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A sulfur-involved ligation for thioamide quasi-peptides was developed via amino acids and amino aldehydes coupling. The key to the transformation was the chelation of copper with imines for chiral activation and fixation. In this environment, linear polysulfur decreased the alkalinity of single sulfur anions to prevent racemization caused by the interaction between sulfur and sodium sulfide. Dipeptides, tripeptides, tetrapeptides, and the linkage between the drug and amino acids were successfully obtained.

Sodium-conducting sulfide glasses are promising materials for the next generation of solid-state batteries. Deep insight into the glass structure is required to ensure a functional design and tailoring of vitreous alloys for energy applications. Using pulsed neutron diffraction supported by first-principles molecular dynamics, we show a structural diversity of Na2S-As2S3 sodium thioarsenate glasses, consisting of long corner-sharing (CS) pyramidal chains CS-(AsSS2/2)k, small AspSq rings (p + q ≤ 11), mixed corner- and edge-sharing oligomers, edge-sharing (ES) dimers ES-As2S4, and isolated (ISO) pyramids ISO-AsS3, entirely or partially connected by sodium species. Polysulfide S-S bridges and structural units with homopolar As-As bonds complete the glass structure, which is basically different from structural motifs predicted by the equilibrium phase diagram. In contrast to superionic silver and sodium sulfide glasses, characterized by a significant population of isolated sulfur species Siso (0.20 < Siso/Stot < 0.28), that is, sulfur connected to only mobile cations M+ with a usual M/Siso stoichiometry of 2, poorly conducting Na2S-As2S3 alloys exhibit a modest Siso fraction of 6.2%.

Corrosion by sulfur compounds is a long-standing challenge in many engineering applications. Specifically, designing a coating that protects metals from both abiotic and biotic forms of sulfur corrosion remains an elusive goal. Here we report that atomically thin layers (∼4) of hexagonal boron nitride (hBN) act as a protective coating to inhibit corrosion of the underlying copper (Cu) surfaces (∼6-7-fold lower corrosion than bare Cu) in abiotic (sulfuric acid and sodium sulfide) and biotic (sulfate-reducing bacteria medium) environments. The corrosion resistance of hBN is attributed to its outstanding barrier properties to the corrosive species in diverse environments of sulfur compounds. Increasing the number of atomic layers did not necessarily improve the corrosion protection mechanisms. Instead, multilayers of hBN were found to upregulate the adhesion genes in Desulfovibrio alaskensis G20 cells, promote cell adhesion and biofilm growth, and lower the protection against biogenic sulfide attack when compared to the few layers of hBN. Our findings confirm hBN as the thinnest coating to resist diverse forms of sulfur corrosion.

A novel domino reaction from benzaldehydes and 2-acetylfuran/2-acetylthiophene with sodium sulfide was developed to synthesize a series of tetrahydrothiopyran (THTP) derivatives. The reaction proceeded well to construct a tetrahydrothiopyran ring and five new bonds in one step. A mechanism is proposed, involving a stepwise Aldol/double Michael addition/Aldol (AMMA) reaction cascade. In this transformation, sodium sulfide acts as a nucleophile and base. This method is characterized by transition-metal-free, commercially available starting materials and mild reaction conditions.

Development of a simple and efficient strategy for improving the catalytic activity of cobalt-based catalysts toward hydrogen evolution from sodium borohydride (NaBH4) is paramount but remains challenging. Here, we reported a facile and efficient approach to tune the catalytic performance for NaBH4 hydrolysis with Co-based catalysts prepared by using cobalt sulfate as a precursor or a mixture of sulfur-containing sodium salts/cobalt salts as a raw material. With the use of cobalt sulfate as the precursor, the CoSO4-doped Co3O4 sample was formed and it exhibited excellent activity with the generation of ∼500 mL of hydrogen gas from NaBH4 hydrolysis under mild conditions. In terms of sulfur-free cobalt salts (e.g., cobalt chloride, cobalt nitrate, and cobalt acetate) as precursors, the obtained Co-based samples were found to be entirely ineffective for hydrogen production. Interestingly, during the cobalt-based catalyst preparation, the introduction of sodium sulfate or sodium sulfide can considerably accelerate hydrogen production. On the contrary, adding sulfur-bearing salts did not inspire any activity improvement only during the hydrogen generation reaction. Control experiments indicate that during catalyst preparation, the presence of Na2SO4 and Na2S is beneficial for the in situ transformation of Co3O4 into catalytically active Co-B alloys, accompanying a positive change in surface morphology during the NaBH4 hydrolysis, thereby inducing an excellent hydrogen generation rate of up to 4425 mL·min-1·gcat-1.

Eight new sulfur-bridged pyranonaphthoquinone (PNQ) dimers, naquihexcins C-J (1-8), a new PNQ monomer, naquihexcin K (10), and three known analogues (9, 11, and 12) were isolated from Streptomyces sp. KIB3133. The new structures were elucidated by interpretation of spectroscopic data. Dimer 4 was synthesized via a cascade SN2 reactions between two monomers and sodium sulfide, an approach motivated by the proposed biosynthetic pathway of dimeric pyranonaphthoquinones. Naquihexcin E (3) exhibited moderate HIV-1 inhibitory activity. Naquihexcins C (1), E (3), and I (7) showed inhibitory effects against two tumor cell lines (HL-60 and MCF-7) with IC50 values ranging from 1.4 to 16.1 μM.

Photocatalytic hydrogen generation over semiconductor photocatalysts has attracted considerable attention over the past few decades. This experiment is designed for sophomore- and higher-level undergraduates who are in the majors of materials chemistry, analytical chemistry, catalysis, or chemical engineering. In this experiment, CdS nanoparticles and nanosheets were first fabricated with a one-step direct-precipitation reaction and a two-step precipitation–ion-exchange reaction, respectively, and then used as photocatalysts for visible-light hydrogen evolution from water, in the presence of noble-metal Pt nanoparticles as in situ cocatalysts and sodium sulfide and sulfite (Na2S/Na2SO3) as sacrificial reagents. A gas chromatograph with a thermal-conductivity detector (GC-TCD) was used to quantitatively monitor the produced hydrogen gas. This interdisciplinary experiment is expected to give students an introduction to nanomaterial synthesis, the general process of photocatalytic hydrogen generation, and the principles and use of instruments. Upon the completion of the experiment, students understand how chemistry can be utilized for renewable-energy applications.

Spent Li-ion batteries (LIBs) are highly rich in cobalt and lithium that need to be recovered to reduce shortages of these valuable metals and decrease their potential environmental risks. This study applied bioleaching using Aspergillus niger strains MM1 and SG1 and Acidithiobacillus thiooxidans 80191 for removal of Co and Li from spent LIB under type 1 and type 2 conditions. Moreover, metal recovery was attempted from the fungal leaching solution by sodium sulfide, sodium hydroxide, and sodium oxalate for Co and then for Li using sodium carbonate. The findings of this work show that metal removal in fungal bioleaching under type 2 system was highly comparable or even better than bacterial or acid leaching. A significant quantity of Co (82%) and Li (100%) dissolution was observed in strain MM1; however, metal solubilization was poor in strain 80191 because only 22% Co and 66% Li solubilized. A high amount of Co precipitated potentially as cobalt sulfide (100%), cobalt hydroxide (100%), or cobalt oxalate ...

Solid-state sodium batteries, a relatively safe and potentially cost-effective energy-storage technology, have attracted increasing scientific attention recently for application in stationary grid-scale energy storage. Identifying solid electrolytes with high electrochemical stability and high Na+-ion conductivity at room temperature is critically important to enable high energy densities with enhanced rate capabilities. We evaluated sodium sulfide-silicon sulfide, xNa2S + (1- x)SiS2, glasses as potential glassy solid electrolytes (GSEs) using molecular dynamics (MD) simulations. We employed ab initio MD to determine ion conduction mechanisms, to calculate energy barriers for ion hops, and to correlate these to the local short-range structure of 0.50Na2S + 0.50SiS2 glass. To simulate much larger systems for accurately calculating the ionic conductivity, we parameterized empirical Buckingham-type potential and performed classical MD simulations. After validating these calculations by comparing the structure obtained from MD to that from X-ray scattering data, we calculated the ionic conductivity of these glasses for the range of 0.33 ≤ x ≤ 0.67 compositions. The calculated ionic conductivities at room temperature were in the range of ∼10-5 S/cm for the x = 0.50 composition and increased significantly with sodium sulfide ( x) content. These calculations provide theoretical insights into the role of Na2S content on the ionic conductivity of GSEs aiding in the selection of specific compositions to enhance the ionic conductivity.

To find some new desulfurizers for the smelter off-gas containing high levels of SO2, both the sulfur recovery performance and the regeneration performance of the sulfides of alkali metals and alkaline-earth metals were compared in both simulation and experiment. Although sodium sulfide(Na2S) showed a good sulfur recovery performance, its regeneration performance was poor due to the production of polysulfides. Calcium sulfide(CaS) was a feasible option of the desulfurizer because both its sulfur recovery performance and regeneration performance were satisfactory. CaS was prepared after the reduction of the commercial CaSO4(Red-Ca), the flue gas desulphurization gypsum(Red-FGD), the phosphogypsum(Red-P) and the titanogypsum(Red-Ti), respectively. The results showed that the performances of Red-Ca and Red-FGD were quite similar and both of them were distinctly better than Red-P and Red-Ti. According to XRF analysis and XRD patterns, the impurities in Red-P and Red-Ti reduced the activity of CaS. Both the su...

Pollution from the leather industry is of great concern for tanners worldwide. The unhairing and fiber-opening processes, which contribute the majority of the pollution through the use of sodium sulfide and calcium hydroxide, were replaced in this study by processes using an enzyme and the imidiazolium-based ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate. In addition, the deliming process, which is typically applied after liming operations, was completely avoided, eliminating the use of ammonium salts, which leads to other environmental concerns. The extent of fiber opening of the matrix was analyzed by estimating the proteoglycan content and performing histological studies. The physical strength properties of the IL-treated leathers were found to be comparable to standard norms. This study thus demonstrates that ILs can be successfully employed for unhairing, where they can enhance the activity of unhairing enzymes, as well as for the fiber-opening process of leather making.

This work reports a new type of near-infrared (NIR) laser-inducible antimicrobial composite paper based on copper sulfide nanoparticles (CuS NPs). For the first time, a smart and green method to prepare CuS NPs was developed by taking advantage of the copper–amine complex as the copper source and sodium sulfide as the sulfur source at room temperature, in which a biopolymer xylan was used as the growth template and stabilizing agent. The obtained xylan/CuS NPs composites (CuS@Xylan NPs) were spherical and stable with an average diameter of ∼10 nm. CuS@Xylan NPs were subsequently allowed to penetrate into cellulose nanofiber (CNF) networks to prepare the composite paper. This CuS@Xylan NPs/CNF composite paper showed strong NIR laser-inducible antimicrobial effect on Escherichia coli, Bacillus subtilis, Stapylococcus aureus, and Aspergillus niger. In addition, the tensile strength, tear strength, and burst strength of the composite paper were improved likely due to the strong hydrogen bonding between xylan ...

Zero-valent iron nanoparticles (nZVI) synthesized in the presence of reduced sulfur compounds have been shown to degrade trichloroethene (TCE) at significantly higher rates. However, the applicability of sulfidation as a general means to enhance nZVI reactivity under different particle preparation conditions and the underlying cause for this enhancement effect are not well understood. In this study, the effects of sulfidation reagent, time point of sulfidation, and sulfur loading on the resultant particles were assessed through TCE degradation experiments. Up to 60-fold increase in TCE reaction rates was observed upon sulfidation treatment, with products being fully dechlorinated hydrocarbons. While the reactivity of these sulfur-treated nZVI (S-nZVI) was relatively unaffected by the sulfidation reagent (viz., sodium sulfide, dithionite, or thiosulfate) or the sequence of sulfidation relative to iron reduction, TCE reaction rates were found to depend strongly on sulfur to iron ratio. At a low sulfur loading, TCE degradation was accelerated with increasing sulfur dose. The rate constant reached a limiting value, however, as the sulfur to iron mole ratio was greater than 0.025. Different from previous propositions that iron sulfidation leads to more efficient TCE or tetrachloroethene (PCE) degradation by enabling depassivation of iron surface, affording catalytic pathways, or facilitating electron transfer, we show that the role of sulfur in nZVI lies essentially in its ability to poison hydrogen recombination, which drives surface reactions to favor reduction by atomic hydrogen. This implies that the reactivity of S-nZVI is contaminant-specific and is selective against the background reaction of water reduction. As the effect of sulfur manifests through surface processes, sulfidation represents a broadly applicable surface modification approach to modulate or increase the reactivity of nZVI for treating TCE and other related contaminants.

We describe herein facile thiophene annulation reactions promoted by sodium sulfide hydrate (Na2S·9H2O) for the synthesis of acene(di)thiophenes that can be further utilized as organic semiconductors or building blocks for the elaboration of semiconducting oligomers and polymers. Sodium sulfide hydrate is an efficient source of sulfur for both the aromatic nucleophilic substitution (SNAr) reaction and the nucleophilic hydrogen substitution (SNH) reaction to give a range of electron-donating acene(di)thiophenes and an electron-deficient naphtho[2,3-b:6,7-b′]dithiophene diimide (NDTI), respectively. We also describe organic semiconducting materials on the basis of these acene(di)thiophenes and their use in organic devices, such as organic field-effect transistors and organic photovoltaics, and demonstrate that synthetic evolution is one of the keys to promoting the field of organic semiconducting materials.

An engineered strain of Stenotrophomonas maltophilia (SMCD1) is capable of the direct extracellular biomineralization of CdS quantum dot nanocrystals from buffered aqueous solution of cadmium acetate and l-cysteine without the addition of a chemically reactive precursor. Nanocrystal synthesis is strongly influenced by both the l-cysteine/cadmium acetate ratio and pH of the solution. The observed trends are consistent with l-cysteine acting as both a sulfur source and nanocrystal capping agent. Enzymatic turnover of l-cysteine by a putative cystathionine γ-lyase forms reactive sulfur in solution, removing the requirement for addition of reactive sodium sulfide typical of most other biomineralization approaches. The utility of the biomineralized quantum dots is demonstrated by phase transfer from the aqueous to the organic phase and subsequent incorporation into a quantum dot sensitized solar cell and chemical growth of a ZnS shell onto the biomineralized CdS core.

Operation of sodium–sulfur batteries at room temperature has been proposed and studied for about a decade, but polysulfide-shuttle through the traditional battery separator and low-utilization of the sulfur cathode commonly have been the major challenges. Also, because of the highly active nature of the sodium metal, the conventional room temperature sodium–sulfur (RT Na–S) battery concept with the sodium–metal anode and elemental sulfur cathode imposes serious safety concerns. To overcome the above difficulties, we present here a RT Na–S system with an advanced membrane-electrode-assembly (MEA) comprising a carbon-coated, presodiated Nafion membrane (Na-Nafion) and a sodium sulfide (Na2S) cathode. The Na-Nafion membrane provides a facile Na+-ion conductive path and serves as a cation-selective shield to prevent the migration of the polysulfides to the anode. The carbon coating on the Na-Nafion plays an upper-current-collector role and thereby improves the electrochemical utilization of the active Na2S. E...

Using colloidal CdSe nanowire (NW) field-effect transistors (FETs), we demonstrated the dependence of carrier transport on surface stoichiometry by chemically manipulating the atomic composition of the NW surface. A mild, room-temperature, wet-chemical process was devised to introduce cadmium, selenium, or sulfur adatoms at the surface of the NWs in completed devices. Changes in surface composition were tested for by energy dispersive spectroscopy and inductively coupled plasma-atomic emission spectroscopy and through the use of the vibrational reporter thiocyanate. We found that treatment with cadmium acetate enhances electron currents, while treatment with sodium selenide or sodium sulfide suppressed them. The efficacy of doping CdSe NWs through subsequent thermal diffusion of indium was highly dependent on the surface composition. While selenium-enriched CdSe NW FETs were characterized by little to no electron currents, when combined with indium, they yielded semimetallic devices. Sulfur-enriched, indium-doped devices also displayed dramatically enhanced electron currents, but to a lesser extent than selenium and formed FETs with desirable ION/IOFF10(6). The atomic specificity of the electronic behavior with different surface chalcogens suggested indium was bound to chalcogens at the NW surface, indicating commonalities with and implications for indium-containing CdSe nanocrystal films. Low temperature measurements of indium-doped CdSe NW FETs showed no evidence of impurity scattering, further supporting the existence of an indium-chalcogen interaction at the surface rather than in the core of the NW.

Cadmium sulfide/magnetite/polymer multifunctional hybrid nanoparticles are prepared by crystallizing CdS in a controlled manner on the surface of phosphonate-functionalized polystyrene particles with a magnetic core. The supporting polymer magnetoresponsive nanoparticles are produced by a modified miniemulsion polymerization process: a first miniemulsion containing the core monomer (styrene) and a phosphonate-functionalized surface-active monomer is mixed with a second miniemulsion containing magnetite nanoparticles capped with oleic acid and the same surface-active monomer. The chalcogenide formation occurs in situ at the surface of the polymer particles by adding a precipitating agent (sodium sulfide) at a controlled rate. The phosphonate groups on the surface of the polymer particles have the ability to bind the cadmium ions and act as nucleating centers from which the controlled crystallization of CdS takes place. The resulting hybrid particles show a “raspberry-like” structure, with CdS nanocrystals ...

A SnS2/graphene (SnS2/G) hybrid was synthesized by a facile one-step solvothermal route using graphite oxide, sodium sulfide, and SnCl4·5H2O as the starting materials. The formation of SnS2 and the reduction of graphite oxide occur simultaneously. Ultrathin SnS2 nanoplates with a lateral size of 5-10 nm are anchored on graphene nanosheets with a preferential (001) orientation, forming a unique plate-on-sheet structure. The electrochemical tests showed that the nanohybrid exhibits a remarkably enhanced cycling stability and rate capability compared with bare SnS2. The excellent electrochemical properties of SnS2/G could be ascribed to the in situ introduced graphene matrix which offers two-dimensional conductive networks, disperses and immobilizes SnS2 nanoplates, buffers the volume changes during cycling, and directs the growth of SnS2 nanoplates with a favorable orientation.

Process Research and Development activities leading to a new and efficient route to bendamustine hydrochloride, 1, the active ingredient in Treanda, a treatment for blood cancers, are disclosed. Two key features of this new process include a one-pot hydrogenation/dehydration sequence to construct the benzimidazole moiety and a novel reductive alkylation using chloroacetic acid and borane to install the bischloroethyl side chain. The number of synthetic steps has been significantly reduced to five from the eight in the current commercial process. The overall yield has been improved from 12% to 45%. Additionally, this new route eliminates chloroform, ethylene oxide, and sodium sulfide. Scale-up of the new route has been successfully demonstrated to prepare kilogram quantities of bendamustine hydrochloride.

The aqueous extraction of hemicelluloses has gained increasing interest with new emerging applications for hemicelluloses in the modern forest-based biorefinery concept. The extraction kinetics play a key role in their industrial utilization. The traditional kinetic studies and models for the selective dissolution of softwoods, however, always incorporate high concentrations of sodium hydroxide and sodium sulfide relevant to pulping, and the kinetics in pure water is left outside the scope of these investigations. Aqueous extraction of hemicelluloses from spruce sapwood was investigated with a new cascade reactor setup, which was developed for intensified investigation of solid−liquid dissolution kinetics. The experiments were performed at 150−170 °C with a particle size of 1.25−2 mm and solid loads of about 6.25 g of dry wood/L in the kinetic regime of intrinsic kinetics. The pH of the liquid phase was measured during the reaction. The selectivity of the dissolution and degradation of hemicelluloses was ...

Mixed southern hardwood chips were extracted with an alkaline wood pulping solution called kraft green liquor. This aqueous solution containing mainly sodium carbonate and sodium sulfide was applie...

A new synthetic method for nolatrexed dihydrochloride (thymitaq) has been developed. The synthesis was accomplished in three steps featuring the direct conversion of the starting 4-bromo-5-methylisatin into the methyl anthranilate by potassium peroxydisulfate/sodium methoxide. In the final Ullmann reaction potassium carbonate was employed in place of sodium hydride, and the amount of copper catalysts was significantly reduced. Moreover, sodium sulfide solution was utilized to efficiently remove copper under approximately neutral conditions instead of hydrogen sulfide/methanol under strongly acidic conditions. By means of these modifications, nolatrexed dihydrochloride was ensured to be prepared in good yield and high purity.

A study involving the evaporation−grinding MALDI sample preparation method, MALDI-TOF/TOF CID, and Py-GC/MS is presented to examine the fragmentation mechanisms of poly(p-phenylene sulfide) (PPS). MALDI-TOF/TOF CID fragmentation studies yielded a wealth of information about the mass, structure (linear or cyclic), end-groups, and backbone modifications of the polymer. Additionally, Py-GC/MS experimental data are presented for comparison of the multimolecular free radical reactions in pyrolysis with the unimolecular fragmentation reactions of MS/MS.(1, 2) TOF/TOF CID results indicate that linear PPS undergoes random main chain fragmentation along the polymer backbone and preferentially fragments at bonds adjacent to dibenzothiophene and phenyl end-groups. Cyclic species produce fragment ions similar to linear species. However, the MS/MS precursor ions for cyclic PPS are, by far, the most intense peaks, while the precursor ions for linear species show relatively low intensity. CID fragmentation results are s...

A combination of the evaporation-grinding MALDI-TOF MS sample preparation method with surface-modification techniques is presented for the characterization of intractable poly(p-phenylene sulfide)s (PPS). Studies focus on the relationships between the following experiments: (1) effects of MALDI laser fluence and area of irradiation on model PPS phenyl-capped trimers and cyclics; (2) modification of PPS synthesis conditions; (3) thermal curing of PPS under various atmospheric (N2 and air) and thermal (100−300 °C) conditions; and (4) heated N-methyl-2-pyrrolidone fractionation of high MW PPS (25, 50, 75, and 100 °C). These studies yielded a wealth of information on the mass, structure, and end groups of species generated in the synthesis, postsynthesis modification, and thermal curing of PPS. Furthermore, surface-modified MALDI sample preparation techniques were shown to selectively isolate cyclic species from high-molecular-weight PPS.

This paper presents a preparation route which allows the formation of a poly(phenylene) ionomer containing merely sulfone units (−SO2−) connecting the phenyl rings and in which each phenyl ring is monosulfonated (100% degree of sulfonation). This corresponds to an ion exchange capacity (IEC) of 4.5 mequiv g−1 (equivalent weight of EW = 220 g equiv−1). The preparation succeeded in a two-step process comprising a polycondensation reaction of sulfonated difluorodiphenyl sulfone with sodium sulfide, yielding sulfonated poly(phenylene sulfide sulfone), and the subsequent oxidation to the corresponding sulfonated poly(phenylene sulfone). The polymer was characterized by elemental analysis, NMR, IR, GPC, viscosity measurement, TGA in air and in pure water vapor atmosphere, DSC at low and high temperatures, and ac impedance spectroscopy. Room temperature water absorption isotherms have been determined by equilibrating samples at different relative humidities. Under the chosen reaction conditions, polymers with mo...

A hybrid photocatalytic system, which is based on a mixed-phase cadmium sulfide matrix composed of nanoparticulate cubic-phase CdS (c-CdS) with average particle diameters of 13 nm and a bandgap energy of 2.6 eV, is coupled with bulk-phase hexagonal CdS (hex-CdS) that has a bandgap energy of 2.3 eV and is interlinked with elemental platinum deposits. The resulting hybrid nanocomposite catalysts are photocatalytically efficient with respect to hydrogen gas production from water with visible light irradiation at λ > 420 nm. Rates of H2 production approaching 1.0 mmol-H2 g−1 h−1 are obtained with a c-CdS/Pt/hex-CdS composite photocatalyst, in the presence of a mixed sodium sulfide and sodium sulfite background electrolyte system at pH 14. In contrast, the same composite produces H2 a rate of 0.15 mmol g−1 h−1 at pH 7 in a water-isopropanol solvent system. The relative order of reactivity for the synthesized hybrid catalysts was found to be c-CdS/Pt/hex-CdS > Pt/c-CdS/hex-CdS > Pt/hex-CdS > hex-CdS > c-CdS/hex...

Methyl bromide has been used for decades as a pesticide, primarily as an insecticide. It has also been recently advocated as an excellent agent for the destruction of anthrax spores via fumigation. Related to this use is the need to efficiently destroy methyl bromide safely, once fumigation is complete. This paper describes the selection of a nucleophile for instantaneous decomposition of methyl bromide to destroy methyl bromide in a fumigation vent air stream from an office trailer. Our preliminary data showed that sulfide anion dissolved in water is an exceptionally effective nucleophile for the purpose of CH3Br decomposition. We show data proving the effectiveness of the sodium sulfide aqueous solution accompanied by methyltricaprylylammonium chloride as a phase transfer catalyst for scrubbing methyl bromide present in air.

Reconfigurable and resettable arithmetic functions from a dual-emissive molecule, 1,2-di[5-methoxy-2-(2-pyridiyl)thiazoyl]ethyne (DMPTE), were realized. On the basis of its chemical-sensitive fluorescence, the half-adder is idealized by the introduction of sodium sulfide and trifluoroacetic acid, while the half-subtractor is constructed with sodium hydroxide and trifluoroacetic acid. Each signal of the fluorescent outputs triggered by the chemical inputs is compensated through the proper reset agents, resulting in the initial solution state being restored. Through the reversible control of the fluorescent on-off states, the arithmetic functions are reconfigured and reset. Thus, both the half-adder and the half-subtractor are idealized in a single cell with a successive introduction of chemical inputs.

The reaction of sodium sulfide with chloroauric acid has been surrounded by a controversy over the structure of the resulting product. The original report proposed a Au2S/Au core/shell structure based on strong near-IR resonance and limited transmission electron microscopy. Subsequent reports used the same model without further attempts to determine the structure of the products. With a significant body of experimental work compiled over a period of several years, we have shown that the major product of this reaction is aggregated spherical nanoparticles of gold with a minority component consisting of triangular and rod-like structures. This is in contradiction to the core/shell structures as originally proposed. Recently, there have been additional reports that again suggest a Au2S/Au core/shell structure or irregularly shaped Au nanoparticles as an explanation for the near-IR resonance. To help resolve this issue, we have carried out further experiments to determine how the reaction products may depend ...

Traditional pollution control technologies are able to capture oxidized forms of mercury to some extent; however, they show low efficiency for the control of elemental mercury emissions. This study developed a novel mercury removal technology: injection of sodium tetrasulfide (Na2S4) dissolved in the sodium hydroxide (NaOH) solution in the spray-dryer system. The effects of flue gas temperature and Na2S4 level in flue gas on the mercury removal efficiency were investigated. Na2S4 was decomposed into Na2S (S2-) and elemental S (S0), which reacted with HgCl2 and elemental Hg (Hg0), and HgS was then formed. Under the optimized operation parameters, this technology can simultaneously remove over 88% of HgCl2 and more than 90% of Hg0 from a flue gas stream containing about 400 microg m(-3) Hg0 and 1200 microg m(-3) HgCl2. The increased flue gas temperature (170 degrees C) and the decreased Na2S4-to-Hg mass ratio (S-Hg-R) (2.0) had negative effects on the reactions of gaseous mercury (HgCl2 + Hg0) with ionic sulfur (S2-) and S0. All the experiments were conducted in a full scale hospital-waste incinerator with a capability of 20 tons per day (TPD).

We reported the first synthesis of CdS nanocrystal-polymer transparent hybrids by using polyurethane (PU) grafted onto quantum dots (QDs) CdS nanocrystals. In a typical run, the appropriate amounts of cadmium chloride (CdCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H2O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus's model according to UV-vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystals is about 5 nm. Then, PU-CdS transparent nanocomposites hybrids were synthesized by a two-step reaction. The effect of the different ratios of ME/Cd2+ and H2O/DMF on the resulting particle size of CdS nanocrystals was investigated by UV-vis absorption measurements. FT-IR and TGA characterizations indicate the formation of robust bonding between CdS nanocrystals and the organic ligand. The fluorescence measurement shows that CdS-PU hybrids exhibit good optical properties.

The recently developed protocol for the absolute determination of the various polysulfide species based by 1H NMR was applied to monitor the amount of such ions in alkaline media produced at different conditions. The thermal stability of each individual polysulfide species was also evaluated in temperature ranges representative of a typical alkaline pulping process. Overall, the species, S12-, S22-, S32-, S42-, S52-, and S62- were detected and quantified in all alkaline conditions evaluated. The concentration of sodium sulfide and the temperature were found to have a significant effect on the total amount of polysulfides detected. In summary, the di- and trisulfide anions were found to predominate over the other polysulfide species in all examined experimental conditions. Additionally, the experimental values of Ea for the thermal degradation of polysulfide species correlate with the observed stability of the individual species; i.e., S22- has the highest Ea, followed by S32-.

Reactions in three immiscible liquid phases are attractive, and one of the phases can be the locale of the reaction, which will have a dramatic effect on the product distribution in complex reactions. Thus, converting a bi-liquid (L-L) system into tri-liquid (L-L-L) phases is of considerable scientific and commercial interest. Such systems encounter mass-transfer resistances for transfer across two interfaces and the kinetic analysis becomes difficult. In the case of phase transfer catalysis (PTC), a majority of preparatory and industrial reactions are conducted in two phases. The L-L PTC reactions are conducted under milder conditions, using less-expensive solvents at much faster reaction rates and improved selectivities to desired products. However, the phase transfer catalyst is not recovered but treated as waste, because the quantities are very small and do not contribute much to the expensive product. L-L PTC can be elegantly modified to convert it to L-L-L PTC, to recover and reuse the catalyst and also to enhance selectivity, thereby improving profitability and environmental benefits. 3,4-Dimethyl aniline is a useful starting material for the production of riboflavin (vitamin B2) and also is used as a precursor for many drugs. It can be produced via the reduction of 4-nitro-o-xylene in toluene with aqueous sodium sulfide, using tetrabutylammonium bromide (TBAB) as a catalyst under L-L-L PTC at 80 °C. Comparison between tri- and bi-liquid phases was also conducted, and it was observed that, under L-L-L conditions, the rates of reaction of the formation of 3,4-dimethyl aniline had been dramatically enhanced. The kinetics and mechanism of complex L-L-L PTC processes have been explored in detail. The yield, based on the initial amount of reactant, was >95%, and the selectivity was 100%.

Noncarbonaceous materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups such as amine, amide, thiol, urea, and active additives such as elemental sulfur, sodium sulfide, and sodium polysulfide to examine their potential as sorbents for the removal of elemental mercury (Hg(0)) vapor at coal-fired utility power plants. A number of sorbent candidates such as amine- silica gel, urea- silica gel, thiol- silica gel, amide-silica gel, sulfur-alumina, sulfur-molecular sieve, sulfur-montmorillonite, sodium sulfide-montmorillonite, and sodium polysulfide-montmorillonite, were synthesized and tested in a lab-scale fixed-bed system under an argon flow for screening purposes at 70 degrees C and/or 140 degrees C. Several functionalized silica materials reported in previous studies to effectively control heavy metals in the aqueous phase showed insignificant adsorption capacities for Hg(0) control in the gas phase, suggesting that mercury removal mechanisms in both phases are different. Among elemental sulfur-, sodium sulfide-, and sodium polysulfide-impregnated inorganic samples, sodium polysulfide-impregnated montmorillonite K 10 showed a moderate adsorption capacity at 70 degrees C, which can be used for sorbent injection prior to the wet FGD system.

A conventional dehairing process with sodium sulfide and lime is a major source of the pollution from the tanning industry. In other words, conventional dehairing processes degrade the hair to the extent that it cannot be recovered; thus, these processes become a major contributor to wastewater pollution. In this study, an attempt has been made to develop a lime and sulfide-free dehairing process using a commercial enzyme formulation with the activation of a silicate salt. A dip and pile method of application has been standardized. The amount of enzyme and sodium metasilicate has also been optimized based on complete removal of hair. Enhancement of enzyme activity by the addition of silicate has been demonstrated through activity measurements. Hair removal is found to be complete using scanning electron microscope analysis. Strength and bulk properties of the experimental leathers are comparable to that of control leathers. The process enjoys a significant reduction in chemical oxygen demand (COD) and total solids (TS) by 53 and 26%, respectively. More importantly, the application of enzyme for dehairing results in an 8% area increase in the final leather. Also, the process is proven to be techno-economically feasible.

The importance of sulfur dyeing of cellulosic fibers, particularly cotton, is realized economically throughout the dyeing industry. At the present time, dyeing with sulfur dyes requires the use of various auxiliaries, many of which have adverse effects on the environment. The most damaging of these is the reducing agent sodium sulfide, required to reduce the dye molecules to a water-soluble leuco form to enable adsorption and diffusion into the fiber. In this study, attempts have been made to replace the sodium sulfide used within the sulfur dyeing process with a variety of environmentally friendly reducing sugars. The redox potential of various hexose and pentose monosaccharides and reducing disaccharides was recorded and compared. Subsequently, cotton was dyed with the world's most important sulfur dye, C. I. Sulfur Black 1, using the reducing sugars under alkaline conditions, and compared to dyeings secured by employing commercial sulfide reducing agents. It was observed that reducing sugars gave comparable, and in many cases superior, color strength and wash fastness results, with respect to the commercial sulfide-based reducing agents, which still account for the vast majority of sulfur dyeing processes and that pose significant environmental concern. Employment of reducing sugars in sulfur dyeing could provide a sustainable, nontoxic, biodegradable, cost-effective alternative to sodium polysulfide and sodium hydrogen sulfide. Comparison of the redox potential of reducing sugars against the color strength of the dyeings secured demonstrated that there was an optimum redox potential of around -650 mV for maximum color strength achieved. The same redox potential also conferred the lowest color loss upon washing. These observations were attributed to reduction of the polymeric dye molecules to an optimum size for fiber affinity and diffusion into the fiber, but which would also confer maximum wash fastness upon oxidation.

Two unidentified arsenic metabolites were detected in the liver of rats on a gel filtration column by HPLC inductively coupled argon plasma mass spectrometry after an injection of dimethylarsinic (DMA(V)), dimethylarsinous (DMA(III)), monomethylarsonic (MMA(V)), or monomethylarsonous (MMA(III)) acid. The same arsenicals were also produced in vitro by incubation of DMA(III) in the liver supernatant but not by DMA(V). The two arsenic metabolites eluted at the same retention times as those of the two arsenicals prepared by reaction of DMA(V) with either thiosulfate plus disulfite or hydrogen sulfide or sodium sulfide plus sulfuric acid. The faster and slower eluting products on a gel filtration column were assigned as dimethyldithioarsinic acid (dimethylarsinodithioic acid) (DMTA(V)) and dimethylthioarsinous acid (DMTA(III)) from mass spectrometric data at m/z = 170 and 138 by electrospray ionization mass spectrometry with negative and positive ion modes, respectively. They were prepared selectively by reacting DMA(V) with hydrogen sulfide or sodium sulfide plus sulfuric acid under different reaction conditions. DMA(III) but not DMA(V) was transformed to DMTA(III) and DMTA(V) in the presence of sodium sulfide in vitro, suggesting that DMA(V) is reduced to DMA(III) with hydrogen sulfide, thiolated to DMTA(III), and then further thiolated oxidatively to DMTA(V). Metabolically, it is assumed that DMA(III) is transformed to DMTA(III) in the presence of sulfide ions, and then, DMTA(III) is oxidatively thiolated to DMTA(V). As the chemical species produced by reduction with the Reay and Asher method are DMTA(III) and DMTA(V), and different from DMA(III), the studies carried out with DMA(III) with the Reay and Asher method have to be reexamined.

Silver sulfide nanocrystals have been formed by the conversion of silver thiolate polymers with sodium sulfide in a dual-phase solution preparation. From transmission electron microscopy and laser desorption ionization mass spectrometry, the mean nanocrystalline diameter is estimated to be 5.4 nm. Large-angle X-ray diffraction is qualitatively consistent with the rhombic phase (acanthite) of Ag2S. The removal of the silver thiolate polymer is confirmed by mass spectrometry, and initial results indicate that fractional crystallization may be utilized to separate these large nanocrystalline compounds by their respective core sizes. Optical absorption spectroscopy indicates a band gap of 1.1 eV, which is not shifted appreciably from the bulk value for this direct band gap semiconductor.

We examined the use of room-temperature hydrochloric acid (1-6 M) and salt solutions of magnesium chloride, sodium carbonate, and sodium sulfide for the removal of arsenic from synthetic iron monosulfides and contaminated sediments containing acid-volatile sulfides (AVS). Results indicate that acid-soluble arsenic reacts with H2S released from AVS phases and precipitates at low pH as disordered orpiment or alacranite. Arsenic sulfide precipitation is consistent with geochemical modeling in that conditions during acid extraction are predicted to be oversaturated with respect to orpiment, realgar, or both. Binding of arsenic with sulfide at low pH is sufficiently strong that 6 M HCl will not keep spiked arsenic in the dissolved fraction. Over a wide range of AVS concentrations and molar [As]/[AVS] ratios, acid extraction of arsenic from sulfide-bearing sediments will give biased results that overestimate the stability or underestimate the bioavailability of sediment-bound arsenic. Alkaline solutions of sodium sulfide and sodium carbonate are efficient in removing arsenic from arsenic sulfides and mixed iron-arsenic sulfides because of the high solubility of arsenic at alkaline pH, the formation of stable arsenic complexes with sulfide or carbonate, or both.

Beam house processes (Beam house processes generally mean liming-reliming processes, which employ beam.) contribute more than 60% of the total pollution from leather processing. The use of lime and sodium sulfide is of environmental concern (1, 2). Recently, the authors have developed an enzyme-based dehairing assisted with a very low amount of sodium sulfide, which completely avoids the use of lime. However, the dehaired pelt requires opening up of fiber bundles for further processing, where lime is employed to achieve this through osmotic swelling. Huge amounts of lime sludge and total solids are the main drawbacks of lime. An alternative bioprocess, based on alpha-amylase for fiber opening, has been attempted after enzymatic unhairing. This totally eliminates the use of lime in leather processing. This method enables subsequent processes and operations in leather making feasible without a deliming process. A control experiment was run in parallel using conventional liming-reliming processes. It has been found that the extent of opening up of fiber bundles using alpha-amylase is comparable to that of the control. This has been substantiated through scanning electron microscopic, stratigraphic chrome distribution analysis, and softness measurements. Performance of the leathers is shown to be on a par with leathers produced by the conventional process through physical and hand evaluation. Importantly, softness of the leathers is numerically proven to be comparable with that of control. The process also demonstrates reduction in chemical oxygen demand load by 45% and total solids load by 20% compared to the conventional process. The total dry sludge from the beam house processes is brought down from 152 to 8 kg for processing 1 ton of raw hides.

Size-tunable CdS nanorods have been synthesized via the reaction at low temperature (25−65 °C) of air-insensitive inorganic precursors cadmium acetate and sodium sulfide in an aqueous phase with surfactant. Nonionic pluronic amphiphilic triblock copolymers, (EO)x(PO)y(EO)x, were employed as structure-directing agents. The effects of the (EO)/(PO) ratio, surfactant size, and mole ratio between surfactant and precursors in controlling the diameter and the morphology of the final product were investigated. Transmission electron microscopy (TEM) images show that the diameter of the CdS nanorods synthesized by this method can be controlled by varying the surfactant species, the mole ratio between the inorganic precursors and triblock copolymer, and the reaction temperature. However, if the reaction is refluxed in organic solvent (ethylene glycol and glyme) without surfactant, the morphology of the product will change to microrods with flat ends, dumbbell-shaped microrods, and cotton-ball-like microparticles. T...

We report a new synthesis of colloidal gold(I) sulfide nanoparticles by reacting aqueous solutions of sodium sulfide and sodium gold sulfite. Optical absorption spectra and pH were measured during the reaction. The pH changes from 10.3 to 8.8 immediately after mixing the reactants and very slowly decreases during particle growth. The nanoparticles exhibit a continuous increase in absorption as the photon energy increases from 1 to 5 eV. The optical band gap of the nanoparticles has been estimated from the onset of absorption to be 1.8 ± 0.2 eV. X-ray photoelectron and energy-dispersive X-ray spectroscopy indicate that the composition of the particles is Au2S. The measured S(2p3/2) and Au(4f7/2) binding energies suggest that Au2S has mixed covalent/ionic bonding. Transmission electron microscopy shows that the particles are roughly spherical with an average diameter of 4 nm.

The 6-, 9-, 12-, 15-, 18-, 21-, 24-, and 27-membered unsaturated thiacrown ethers 1-8 were formed by reaction of cis-1,2-dichloroethylene with sodium sulfide in acetonitrile. Crystal structures of 4-8 were determined by X-ray crystallography, and it was found that all sulfur atoms of 5-8 direct to the inside of the ring (endodentate). All of the ORTEP drawings show that there are cavities in these molecules, and the cavity sizes in 4-8 were 1.76, 2.34, 3.48, 4.43, and 5.36 A, respectively. The UV spectra of 4-8 showed absorption maximums at the range of 255-276 nm in acetonitrile, and the absorption maximums of 4-8 were found to shift to longer wavelengths by changing the solvent from acetonitrile to cyclohexane. The cyclic voltammograms of 4-8 indicate that the larger unsaturated thiacrown ethers were oxidized more easily than the smaller systems, and unsaturated thiacrown ethers were oxidized more easily than corresponding saturated systems. The reaction of 4 with silver trifluoroacetate in acetone afforded the colorless complex Ag(I)(C2H2S)5(CF3COO) 9. The crystal structure of 9 was determined by X-ray analysis, and it was found that three of the five sulfur atoms bonded to the silver atom.

The kinetics of the electrochemical deposition and desorption of sulfur monolayers on highly oriented Au(111) and polycrystalline Au electrodes in aqueous solutions containing sodium sulfide was studied by cyclic voltammetry, chronocoulometry, and chronoamperometry. Cyclic voltammetry experiments reveal that underpotential deposition (upd) and stripping of sulfur takes place at two different potentials at polycrystalline Au substrates leading to two oxidative and two reductive peaks. However, sulfur upd consists of only one oxidative and reductive peak at single crystalline Au(111) substrates. Electrosorption valancy measurements and pH dependency showed that the upd of sulfur involved two-electron and one-step mechanism. The charge corresponding to one monolayer of sulfur was determined by cyclic voltammetry and chronocoulometry, indicating a 0.33 coverage. The chronoamperometric results at polycrystalline Au electrodes indicates that deposition takes place in a Langmuir-type mechanism, whereas the strip...

The general study of crystal growth of spherical-like nanoparticles involves monitoring the kinetics during the progress of the reaction. In the case of cadmium sulfide (CdS), cadmium acetate and sodium sulfide are employed as starting reagents that are dissolved in different solvents (ethylene glycol, glyme, diglyme, and trioctylphosphine) to study the solvent effect on monomers, nucleation rates, and the quality of the seeds. Trialkylphosphine oxide (alkyl = ethyl or octyl) is chosen as a surfactant to passivate the surface of CdS nanoparticles. We propose a kinetic approach model to illustrate the unreported time-evolved crystal growth mechanism observed in this case. An experimental value for the diameter of critical volume (Vc), a nanosized volume with a relative minimum surface-volume tension and considered a temporal stable stage (r = 5.7 nm in this case), is derived from transmission electron microscopy images. The size of the nanoparticles made by this synthesis route is tunable by variation of t...

The preparation and electrochemical characterization of graphite electrodes modified with hexadecylpyridinium−bis(chloranilato)−antimonyl(V), [SbVO(CHL)2]Hex, (CMEs) as well as their behavior as electrocatalysts toward the oxidation of sulfide are described. The self-exchange rate constant ko of immobilized [SbVO(CHL)2]Hex and the effect of the surface coverage were evaluated. [SbVO(CHL)2]Hex is a new compound. Synthesis protocol and some identification studies are given. The fabrication of screen-printed electrodes (SPEs) with a mixture of 5% (w/w) [SbVO(CHL)2]Hex/graphite powder in 1.5% (w/v) ethyl cellulose in 2-butoxyethyl acetate is also described. SPEs, poised at +0.08 mV versus Ag/AgCl, at pH 6.5 were utilized for the determination of sulfide in simulated wastewater samples. Interference of various compounds was also tested. The proposed method correlates well with a colorimetric method. Calibration graphs were linear over the range 0.01−0.7 mM sodium sulfide and the CV was 2.8% (n = 8) for 0.1 mM ...

The reactions of sodium sulfide or disulfide with sulfur, when heated, are examined through Raman spectroscopy. It is shown that whatever the composition of the mixtures, the solid sodium sulfide or disulfide transforms into the crystalline alpha-Na(2)S(4) phase in a first step, with alpha- or beta-Na(2)S(2) as an intermediate. The reaction, which proceeds when the sulfur melts, is assumed to be related to the polymerization-depolymerization mechanism responsible for the formation of smaller rings and sulfur chains in molten S(8). This confirms the strong reactivity of the radical sulfur chain molecules. This solid alpha-Na(2)S(4) formed may further react around 200 degrees C with Na(2)S in excess. This solid-state reaction leads to the formation of beta-Na(2)S(2). It is shown that, after the liquid of composition Na(2)S(4) is heated above 400 degrees C, a glass is formed upon cooling. Annealing this glass around 124 degrees C yields a new gamma-Na(2)S(4) crystalline phase where the S(4)(2-) anions have a smaller torsion angle. This new phase is metastable and transforms into the alpha phase upon prolonged heating at 200 degrees C. The solids, formed from heating the mixtures Na(2)S + (n/8)S(8) or Na(2)S(2) + (n'/8)S(8) with n' = n - 1, for n/= 3 are only crystalline beta-Na(2)S(2) or alpha,gamma-Na(2)S(4) and glassy Na(2)S(4), and for 3n4 alpha and gamma-Na(2)S(4) and alpha, beta, gamma, and delta-Na(2)S(5) depending on the heating treatment. For n4, higher polysulfides decompose under crystallization into Na(2)S(5) and sulfur. The liquids formed from these mixtures show the formation of all the S(n)()(+1)(2-) anions although Na(2)S(3) and Na(2)S(6) do not crystallize from these liquids.

Soil and water contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a serious environmental problem at several active and abandoned munitions production facilities. Zero-valent iron (Fe0) can effectively remediate RDX-contaminated soil and water. The objective of this study was to manipulate Eh and pH for enhanced Fe0-mediated destruction of RDX. This was accomplished by monitoring RDX destruction under controlled Eh-pH conditions (Eh: −300 to +150 mV; pH: 2−10). Decreasing Eh and pH increased RDX destruction in aqueous solution. Treating 20 mg of RDX L-1 (90 μM) under a static Eh of −150 mV and pH 7 with 20 g of Fe0 L-1 removed 95% of the RDX within 4 h; no RDX was detected after 8 h. Treating a soil slurry (20% solids; 510 mg RDX kg-1 soil) with 20 g of Fe0 L-1 at an Eh of −150 mV and pH 7 increased RDX destruction by 24% over the unbuffered control and resulted in 99% RDX destruction within 24 h. Adding 4.2 mM sodium sulfide (in lieu of a static Eh) under similar conditions resulted in 9...

A new method for the synthesis of l-2‘,3‘-dideoxyisonucleosides is described. The readily available, optically active C2-symmetric bis-epoxide (2S,4S)-1,2:4,5-diepoxypentane (5) was prepared by a short route from readily available starting materials. The key step of the new synthesis is the opening of 5 with nucleophiles, which proceeds highly regioselectively; e.g., reaction with sodium sulfide affords a 5:1 mixture of the tetrahydrothiophenediol 9a and the tetrahydrothiopyrandiol 14, and reaction with sodium hydroxide gives exclusively the tetrahydrofurandiol 9b via a preferred 5-exo cyclization. These five-membered diols 9a,b can be converted in only four steps into the modified dideoxyuridine and adenosine isonucleosides 4a−c, one of which (4c) has shown good antiviral activity. In addition, we have examined the opening of the analogous six-carbon bis-epoxide, (2S,5S)-1,2:5,6-diepoxyhexane (23), which affords a 3:1 mixture of the hexahydrothiepinediol 24 and the tetrahydrothiopyrandiol 25 with sodium ...