Sulfide Groups Research Articles

Reactivity of tert‐butylperoxyl radical with some phenylthiazolidine derivatives and probucol

AbstractThe hybrid molecule phenylthiazolidine derivatives and probucol were kinetically examined as antioxidants (AOs) in scavenging tert‐butylperoxyl radical (t‐BuOO•) with comparable to the reference AO, butylated hydroxytoluene (BHT). The anti‐t‐BuOO• reactivity of phenylthiazolidine derivatives and probucol was established using the direct kinetic electron paramagnetic resonance (EPR) technique with pulse reactant injection. Absolute values of the bimolecular reaction rate constants and antiradical capacities of the studied compounds were measured from −63 to 0°C. The main antiperoxylradical sites of the compounds under study were revealed.High removal ability of t‐BuOO• by (2‐(4‐hydroxyphenyl)thiazolidine), 4‐[thiazolidin‐2‐yl]benzene‐1,2‐diol, 2‐(4‐hydroxyphenyl)thiazolidine‐4‐carboxylic acid and probucol was connected with the reaction of hydrogen atom abstraction from phenolic OH group.Weaker antiperoxylradical reactivity of 2‐phenylthiazolidine was connected with the slower reaction of hydrogen atom abstraction from benzylic C–H bond in reference to nitrogen and sulfur atoms compared with the phenolic OH group. It is found that sulfide groups had much weaker participation in antiperoxylradical reactivity of the studied compounds. It is concluded that removal of alkylperoxyl radicals by oxidizable phenylthiazolidine derivatives and probucol may partially account for biological activity of their compounds.

Characterization of Oxidation Products from HOCl Uptake by Microhydrated Methionine Anions Using Cryogenic Ion Vibrational Spectroscopy

The oxidation of the amino acid methionine (Met) by hypochlorous acid (HOCl) to yield methionine sulfoxide (MetO) has been implicated in both the interfacial chemistry of tropospheric sea spray aerosols and the destruction of pathogens in the immune system. Here, we investigate the reaction of deprotonated methionine water clusters, Met-·(H2O)n, with HOCl and characterize the resulting products using cryogenic ion vibrational spectroscopy and electronic structure calculations. Capture of the MetO- oxidation product in the gas phase requires the presence of water molecules attached to the reactant anion. Analysis of its vibrational band pattern confirms that the sulfide group of Met- has indeed been oxidized. Additionally, the vibrational spectrum of the anion corresponding to the uptake of HOCl by Met-·(H2O)n indicates that it exists as an "exit-channel" complex in which the Cl- product ion is bound to the COOH group following the formation of the S═O motif.

Enhanced reduction of smelting gypsum by H2S and in-situ DRIFTs investigated on the mechanisms of S-O bond activation

The gypsum from flue gas desulfurization or the neutralization (D/N gypsum) process of acid wastewater, is an industrial by-product in nonferrous metal smelters. The S and Ca sources of D/N gypsum have significant application prospects. However, the S(IV) reduction is difficult due to the electronic inactivity of CaSO4 and the stability of the S-O band. Our experimental results indicated that the start-up temperature of CaSO4 reduced by CH4 is 900 ℃. However, adding H2S gas with a H2S/CaSO4(S/Ca) ratio of 0.2, the start-up temperature of CaSO4 reacted with CH4 decreases to 650 ℃. With the increase of the S/Ca ratio from 0.04 to 0.2, the yield of CaS increased to 94.97%, and the selectivity toward CO2 formation increases to 71.67%. In-situ diffuse reflectance Fourier transformations spectroscopy (in-situ DRIFTs) results indicate that adding H2S generates the new sulfide groups on the surface of CaSO4, resulted from the S(-II) in H2S changing the distribution of valence electrons of O and activating O. Moreover, the density functional theory (DFT) calculation results exhibit that the activation energy for the first O dissociation decreases to 2.89 eV in the presence of H2S. Furthermore, H2S optimized the reaction path of CH4 and improved the selectivity toward CO2 formation. Comparing to 1000 ℃ without H2S, under 800 ℃ with H2S, the consumption of CH4 reduces to 45%, and the CO2 selectivity increases to 71.67%. Thus, we have developed a method of CaSO4 low-temperature reduction and provide a theoretical basis for its application in engineering.

Recent Developments and Perspectives of Cobalt Sulfide-Based Composite Materials in Photocatalysis

Photocatalysis, as an inexpensive and safe technology to convert solar energy, is essential for the efficient utilization of sustainable renewable energy sources. Earth-abundant cobalt sulfide-based composites have generated great interest in the field of solar fuel conversion because of their cheap, diverse structures and facile preparation. Over the past 10 years, the number of reports on cobalt sulfide-based photocatalysts has increased year by year, and more than 500 publications on the application of cobalt sulfide groups in photocatalysis can be found in the last three years. In this review, we initially summarize the four common strategies for preparing cobalt sulfide-based composite materials. Then, the multiple roles of cobalt sulfide-based cocatalysts in photocatalysis have been discussed. After that, we present the latest progress of cobalt sulfide in four fields of photocatalysis application, including photocatalytic hydrogen production, carbon dioxide reduction, nitrogen fixation, and photocatalytic degradation of pollutants. Finally, the development prospects and challenges of cobalt sulfide-based photocatalysts are discussed. This review is expected to provide useful reference for the construction of high-performance cobalt sulfide-based composite photocatalytic materials for sustainable solar-chemical energy conversion.

Selective zirconocene hydride-catalyzed semi-hydrogenation of terminal alkynes

Based on our recent findings in the area of zirconocene hydride catalysis, we have identified a mild and chemoselective strategy for the formal semi-hydrogenation of terminal alkynes utilizing catalytic quantities of Schwartz's reagent or Cp2ZrCl2. This protocol accommodates a variety of functional groups, delivering monosubstituted alkenes bearing ester, nitrile, epoxy, amino, halo, sulfide and hydroxyl groups.

Solid state lithium-ion rechargeable batteries: An overview

Rechargeable solid-state Li-ion batteries have potential for applications in mobile devices and electric vehicles in the near future to meet the growing demand for high energy storage. Research on rechargeable solid-state Li-ion batteries has a long history and has been accelerating recently. Solid electrolytes are the most important component in the all-solid-state batteries. Solid electrolytes can be divided into the following groups: oxide groups (Perovskite Li3.3La0.56TiO3, NASICON LiTi2(PO4)3, LISICON Li14Zn(GeO4)4, and Li7La3Zr2O12 garnets), sulfide groups (Li2S – P2S5 and Li2S – P2S5 – MxS), hydride group (LiBH4, LiBH4–LiX (X=Cl, Br or I), LiBH4–LiNH2, LiNH2, Li3AlH6 and Li2NH), halogen group (LiI, spinel Li2ZnI4 and anti-perovskite Li3OCl), and polymer group (mainly polyethylene). Although electrolytes with good ionic conductivity have been used, the performance of solid-state rechargeable Li-ion batteries is still far behind that of the ones using liquid electrolytes. Along with the development of science and technology, many scientific and technical problems in solid-state rechargeable Li-ion batteries have been discovered. In this review, the major issues of solid-state rechargeable Li-ion batteries will be breifly documented: the interface between the active material (AM) and the solid electrolyte (SE), aging of the solid-solid interface, electrode structure, and fabrication methods.

Halogenated polyethersulfone sulfides

This paper presents the results of a study of random copolyethersulfone sulfides based on 4,4-dichlorodiphenylsulfone, 1,1-dichloro-2,2-di(4-hydroxyphenyl)ethylene, and sodium sulfide. The synthesis of copolyethersulfone sulfides with different ratios of polyethersulfone and polyphenylenesulfone sulfide units was carried out by high-temperature polycondensation by the reaction of nucleophilic substitution in N,N-dimethylacetamide medium and using potassium carbonate as an alkaline agent. The effect of the solvent used on the yield and reduced viscosity of polyethersulfone sulfides was studied. It has been shown that polymers with high reduced viscosity can be obtained in N,N-dimethylacetamide and N,N-dimethylformamide. The growth dynamics of the reduced viscosity of polyethersulfone sulfides was also studied depending on the ratio of sulfone and sulfide groups. The solubility of these polymers in various solvents has been studied.

Crystal structures of (Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide) and its complex with PtII dichloride.

The crystal structures of (Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide), C26H22P2S2 (I), along with its complex with PtII dichloride, di-chlorido[(Z)-(ethene-1,2-di-yl)bis-(di-phenyl-phosphine sulfide)-κ2 S,S']platinum(II), [PtCl2(C26H22P2S2)] (II), are described here. Compound I features P=S bond lengths of 1.9571 (15) and 1.9529 (15) Å, with a torsion angle of 166.24 (7)° between the two phosphine sulfide groups. The crystal of compound I features both intra-molecular C-H⋯S hydrogen bonds and π-π inter-actions. Mol-ecules of compound I are held together with inter-molecular π-π and C-H⋯π inter-actions to form chains that run parallel to the z-axis. The inter-molecular C-H⋯π inter-action has a H⋯Cg distance of 2.63 Å, a D⋯Cg distance of 3.573 (5) Å and a D-H⋯Cg angle of 171° (where Cg refers to the centroid of one of the phenyl rings). These chains are linked by relatively long C-H⋯S hydrogen bonds with D⋯A distances of 3.367 (4) and 3.394 (4) Å with D-H⋯A angles of 113 and 115°. Compound II features Pt-Cl and Pt-S bond lengths of 2.3226 (19) and 2.2712 (19) Å, with a P=S bond length of 2.012 (3) Å. The PtII center adopts a square-planar geometry, with Cl-Pt-Cl and S-Pt-S bond angles of 90.34 (10) and 97.19 (10)°, respectively. Mol-ecules of compound II are linked in the crystal by inter-molecular C-H⋯Cl and C-H⋯S hydrogen bonds.

Room temperature, simple and efficient synthesis and functionalization of aromatic poly(arylene sulfide)s, poly(arylene sulfoxide)s and poly(arylene sulfone)s

Aromatic polysulfides and polysulfones are a large group of sulfur-containing polymers representing an important class of materials with diverse applications, ranging from high performance engineering plastics, gas separation, ultrafiltration, nanofiltration, ion-exchange membranes, and materials for biomedical applications. All these polymers are produced by high temperature nucleophilic substitution reactions of dichlorobenzene with sodium sulfide (PPS) and dichlorodiphenyl sulfone with bis-phenols in the presence of basic catalysts (PAES). In the present work, novel poly(arylene sulfide)s were obtained in nearly quantitative yields, by one-pot, room temperature, metal-free, highly regioselective, non-stoichiometric step-polymerizations of diphenyl sulfide (DPS) with 1,1,1-trifluoroacetone and isatin, in a mixture of trifluoromethanesulfonic acid (TFSA) with CH2Cl2. The polymers obtained were soluble in common solvents. The oxidation of the poly(arylene sulfide)s with H2O2 at room temperature afforded poly(arylene sulfoxide)s and poly(arylene sulfones) with high oxidation selectivity. On heating, sulfoxide groups of the poly(arylene sulfoxide)s are converted into sulfide groups and oxygen, which acts as an expanding agent, is released in the process to form nanofoams with homogeneous pore distribution. Controlled incorporation of hydroxymethyl-, carboxy-, and “click” able allyl- and propargyl- functionalities is carried out by room temperature, post-modification reactions of the polymers bearing reactive oxindole groups.

Effect of Pendant Sulfide and Sulfonyl Groups on the Thermal, Flow, and Antioxidative Properties of Lipid-Based Aliphatic Monoesters

Thermal, flow, and oxidative stability behavior of oleyl oleate monoesters derivatized with sulfur-containing functional groups (sulfide and sulfonyl) suggests that these compounds may be suitable candidates as sustainable alternative base oils to replace mineral oils in lubricant formulations. A robust thiol-ene addition and oxidation synthesis route was utilized to prepare the materials in high yields and high purity with no byproducts. Changes in the functional properties of oleyl oleate are attributable to the enhanced intermolecular forces and irregular conformations introduced by the bulky polar sulfur-containing groups, which introduce steric hindrances and alter phase behavior. The derivatization of oleyl oleate with sulfide and sulfonyl pendant groups resulted in a lower enthalpy of crystallization (10 kJ/mol compared to 76 kJ/mol for oleyl oleate) and an increased viscosity from 16.3 mPa·s to as high as 175.5 mPa·s at 40 °C. The sulfonyl pendant groups imparted higher viscosity to oleyl oleate due to sulfonyl–sulfonyl interactions. The presence of sulfonyl and sulfide pendant groups increased oleyl oleate oxidation onset (Tonox) by 47 and 149 °C, respectively. The sulfide pendant groups converted hydroperoxides as they are formed into non-radical derivatives and thus delayed oxidation. Overall, the sulfide- and sulfonyl-branched oleyl oleate monoesters of this work presented useful thermal transition and viscosity profiles which are competitive with those of mineral oils, making them suitable alternatives for use in lubricant formulations.

MOF-Derived Nickel–Cobalt Sulfide Nanoflakes Wrapped Carbon Nanotubes for Hybrid Supercapacitors

Transition metal sulfide has been regarded as an ideal electrode material for supercapacitors due to its high energy density. However, the poor cyclic stability caused by low electroconductivity seriously limits its practical application. Herein, carbon nanotubes and nickel–cobalt bimetallic organic framework composites were prepared by the in situ growth method and used as precursors to prepare carbon nanotubes/nickel–cobalt bimetallic sulfide (CNTs/Ni–Co–S-3) composites. Benefits from the synergy between the components, CNTs/Ni–Co–S-3, as a positive electrode material, presented an extremely high specific capacity of 734 C g–1 at 1 A g–1 and an improved rate capability. Furthermore, when CNTs/Ni–Co–S served as the positive electrode of the hybrid supercapacitor (CNTs/Ni–Co–S-3//AC HSC), the device provided a competitive energy density of 42.15 Wh kg–1 at the power density of 852 W kg–1 and long-term stability (88.46% of specific capacitance retention for 10000 cycles at 8 A g–1). This synthesis strategy provides a new pathway for further improving the energy density and cyclic stability of metallic sulfide group composite electrodes.

Synthesis, testing, and computational modeling of pleuromutilin 1,2,3-triazole derivatives in the ribosome

Pleuromutilin antimicrobials have given rise to the most recently FDA approved class of antibiotics for systemic human use. In this work, we describe a synthesis, assay, modeling approach to pleuromutilin development for the highly complex bacterial ribosome. Libraries of substituted 1,2,3-triazole derivatives were synthesized at the pleuromutilin C20 position by applying a recent anti-Markovnikov hydroazidation protocol to directly install an azido group, and at the C22 position through established methods. To learn about the interactions of these libraries with the ribosome and assess the potential for subsequent derivatization, an unbiased computational modeling method was used to biochemically rationalize binding modes of the C20 and C22 pleuromutilin derivatives. A pattern emerged where the triazole and its pendant chain, be it off the C20 or C22 position, moved to occupy the space vacated by the C22 sulfide group of clinical pleuromutilin compounds. Subsequent activity testing and comparative ranking of the computationally docked derivatives to the in vitro activity results showed a high predictability rating for the C22 substituted compounds. These combined investigations reveal potential restrictions and sites for expansion, paving the way for the development of future pleuromutilin derivates and other ribosome targeting antibiotics.

Chain length effects of phenylene sulfide modifiers on selective acetylene partial hydrogenation over Pd catalysts

We recently reported that polymer chains with phenylene sulfide moieties can efficiently modify the Pd catalyst surface, enabling selective partial hydrogenation of acetylene under ethylene-rich conditions. In the present study, we synthesized oligomeric and polymeric phenylene sulfides with tailored molecular sizes to systematically investigate the catalytic effect of chain length of organic modifiers. The results showed that the increased chain length of the modifiers is beneficial for improving the acetylene partial hydrogenation selectivity by inhibiting adsorption and full hydrogenation of ethylene. This was attributed to the fact that modifiers with a greater number of sulfide groups per molecule can bind more efficiently to the Pd surface for entropic reasons (chelate effect) and thus better inhibit ethylene adsorption. In contrast, the adsorption of acetylene to Pd was nearly unaffected by the presence and size of the modifiers owing to its stronger binding ability and small kinetic diameter. Modifiers with larger chain lengths were also advantageous in improving long-term catalyst stability because of their higher thermochemical stability and greater ability to inhibit the formation of carbonaceous deposits. The present results showed that polymers can act as more efficient and long-lasting selectivity modifiers than commonly used small organic molecules.

OPPS Fibers with High Temperature Resistance and Excellent Antioxidant Properties by an Oxidation Method.

Polyphenylene sulfide (PPS) fiber products have been widely used for separation and filtration in harsh environments due to their excellent chemical resistance and relatively economical price. However, the poor temperature and weak oxidation resistance of PPS significantly shorten its service life under high temperature and strong oxidation environments. Herein, we report a type of oxidation-modified PPS (OPPS) fibers with excellent high temperature and oxidation resistance. This is achieved by oxidizing the thioether sulfide groups in PPS molecular chains into sulfoxide and sulfone groups and cross-linking the intermolecular chains. Both experiments and density functional theory (DFT) calculations indicate that hypochlorous acid (HClO) molecules can rapidly oxidize the PPS fiber surface. In addition, molecular dynamics (MD) simulations prove that there are strong hydrogen bonds and van der Waals interactions between HClO molecules and OPPS molecular chains, which promote the penetration of HClO molecules into the interior of the fiber to complete the layer-by-layer oxidation. The prepared OPPS-20 fibers exhibit excellent structural stability under high temperature and strong oxidant environments. Impressively, the OPPS-20 nonwoven filter still exhibits a high dust filtration efficiency of 99.95% after aging at 320 °C for 12 h, and the corresponding pressure drop is 24 Pa. In addition, the OPPS-20 nonwoven filter also maintains excellent filtration performance after aging in 60% HNO3 solution for 12 h, and the filtration efficiency and pressure drop are 99.96% and 29 Pa, respectively. This work demonstrates that the novel OPPS fibers have excellent application prospects in the field of separation and filtration in harsh environments.

Oxidation of methionine-derived 2-hydroxyalkanoate unit in biosynthesized polyhydroxyalkanoate copolymers

In this study, 2-hydroxy-4-methylthiobutyrate (2H4MTB)-containing polyhydroxyalkanoate (PHA) copolymers were biosynthesized using methionine as the 2H4MTB precursor. 2H4MTB is a novel monomer unit that contains a sulfur atom in its side chain. The 2H4MTB-containing PHA was biosynthesized by functionalizing the leucine degradation and PHA synthesis pathways in recombinant Escherichia coli. The 2H4MTB fraction in the PHA copolymer was increased up to 30.6 mol% by increasing the methionine concentration in the medium. Using purified polymers containing 10.9 mol% 2H4MTB unit, the sulfide group of the 2H4MTB side chain was oxidized with hydrogen peroxide or peracetic acid, which resulted in the conversion of sulfide to sulfoxide and sulfone groups. The oxidized polymer was relatively hydrophilic, as revealed by water contact angle measurements, and swelled slightly when soaked in water. These results suggest that the 2H4MTB unit can be used as an oxidation site to impart hydrophilicity to the PHA copolymers.

Correlation Analysis and Regression Fitting of Multiple Sulfide Aging Characteristic Parameters

The corrosion of transformers by multiple sulfides seriously affects the safe operation of transformers. However, there is a lack of quantitative characterization of the extent to which temperature and oxygen as well as changes in sulfide species affect the aging of oil–paper insulation. In this study, the aging characteristics of oil–paper insulation systems were analyzed in terms of the moisture in the oil, moisture in the paper, acid value, and furfural in the presence of multiple sulfides, where the temperature and the oxygen concentration are used as independent variables. A strong positive correlation between the acid value and the furfural obtained by means of Spearman’s correlation analysis. The acid value and furfural content in the oil were then analyzed and compared according to a nonparametric test, and it was found that both the oxygen changes and the temperature changes had a relatively obvious effect on the acid value in the oil. The effect of the temperature change on the furfural was greater than the effect of the oxygen change on the furfural. Finally, a multiple linear regression analysis was performed for the change in the acid value of the oil with the change in the oxygen content and temperature to obtain the linear fitting formulas for the effects of the time, temperature, oxygen content percentage, and sulfide groups on the acid value. This study can be used to quantify the magnitude of the influences of the oxygen, temperature sulfide groups, and other factors on the aging characteristic parameters of the oil–paper insulation system and to provide a certain reference for studying the quantitative characterization of the sulfur corrosion degree by using the change in the acid value in oil.

Study on Modified Liquid Polysulfide Rubber Bimetallic Salt-Spray-Resistant Epoxy Coatings

In this study, liquid polysulfide rubber was modified by silane coupling agent. New kinds of anti-corrosion coatings with salt spray resistance and strong adhesion to the steel substrate were obtained using the modified liquid polysulfide rubber, bimetallic filler, carbon nanotubes, and epoxy resin. Infrared and nuclear magnetic resonance confirmed the preparation of new modified liquid polysulfide rubber through coupling reaction between the epoxy group of silane compound and the sulfide group of the liquid polysulfide rubber. A 1440 h neutral salt spray test showed the coating to be completely free of rust and blisters. The corrosion diffusion width of the scribed area was only 1.7 mm. In addition, in a 3.5% by weight NaCl solution, the coating shows no blistering and no corrosion phenomena compared with zinc-rich epoxy paints (the added zinc content was only 28.6%). These tests confirmed that the new coating had a dense microstructure, strong adhesion to the steel substrate, good corrosion resistance, and anti-blister performance. The performance indicates that the coatings have potential for use in the atmosphere and underwater, which provides a better choice for long-term protection of marine projects such as ships, wharves, offshore platforms, and wind power structures.

PLATE TECTONICS AS A TOOL FOR GLOBAL SCREENING OF MAGMATIC ARCS AND PREDICTIONS FOR RELATED PORPHYRY DEPOSITS

Abstract The formation of most mineral deposits is closely linked to a geodynamic context—for example, the association of porphyry Cu-Au-Mo deposits with subduction and development of volcanic arcs. This paper proposes a new approach to the global screening of volcanic arcs and their duration, as a predictive method for a mineral systems-based approach (e.g., discovery of potential porphyry occurrences). The method utilizes geospatial and temporal analytics run on a combination of large global data sets and a global plate tectonic model (covering the time period 600 Ma to present) containing plate boundaries. The method involves (1) calculating present-day arc volcano-to-trench distances and obtaining average volcanic-arc widths in both continental and intraoceanic settings, (2) applying these values to the paleotrenches contained in the plate tectonic model on 53 time intervals spread throughout the Phanerozoic, (3) unreconstructing the results back to present day, and (4) summing up all magmatic arc occurrences using their cumulative durations. This results in a spatiotemporal model of the total cumulative duration of magmatic arc activity at the global scale, back to 600 Ma, that is updatable and can serve as a proxy to predict porphyry deposit likelihood. The model output is tested against a porphyry copper occurrence data set to validate the approach as a predictive proxy for arc-related porphyry deposits. The alignment of the model results with data control is high for most geologic time periods throughout the Phanerozoic—up to 90% in the case of buffered (1σ) magmatic arcs and up to 100% in the case of buffered magmatic arcs with an additional search distance (2σ). Recent advances in plate tectonic model quality and detail now offer a higher level of precision and confidence than ever before and enable tools for the prediction and screening of porphyry deposit locations, as well as opening the potential to screen for other geodynamic context-dependent commodities (e.g., orogenic gold, volcanogenic massive sulfide, or Ni and platinum group element-sulfide deposits), particularly in the search for poorly exposed or subsurface orebodies.

Acute sulfide exposure induces hemocyte toxicity and microbiota dysbiosis in blood clam Tegillarca granosa.

Sulfide are widely accumulated in aquatic environments under anaerobic conditions, which cause health problems of aquatic animals, yet their toxic effects to benthic bivalves are not well understood. We investigated the effects of sulfide on innate immunity of the blood clam Tegillarca granosa. Immunity-related indicators and hemolymph microbiota were investigated in the clams exposed to sulfide (via 10, 100 and 1000 μmol/L of Na2S) over a 7-day period. The results showed that cellular immune responses in T. granosa were affected by exposure to high sulfide concentration (1000μmol/L Na2S), as indicated by total counts of hemocytes (THC), cell viability, ROS levels and phagocytic activities, suggesting that sulfide stress induces T. granosa more vulnerable to pathogen challenges. In addition, the Na2S-induced stress also reshaped the hemolymph microbial community structure of T. granosa that some original genera decreased, such as Lactobacillus, Desulfovibrio and Akkermansia; some genera increased, such as Vibrio and Pseudoalteromonas in sulfide stress group. Sulfide exposure promoted the proliferation of opportunistic pathogen and reduced the diversity of microbial community in the hemolymph of T. granosa. In summary, sulfide stress had marked hemocytotoxicity, reduced immune-cell activity and increased bacterial infections in the blood clam.

Nitric Acid Promoted Metal-Free Bromothiolation of Internal Alkynes with Hydrobromic Acid and Disulfides

AbstractA novel, metal-free bromo-thiolation of internal alkynes with hydrobromic acid and disulfides has been developed. The reaction is promoted by commercial-grade nitric acid and is used to construct a series of unexplored β-bromoalkenyl sulfides in moderate to good yield. Most products were obtained with high stereoselectivity as syn-configured tetrasubstituted alkenes. Both sulfide groups of the disulfide reagent were used in this method.