inhibit the osteoclast formation in bone marrow cells. Consistent with these findings, systemic and local administration of β-glucan derived from Aureobasidium pullulans and Saccharomyces cerevisiae suppressed bone resorption in vivo. However, zymosan derived from S. cerevisiae stimulated the bone resorption activity and is widely used to induce arthritis in animal models. Additional research concerning the relationship between the molecular structure of β-glucan and its effect on osteoclastic bone resorption will be beneficial for the development of novel treatment strategies for bone-related diseases.     

Synthesis and Electrochemical Performance of Graphene‐like WS2

Graphene‐like and platelike WS₂ were obtained by solid‐state reactions. High‐resolution (HR) TEM, BET, and Raman scattering studies show that the graphene‐like WS₂ is a few‐layer‐structured material. It exhibits better electrochemical performances than the platelike WS₂. Structural characterization indicates that metallic W and Li₂S are the end products of discharge (0.01 V versus Li⁺/Li), whereas metallic W and S are the recharge (3.00 V) products. In addition, X‐ray absorption near‐edge structure (XANES) characterization shows that the d electrons of W deviate towards the Li (or S) atom during the discharge/charge process, thus forming a weak bond between W and Li₂S (or S).     

Activation of SO2 and CO2 by Trivalent Uranium Leading to Sulfite/Dithionite and Carbonate/Oxalate Complexes

The first sulfite [{((^nP,MeArO)₃tacn)U^IV}₂(μ‐κ¹:κ²‐SO₃)] (tacn=triazacyclononane) and dithionite [{((^nP,MeArO)₃tacn)U^IV}₂(μ‐κ²:κ²‐S₂O₄)] complexes of uranium from reaction with gaseous SO₂ have been prepared. Additionally, the reductive activation of CO₂ was investigated with respect to the rare oxalate [{((^nP,MeArO)₃tacn)U^IV}₂(μ‐κ²:κ²‐C₂O₄)] formation. This ultimately provides the unique S₂O₄^2?/C₂O₄^2? and SO₃^2?/CO₃^2? complex pairs. All new complexes were characterized by a combination of single‐crystal X‐ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and ¹H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO₂ and CO₂ show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes.     

Transition Metal‐Catalysed Direct C−H Bond Functionalizations of 2‐Pyridone Beyond C3‐Selectivity

2‐Pyridone is a ubiquitous motif in natural products, drug molecules, ligands in catalysis and organic materials. There is a necessity of direct step‐economic methods for the construction of 2‐pyridone based molecules. Strategically, the primary developments have led to the C3‐functionalizations due to the inherent reactivity of this center. Despite this, many elegant transition metal‐catalysed methods have been established to introduce versatile functional groups at the C4, C5 and C6‐position via direct C?H bond functionalizations. This minireview focuses on the categorized introduction of different functional groups at the 2‐pyridone scaffolds beyond C3‐selectivity and discusses substrate scope, limitations and plausible mechanistic details.     

S‐((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon‐Selective Electrophilic Difluoromethylation of β‐Ketoesters, β‐Diketones,and Dicyanoalkylidenes

S‐((Phenylsulfonyl)difluoromethyl)thiophenium salts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiophenium salts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF₂H group to sp³‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (phenylsulfonyl)difluoromethyl group can be readily transformed into CF₂H under mild reaction conditions. Enantioselective electrophilic difluoromethylation was also achieved in the presence of bis(cinchona) alkaloids.     

色谱保留值法测定碘和硫在超临界流体CO2中的溶解度

用色谱保留值法测定了单质碘和单斜硫在不同温度及压力下在超临界二氧化碳中的溶解度，并用超临界平衡饱和萃取法验证了测定值，结果满意。     

Properties of alkylbenzimidazoles for CO2 and SO2 capture and comparisons to ionic liquids

To date, few reports have been concerned with the physical properties of the liquid phases of imidazoles and benzimidazoles-potential starting materials for a great number of ionic liquids. Prior research has indicated that alkylimidazole solvents exhibit different, and potentially advantageous physical properties, when compared to corresponding imidazolium-based ionic liquids. Given that even the most fundamental physical properties of alkylimidazole solvents have only recently been reported, there is still a lack of data for other relevant imidazole derivatives, including benzimidazoles. In this work, we have synthesized a series of eight 1-n-alkylbenzimidazoles, with chain lengths ranging from ethyl to dodecyl, all of which exist as neat liquids at ambient temperature. Their densities and viscosities have been determined as functions of both temperature and molecular weight. Alkylbenzimidazoles have been found to exhibit viscosities that are more similar to imidazolium-based ILs than alkylimidazoles, owed to a large contribution to viscosity from the presence of a fused ring system. Solubilities of CO2 and SO2, two species of concern in the emission of coal-fired power generation, were determined for selected alkylbenzimidazoles to understand what effects a fused ring system might have on gas solubility. For both gases, alkylbenzimidazoles were determined to experience physical, non-chemically reactive, interactions. The solubility of CO2 in alkylbenzimidazoles is 10%-30% less than observed for corresponding ILs and alkylimidazoles. 1-butylbenzimidazole was found to readily absorb at least 0.333 gram SO2 per gram at low pressure and ambient temperature, which could be readily desorbed under an N2 flush, a behavior more similar to imidazolium-based ILs than alkylimidazoles. Thus, we find that as solvents for gas separations, benzimidazoles share characteristics with both ILs and alkylimidazoles.     

The effect of citric acid on the catalytic activity of nano‐sized MoS2 toward sulfur‐resistant CO methanation

In this work, a facile hydrothermal route was used to prepare nano‐sized MoS₂ catalyst. The effect of citric acid during the MoS₂ preparation process on the catalytic activity of sulfur‐resistant CO methanation was investigated. It was found that citric acid played an adverse role on the catalytic activity of MoS₂ toward sulfur‐resistant CO methanation. However, CO methanation performance turned out to be better when NH₂OH?HCl as a reductant was removed during the catalyst preparation process. The X‐ray diffraction (XRD) and infrared spectroscopy (IR) were performed to discuss the possible mechanism for the effect of citric acid towards CO methanation performance.