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Elemental Sulfur (elemental + sulfur)

Distribution by Scientific Domains

Chemistry	74%
Earth and Environmental Science	12%
Life Sciences	9%

Distribution within Chemistry

Organic Chemistry	29%
General & Introductory Chemistry	8%

Selected Abstracts

Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

ELECTROANALYSIS, Issue 7 2008
Robert Piech
Abstract New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12,mm2, both electrodes are characterized by very good surface reproducibility (,2%) and long-term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1,2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16,ng L,1 to 4.8,,g L,1 for Hg(Cu)FE, and up to 6.4,,g L,1 for Hg(Ag)FE (tacc=15,s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and tacc=60,s are as low as 14,ng L,1 for Hg(Cu)FE and 4,ng L,1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water. [source]

Quantitative Recovery of Elemental Sulfur and Improved Selectivity in a Chromium-Reducible Sulfur Distillation

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2009
Jens Gröger
soufre réductible par le chrome; CRS; soufre élémentaire; selectivité; efficacité de distillation Chromium-reducible sulfur (CRS) distillations are intended to recover only reduced inorganic sulfur compounds (RIS) including elemental sulfur. However, the quantitative recovery of elemental sulfur is not ensured in common CRS-distillations. The new method presented here was designed to remedy this deficiency. An increase in ethanol concentration assured the quantitative recovery of elemental sulfur in various forms and, in addition, all other RIS-compounds were quantitatively recovered. Furthermore, the selectivity of the procedure was improved by an additional filtration step to eliminate zinc particles from the Cr(II)-solution. Thus, the recovery of sulfates and organic sulfur compounds was significantly decreased by a factor of up to 35, depending on the compound analysed. Exhaustive testing with a variety of pure phases, rock and soil samples demonstrated the precision and accuracy of the new method. The new protocol eliminated the constraints of previous procedures. The improved distillation efficiency for elemental sulfur ensured the quantitative recovery of all RIS-compounds in a single-step distillation. Des distillations du soufre réductible par le chrome (CRS) ont été effectuées afin de récupérer uniquement les composés soufrés inorganiques (RIS: reduced inorganic sulfures) dont le soufre élémentaire. La procédure classique de distillation CRS ne permet pas néanmoins la récupération totale du soufre élémentaire. Une nouvelle méthode, présentée ici, a été développée pour remédier à ce problème. L'augmentation de la concentration en éthanol assure la récupération totale du soufre élémentaire sous différentes formes et, de plus, celle de tous les autres composés RIS. La sélectivité de la procédure a été améliorée par l'ajout d'une étape de filtration, qui élimine des particules de zinc provenant de la solution Cr(II). Ceci a entraîné une diminution jusqu'à un facteur 35 du taux d'extraction des sulfates et des composés soufrés organiques, selon les composés analysés. Des tests extensifs sur différentes phases pures et des échantillons de roches et de sols ont montré la précision et la justesse de cette nouvelle méthode. Le nouveau protocole élimine les contraintes des procédures passées. L'amélioration de l'efficacité de cette distillation concernant le soufre élémentaire garantit une récupération fiable de tous les composés RIS par une distillation en une seule étape. [source]

Activation of Elemental Sulfur by Electrogenerated Cyanomethyl Anion: Synthesis of Substituted 2-Aminothiophenes by the Gewald Reaction

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2008
Marta Feroci
Abstract The activation of elemental sulfur (S8) has been achieved by means of electrogenerated cyanomethyl anion [easily obtained by galvanostatic reduction from acetonitrile/tetraethylammonium hexafluorophosphate (MeCN-Et4NPF6)]. The "activated" sulfur reacted with ylidenemalononitriles to give substituted 2-aminothiophenes in very high yields. This variation of the Gewald reaction has been carried out using only catalytic amounts of electricity and supporting electrolyte. A proposed mechanism for the interaction between S8 and cyanomethyl anion is described. [source]

ChemInform Abstract: An Efficient Synthesis of 1,2-Dithiolanes and 1,2,4-Trithiolanes by the Reaction of Phosphorus Ylides with Elemental Sulfur.

CHEMINFORM, Issue 12 2001
Kentaro Okuma
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Elemental sulfur: Toxicity in vivo and in vitro to bacterial luciferase, in vitro yeast alcohol dehydrogenase, and bovine liver catalase

ENVIRONMENTAL TOXICOLOGY, Issue 4 2004
Anolda, etkauskait
Abstract The aim of this research was to analyze the effects and the modes of action of elemental sulfur (S0) in bioluminescence and respiration of Vibrio fischeri cells and the enzymes crude luciferase, pure catalase, and alcohol dehydrogenase (ADH). Metallic copper removed sulfur and reduced the toxicity of acetone extracts of sediment samples analyzed in the bioluminescence test. The sulfur inhibition of cell bioluminescence was noncompetitive with decanal, the luciferase substrate; reversible, with maximum toxicity after 15 min (EC50 = 11.8 ,g/L); and almost totally recovered after 2 h. In vitro preincubation of crude luciferase extract with sulfur (0.28 ppm) weakly inhibited bioluminescence at 5 min, but at 30 min the inhibition reached 60%. Increasing the concentration of sulfur in the parts per million concentration range in vitro decreased bioluminescence, which was not constant, but depended on exposure time, and no dead-end/total inhibition was observed. The redox state of enzymes in the in vitro system significantly affected inhibition. Hydrogen peroxide restored fully and the reducing agent dithiothreitol, itself toxic, restored only partially luciferase activity in the presence of sulfur. Sulfur (5.5 ppm) slightly inhibited ADH and catalase, and dithiothreitol enhanced sulfur inhibition. High sulfur concentrations (2.2 ppm) inhibited the bioluminescence and enhanced the respiration rate of V. fischeri cells. Elemental sulfur data were interpreted to show that sulfur acted on at least a few V. fischeri cell sites: reversibly modifying luciferase at sites sensitive to/protected by oxidative and reducing agents and by affecting electron transport processes, resulting in enhanced oxygen consumption. Sulfur together with an enzyme reducing agent inhibited the oxidoreductive enzymes ADH and catalase, which have SH groups, metal ion cofactors, or heme, respectively, in their active centers. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 372,386, 2004. [source]

Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

Elemental sulfur: Toxicity in vivo and in vitro to bacterial luciferase, in vitro yeast alcohol dehydrogenase, and bovine liver catalase

Mono-, Bi-, Tri- and Tetranuclear Palladium(II), Copper(I), and Gold(I) Complexes of Morpholine- and N -Methylpiperazine-Functionalized Cyclodiphosph(III)azans, cis -[(tBuN-,)2(PNC4H8X)2] (X = O, NMe)

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2010
Maravanji S. Balakrishna
Abstract Bis(amido)cyclodiphosphazanes, cis -[(tBuN-,)2(PNC4H8O)2] (2) and cis -[(tBuN-,)2(PNC4H8NMe)2] (3) were synthesized by treating the corresponding amines with cis -[ClP(tBuN-,)2PCl] (1). The stoichiometric reactions of 2 or 3 with elemental sulfur and selenium afforded the bis-chalcogenides, cis -[(tBuN-,)2(P(E)NC4H8X)2] (X = O, E = S; 4, X = NMe, E = S; 5, X = O, E = Se; 6, X = O, E = Se; 7). The reactions of 2 or 3 with [PdCl2(SMe2)2] produced exclusively the mononuclear trans -[PdCl2{(tBuN-,)2(PNC4H8X)2}2] (X = O; 8, X = NMe; 9), whereas the reactions with [Pd(,-Cl)(,3 -C3H5)]2 afforded the bimetallic complexes [{PdCl(,3 -C3H5)}2{(tBuN-,)2(PNC4H8X)2}] (X = O; 10, X = NMe; 11) in good yield. Treatment of 2 or 3 with [AuCl(SMe2)] in 1:1 and 1:2 molar ratios yielded the mono- and binuclear complexes, [{AuCl(tBuN-,)2(PNC4H8O)2}] (X = O; 12, X = NMe; 13), [{AuCl}2{(tBuN-,)2(PNC4H8O)2}] (X = O; 14, X = NMe; 15), respectively. The PdII (8) and AuI (12) complexes were used as metallo-ligands to prepare homo- and heterometallic complexes, trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2{Pd(,3 -C3H5)Cl}2] (16), trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2(AuCl)2] (17), and [Cu(CH3CN)(,-Cl)2Cu(CH3CN){(tBuN-,)2(PNC4H8O)2}2(AuI)2](18). The crystal structures of 2, 4, 7,9, 14, 15, and 18 were established by single-crystal X-ray diffraction studies. [source]

Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007
Urs Fischbach
Abstract The tetradendate phosphane tris(5H -dibenzo[a,d]cyclohepten-5-yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5-chloro-5H -dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X-ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky ,1 -phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (, = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M,C=Ctrop) and ,(31P) decreases with increasing M,C=Ctrop in the order 9 (, = 260 ppm) > 7 (, = 196 ppm) > 6 (, = 135 ppm) > 3 (, = ,30.9 ppm). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Syntheses and Coordination Chemistry of Aminomethylphosphine Derivatives of Adenine

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003
Qingzhi Zhang
Abstract Two aminomethylphosphane derivatives of adenine 9-(2-{bis[(diphenylphosphanyl)methyl]amino}ethyl)adenine (La) and 9-(3-{bis[(diphenylphosphanyl)methyl]amino}propyl)adenine (Lb) were synthesised. Oxidation of La and Lb with H2O2, elemental sulfur or elemental selenium led to the corresponding oxidized products 4a/b,6a/b. Both La and Lb behave as didentate ligands towards late transition metals. Reaction of La or Lb with [MX2(cod)] (M = Pd, Pt; X = Cl, Me) gave chelate complexes 7a/b,10a/b. Reaction of La or Lb with [AuCl(tht)] or [{RuCl(,-Cl)(p -MeC6H4iPr)}2] gave the didentate bridging complexes 11a/b and 12a. All compounds have been fully characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy, and EI/CI/FAB mass spectrometry. 1H{31P} NMR and 1H- 13C correlation experiments were used to confirm the spectral assignments where necessary. Two compounds were structurally characterised by X-ray crystallographic analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Propyne Iminium Salts and Phosphorus(III) Nucleophiles: Synthesis of (3-Morpholinoallenyl)phosphanes and -phosphane Oxides or 1-(Morpholinopropargyl)phosphanes and -phosphonates

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003
Martin Reisser
Abstract Treatment of 4-(1,3-diphenyl-l-propynylidene)morpholinium triflate (1a) with the neutral phosphorus nucleophiles Me3Si,PPh2, Me3Si,P(Ph)C5H11, and Me3SiO,PPh2 affords (3-morpholinoallenyl)phosphanes 4 and 5 and (3-morpholinoallenyl)phosphane oxide 11, respectively. In contrast to these conjugate addition reactions at the ambident propyne iminium moiety of 1a, nucleophilic attack by Me3Si,PEt2 and Me3SiO,P(OEt)2 takes place at the iminium function and gives (1-morpholinopropargyl)phosphane 6 and (1-morpholinopropargyl)phosphonate 12, respectively. Propyne iminium salt 1b reacts with Me3Si,PPh2 to form (3-morpholino-1,3-butadienyl)phosphane oxide 8. The bis(donor)-substituted allene 4 is transformed by oxidation of the phosphorus substituent into the push-pull substituted allenylphosphane oxide 11. Treatment of allene 4 with elemental sulfur results in the formation of betaine 16, which undergoes [3+2] cycloaddition reactions with acetylenic esters to afford 5-benzylidene-4,5-dihydrothiophenes 17 and 18. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

A novel NADPH-dependent oxidoreductase with a unique domain structure in the hyperthermophilic Archaeon, Thermococcus litoralis

FEMS MICROBIOLOGY LETTERS, Issue 1 2008
András Tóth
Abstract Thermococcus litoralis, a hyperthermophilic Archaeon, is able to reduce elemental sulfur during fermentative growth. An unusual gene cluster (nsoABCD) was identified in this organism. In silico analysis suggested that three of the genes (nsoABC) probably originated from Eubacteria and one gene (nsoD) from Archaea. The putative NsoA and NsoB are similar to NuoE- and NuoF-type electron transfer proteins, respectively. NsoC has a unique domain structure and contains a GltD domain, characteristic of glutamate synthase small subunits, which seems to be integrated into a NuoG-type sequence. Flavin and NAD(P)H binding sites and conserved cysteines forming iron,sulfur clusters binding motifs were identified in the protein sequences deduced. The purified recombinant NsoC contains one FAD cofactor per protein molecule and catalyzes the reduction of polysulfide with NADPH as an electron donor and it also reduces oxygen. It was concluded that the Nso complex is a new type of NADPH-oxidizing enzyme using sulfur and/or oxygen as an electron acceptor. [source]

Quantitative Recovery of Elemental Sulfur and Improved Selectivity in a Chromium-Reducible Sulfur Distillation

The Synthesis, Characterisation, and Reactivity of Some Polydentate Phosphinoamine Ligands with Benzene-1,3-diyl and Pyridine-2,6-diyl Backbones

HELVETICA CHIMICA ACTA, Issue 10 2003
Nermin Biricik
The polydentate phosphinoamines 1,3-{(Ph2P)2N}2C6H4 and 2,6-{(Ph2P)2N}2C5H3N have been prepared in a single step from the reaction of the amines 1,3-(NH2)2C6H4 or 2,6-(NH2)2C5H3N with Ph2PCl in presence of Et3N (1,:,4,:,4 molar ratio) in CH2Cl2. Reaction of 1,3-{(Ph2P)2N}2C6H4 or 2,6-{(Ph2P)2N}2C5H3N with elemental sulfur or selenium in CH2Cl2 affords the corresponding tetrasulfide or tetraselenide, respectively, in good yield. The complexes [1,3-{Mo(CO)4(Ph2P)2N}2(C6H4)] and [2,6-{Mo(CO)4(Ph2P)2N}2(C5H3N)] were prepared from the reaction of these phosphinoamines with [Mo(CO)4(nbd)] (nbd=norbornadiene) in toluene, and the structure of the latter complex has been determined by single-crystal X-ray diffraction analysis. [source]

Reaction of N -thioamido amidines with phosphoramide derivatives: Synthesis of 2-substituted-1,3,5,2-triazaphosphorines

HETEROATOM CHEMISTRY, Issue 5 2009
Noureddine Raouafi
The reaction of N -thioamido amidines 1 with tris(dimethylamino)phosphine or bis(diethylamino)phenylphosphine in refluxing toluene leads to the 1,3,5,2,3 -triazaphosphorines 2 and 3, respectively. The condensation results in the release of two molecules of dialkylamine. The sulfuration of the trivalent phosphorus atoms was achieved by the reaction with elemental sulfur, followed by heating in toluene. The structure of the triazaphosphorines 2 and 3 and their thione derivatives 4 and 5 were readily elucidated by means of 1H, 13C, and 31P NMR spectroscopy and mass spectrometry. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:272,277, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20546 [source]

Chalcogenation reactions of a stable ferrocenyldiphosphene: Formation of thia-, selena-, and telluradiphosphiranes,

HETEROATOM CHEMISTRY, Issue 5 2008
Noriyoshi Nagahora
The reactions of TbtPPTbt (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) with elemental sulfur and selenium in the presence of triethylamine resulted in the formation of the corresponding thia- and selenadiphosphiranes in 71% and 65%, respectively, whereas the tellurization reaction was unsuccessful probably due to the steric reason. On the other hand, treatment of TbtPPFc (Fc = ferrocenyl) with elemental sulfur, selenium, and tributylphosphine telluride afforded the corresponding thia-, selena-, and telluradiphosphiranes in 84%, 88%, and 66% yields, respectively. The molecular structures of these three-membered heterocyclic compounds were confirmed by spectroscopic analysis. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:443,449, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20449 [source]

An Efficient Combined Electrochemical and Ultrasound Assisted Synthesis of Imidazole-2-Thiones

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009
Marta Feroci
Abstract The electrochemical reduction of 1,3-dialkylimidazolium ionic liquids gave the corresponding N-heterocyclic carbenes that, after reaction with elemental sulfur and ultrasound irradiation, yielded 1,3-dialkylimidazole-2-thiones in very high yields. The reaction is very clean, produces no side-products and avoids the use of any other added reagent. [source]

Activation of Elemental Sulfur by Electrogenerated Cyanomethyl Anion: Synthesis of Substituted 2-Aminothiophenes by the Gewald Reaction

Oxidation of biologically produced elemental sulfur under neutrophilic conditions,

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2010
Marc Fortuny
Abstract BACKGROUND: Previous research on a biotrickling filter for the removal of high loads of H2S showed that accumulation of elemental sulfur (S0) when dealing with high H2S concentrations could lead to reactor clogging. Since S0 can also serve as substrate for sulfur-oxidising bacteria, this study investigates the biological oxidation of S0 as a remediation strategy. RESULTS: Results indicated that biological oxidation of S0 inside a clogged biotrickling filter occurred at a comparable rate to those reported for stirred tank reactors. When biologically produced dried and powdered S0 was manually added as a substrate in stirred tank reactor experiments, significantly lower S0 oxidation rates were found compared to those for biological S0 freshly produced in situ. It was speculated that either the powdered S0 particle size or the surface properties hindered S0 bioavailability even in a well-stirred environment. Respirometric experiments with the same powdered S0 and acetone-dissolved S0 confirmed that biological oxidation of S0 was basically limited by the solid S0 bioavailability. CONCLUSIONS: Therefore, results showed that S0 oxidation basically depends on S0 bioavailability and that Sulfate volumetric production rates as high as 3.48 mmol SO42, h,1 L,1 can be achieved inside a clogged biotrickling filter probably due to the high biomass retention capacity. Overall, the results indicate that biological oxidation of S0 can be considered a suitable strategy for unclogging bioreactors clogged with S0. Copyright © 2010 Society of Chemical Industry [source]

Removal of H2S and volatile organic sulfur compounds by silicone membrane extraction

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009
I. Manconi
Abstract BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10,6 m s,1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10,6 m s,1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA, as extractant (5.81 × 10,7 m s,1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10,6 m s,1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA, was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry [source]

Light emitting diodes and an infrared bulb as light sources of a fixed-film tubular photobioreactor for conversion of hydrogen sulfide to elemental sulfur

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2005
Murtuza A Syed
Abstract The effect of light quality on the performance a fixed-film continuous-flow photobioreactor for removal of hydrogen sulfide from synthetic industrial wastewater and conversion of it to elemental sulfur was investigated. Sixteen 150 mm long and 1.6 mm internal diameter (id) Tygon tubes formed the active part of the reactor. At the same light intensity, reactor performance in terms of optimal sulfide loading rates was compared between an infrared bulb and light emitting diodes (LEDs). The LEDs provided light within the peak absorption wavelength range of green sulfur bacteria (GSB) and were used as a light source for the GSB with the goal of reducing the cost of the required light. Though the reactor sustained higher sulfide loading rates using LEDs than when using an infrared bulb at equal light intensities, the infrared bulb has the potential to be more efficient overall. Copyright © 2004 Society of Chemical Industry [source]

Synthesis of [35S]aryl sulfonyl chlorides from [35S]elemental sulfur

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2005
Michael A. Wallace
Abstract A new synthetic methodology that captures electrophilic 35S8 with aryl Grignard reagents or lithiates provides entry to a wide variety of [35S]aryl sulfonyl chlorides upon oxidation and chlorination. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Separation and determination of small amounts of sulfur in technical thiophanate-methyl by reversed-phase high-performance liquid chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9-10 2003
R. Nageswara Rao
Abstract A simple and rapid reversed phase high-performance liquid chromatographic method for separation and determination of elemental sulfur in technical thiophanate-methyl using a reversed-phase C18 column and methanol-water-tetrahydrofuran (90 : 8 : 2 v/v/v) as eluent with UV detection at 254 nm has been developed and validated with respect to accuracy, precision, specificity, linearity range, and limits of detection and quantification. The method was found to be suitable not only for detection but also determination of elemental sulfur at levels of 5×10,9 g. [source]

Comparing the dynamic behaviour of several rubbers filled with silanized silica nanofiller

POLYMER INTERNATIONAL, Issue 2 2009
Saeed Ostad Movahed
Abstract BACKGROUND: The effect of the same amount of precipitated silica nanofiller on the curing and dynamic properties of different rubbers, including natural rubber (NR) without and with the addition of elemental sulfur (NR with S), synthetic polyisoprene (IR), polybutadiene (BR) and poly(styrene- co -butadiene) copolymer (SBR), was investigated. The silica surfaces were pre-treated with bis(3-triethoxysilylpropyl)tetrasulfane (TESPT) to chemically bond the silica to the rubber. The rubbers were primarily cured by using sulfur in TESPT with the addition of optimum accelerator (TBBS) and activator (ZnO), which helped to form sulfur chemical bonds between the rubber and filler. RESULTS: Cure properties, Mooney viscosity, glass transition temperature, bound rubber and crosslink density along with dynamic properties of the filled rubbers, including tan ,, loss modulus (G,) and storage modulus (G,), were measured as a function of double oscillation amplitude (DSA) from 15 to 1000 µm, temperature from ,130 to 100 °C and frequency from 1 to 100 Hz. The results with emphasis on potential for tyre tread applications are discussed. It emerged that SBR along with BR filled rubbers had the highest rolling resistance while IR filled rubber had the least. Moreover, it was found that SBR filled rubber had the best skid resistance and BR filled rubber the worst. CONCLUSION: Interestingly, the variation of G, with DSA showed a complicated behaviour for different filled rubbers. It emerged that in some DSA ranges the Payne effect was observed, and in the remaining ranges increments of G, with DSA were seen. Because the bound rubber of most of the filled rubbers was more than 92%, there should be another predominant mechanism in the systems studied rather than simply de-agglomeration or filler network breakdown, which is proposed by the Payne model. In addition, the nanoscale of the filler may be effective for this behaviour. Copyright © 2008 Society of Chemical Industry [source]

Synthesis and anticancer activity of chalcogenide derivatives and platinum(II) and palladium(II) complexes derived from a polar ferrocene phosphanyl,carboxamide

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2010
í Schulz
Abstract The polar phosphanyl-carboxamide, 1,-(diphenylphosphanyl)-1-[N -(2-hydroxyethyl)carbamoyl]ferrocene (1), reacts readily with hydrogen peroxide and elemental sulfur to give the corresponding phosphane-oxide and phosphane-sulfide, respectively, and with platinum(II) and palladium(II) precursors to afford various bis(phosphane) complexes [MCl2(1 -,P)2] (M = trans -Pd, trans -Pt and cis -Pt). The anticancer activity of the compounds was evaluated in vitro with the complexes showing moderate cytotoxicities towards human ovarian cancer cells. Moreover, the biological activity was found to be strongly influenced by the stereochemistry, with trans -[PtCl2(1 -,P)2] being an order of magnitude more active than the corresponding cis isomer. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Synthesis and characterizations of N,N,-bis(diphenylphosphino)-2-(aminomethyl)aniline derivatives: application of a palladium(II) complex as pre-catalyst in Heck and Suzuki cross-coupling reactions

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2009
Murat Aydemir
Abstract The reaction of 2-(aminomethyl)aniline with 2 equivalents of PPh2Cl in the presence of Et3N, proceeds in CH2Cl2 to give N,N,-bis(diphenylphosphino)-2-(aminomethyl)aniline 1 in good yield. Oxidation of 1 with aqueous H2O2, elemental sulfur or gray selenium gave the corresponding oxide, sulfide and selenide dichalcogenides [Ph2P(E)NHC6H4CH2NHP(E)Ph2] (E: O, 2a; S, 2b; Se, 2c), respectively. The reaction of [Ph2PNHC6H4CH2NHPPh2] with PdCl2(cod), PtCl2(cod) and [Cu(MeCN)4]PF6 gave the corresponding chelate complexes, PdCl21, PtCl21 and [Cu(1)2]PF6. The new compounds were fully characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of the Pd(II) complex was tested in the Suzuki coupling and Heck reactions. The Pd(II) complex catalyzes the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes respectively, in good yields. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Development of a novel process for the biological conversion of H2S and methanethiol to elemental sulfur

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003
Jan Sipma
Abstract The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges, tested for their ability to degrade MT, revealed the presence of organisms capable of metabolizing MT as their sole source of energy. Furthermore, batch tests were executed to gain a better understanding of the inhibition potential of MT. It was found that increasing MT concentrations affected acetotrophic organisms more dramatically than methylotrophic organisms. Continuous reactor experiments, using two lab-scale upflow anaerobic sludge bed (UASB) reactors (R1 and R2), aimed to determine the maximal MT load and the effect of elevated sulfide concentrations on MT conversion. Both reactors were operated at a hydraulic retention time (HRT) of about 7 hours, a temperature of 30°C, and a pH of between 7.3 and 7.6. At the highest influent MT concentration applied, 14 mM in R1, corresponding to a volumetric loading rate of about 50 mM MT per day, 87% of the organic sulfur was recovered as hydrogen sulfide (12.2 mM) and the remainder as volatile organic sulfur compounds (VOSCs). Upon decreasing the HRT to 3.5 to 4.0 h at a constant MT loading rate, the sulfide concentration in the reactor decreased to 8 mM and MT conversion efficiency increased to values near 100%. MT conversion was apparently inhibited by the high sulfide concentrations in the reactor. The specific MT degradation rate, as determined after 120 days of operation in R1, was 2.83 ± 0.27 mmol MT g VSS,1 day,1. During biological desulfurization of liquid hydrocarbon phases, such as with liquefied petroleum gas (LPG), the combined removal of hydrogen sulfide and MT is desired. In R2, the simultaneous addition of sodium sulfide and MT was therefore studied and the effect of elevated sulfide concentrations was investigated. The addition of sodium sulfide resulted in enhanced disintegration of sludge granules, causing significant washout of biomass. Additional acetate, added to stimulate growth of methanogenic bacteria to promote granulation, was hardly converted at the termination of the experimental period. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 1,11, 2003. [source]

Biological Conversion of Anglesite (PbSO4) and Lead Waste from Spent Car Batteries to Galena (PbS)

BIOTECHNOLOGY PROGRESS, Issue 4 2002
Jan Weijma
Lead paste, a solid mixture containing PbSO4, PbO2, PbO/Pb(OH)2precipitate, and elemental Pb, is one of the main waste fractions from spent car batteries. Biological sulfidation represents a new process for recovery of lead from this waste. In this process the lead salts in lead paste are converted to galena (PbS) by sulfate-reducing bacteria. This paper investigates a continuous process for sulfidation of anglesite (PbSO4), the main constituent of lead paste, and lead paste, consisting of a laboratory-scale gas-lift bioreactor to which a slurry of anglesite or lead paste was supplied. Sulfate or elemental sulfur was added as an additional sulfur source. Hydrogen gas served as an electron donor for the biological reduction of sulfate and elemental sulfur to sulfide by sulfate- and sulfur-reducing bacteria. Anglesite was almost completely converted to galena at a loading rate of 19 kg of PbSO4m,3day,1, producing a sludge of which the crystalline lead phases consisted of >98% PbS (galena) and 1,2% elemental Pb. With lead paste, stable sulfidation rates of up to 17 kg of lead paste m,3day,1were demonstrated, producing a sludge of which the crystalline lead phases consisted of an estimated >96% PbS, 1,2% elemental Pb, and 1,2% PbO2. [source]

Reactivity of 1-Hydro-5-carbaphosphatrane Based on Tautomerization between Pentavalent Phosphorane and Trivalent Cyclic Phosphonite

CHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2006
Junji Kobayashi Dr.
Abstract The reaction behavior of 1-hydro-5-carbaphosphatrane (1,a) was examined. Treatment of 1,a with oxidants such as 3-chloroperoxybenzoic acid (mCPBA) and tBuOCl gave cyclic phosphonate 2 and 1-chloro-5-carbaphosphatrane (4), respectively, via cyclic phosphonite 3, a tautomer of 1,a. Compound 4 was readily hydrolyzed to afford 2. Compound 1,a was also sulfurized via 3 by elemental sulfur to afford cyclic thioxophosphonate 5, which was also obtained by reactions in the presence of bases. Treatment of 1,a with bases also proceeded through 3 to give an equilibrium mixture of the corresponding phenoxide anion 10 and the phosphoranide anion 9, which was quenched with MeI to afford a mixture of 11 and 1-methyl-5-carbaphosphatrane (1,b). Such reactivities are typical for neutral phosphoranes. Theoretical investigations of these reactivities were also performed. [source]