- Spectroscopic characterization of ethyl xanthate oxidation products and analysis by ion interaction chromatography
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An ion interaction chromatographic separation method, coupled with UV spectroscopic detection, has been developed for the analysis of ethyl xanthate (O-ethyl dithiocarbonate) and its oxidative decomposition products in mineral flotation systems. The effects of the ion-pairing agent (tetrabutylammonium ion), pH modifier (phosphoric acid), and organic modifier (acetonitrile) in the eluant upon the retention characteristics of the ethyl xanthate oxidation products have been determined. The optimized separation procedure has been successfully applied to the analysis of ethyl xanthate and its oxidation products in a nickel-iron sulfide mineral suspension containing a number of other anionic species, including cyanide complexes of nickel and iron, as well as sulfur-oxy anions. The ethyl xanthate oxidation products investigated in this study have been isolated as pure compounds and characterized by UV-visible, FT-IR, and NMR spectroscopies. The UV-visible and FT-IR spectroscopic properties of these species are discussed in terms of the chemical modifications of the thiocarbonate group.
- Hao, Fu Ping,Silvester, Ewen,Senior, Geoffrey David
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- Interactions between Sulphide Minerals and Alkylxanthate Ions Part 1.-A Vibrational Spectroscopic Study of the Interactions between Sphalerite and Synthetic Zinc(II) and Cadmium(II) Sulphides, and Ethylxanthate Ions in Aqueous and Acetone Solutions
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The crystal structures of zinc(II) and cadmium(II) sulphides are not affected by the stoichiometry of metal and sulphide ions at the precipitation of the two compounds.The composition and structure of the ultimate surface layers, and thereby the chemical properties of the particles, are on the other hand sensitive to the stoichiometry at the preparation.Chemisorbed ethylxanthate complexes are formed at metal ion sites on the surfaces of sphalerite and synthetic zinc(II) and cadmium(II) sulphides at metal and ethylxanthate ion concentrations where the solubility product of zinc(II) or cadmium(II) ethylxanthate is not exceeded.Two different types of ethylxanthate species co-ordinated to the surfaces have been found.These have been assigned to mono- and bi-dentate co-ordination of the ethylxanthate ion to the surface.Surface complexes are most probably enthalpy stabilized, and the bond(s) between the metal ion site in the surface and the ligand must contain some degree of covalency, as the entropy contribution to the formation of a chemisorbed complex on a surface is small.The stability of complexes of this kind is expected to increase with increasing softness of metal site and ligand.This is indicated as the ethylxanthate and EDTA surface complexes on cadmium(II) sulphide seem to be more stable than the corresponding complexes on zinc(II) sulphide surfaces.The stability of the surface complex is dependent on the solvent used, and seems to be a function of the solvation properties of the solvent.
- Persson, Per,Malmensten, Bo,Persson, Ingmar
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- VIBRATIONAL ANALYSIS OF ALKYL XANTHATES
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Rotational isomers are indicated in the Raman spectra of sodium ethyl and other xanthates.Vibrational bands useful for characterizing xanthate solids and aqueous solutions are given.Vibrational analyses are reported for sodium ethyl xanthate, trans and gauche forms, and the methyl and isopropyl analogs using a Cartesian coordinate force field derived from ab initio molecular orbital calculations.
- Colthup, N. B.,Powell, L. Porter
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- Synthesis of CO2-philic xanthate-oligo(vinyl acetate)-based hydrocarbon surfactants by RAFT polymerization and their applications on preparation of emulsion-templated materials
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Amphiphilic block copolymers poly(ethylene glycol)-block-oligo(vinyl acetate) (PEG-b- OVAc) and OVAc-b-PEG-b-OVAc have been demonstrated to be effective surfactants for CO2-in-water (C/W) emulsions. However, the high cost and difficulty of synthesis process can render the economics of CO2 process unfavorable. In this work, by reversible addition-fragmentation chain transfer (RAFT) polymerization, a series ofwell-defined CO2-philic triblock copolymers X-OVAc-b-PEG-b-OVAc- X(whereXstands for xanthate group) were synthesized. The structures and molecular weights of these copolymers were characterized by 1H NMRand GPC. The results of GPC analysis exhibited relatively narrow polydispersity (PDI1.35). The process of preparation of X-OVAc-based surfactants was much more simple, inexpensive and also easy to control, which could promote industrial-scale applications. The X-OVAc-based surfactants were found effectively to produce highly concentrated stable C/W emulsions. Porous emulsion-templated materials were prepared by the polymerization of the continuous phase of C/W emulsions. The open-cell morphology of the emulsion-templated materials was evidenced by scanning electron microscope. To tune the morphology of the porous structures, the influence of the surfactant concentration and molecular weight ofOVAcblock were also investigated. It was shown that X-OVAc-based surfactants can outperform perfluorinated surfactants and approach OVAc-based surfactants for such applications.
- Chen, Keping,Grant, Neil,Liang, Liyun,Zhang, Haifei,Tan, Bien
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- Syntheses, structures, and electrochemical studies of N,N′-bis(alkylthiocarbamate)butane-2,3-diimine Cu(II) complexes as pendent alkoxy derivatives of Cu(ATSM)
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A series of N2S2-Cu(II) complexes based on N,N′-bis(alkylthiocarbamate)butane-2,3-diimine ligands have been synthesized and characterized by spectroscopic, electrochemical, and single crystal X-ray diffraction methods. This class of ligands contains a conjugated N2S2chelate framework with a non-coordinating, terminal alkoxy (–OR) group. Ligands and Cu(II) complexes were investigated for R = Me, Et,nPr,iPr, and octyl. Additionally, N,N′-bis(ethylthiocarbamate)hexane-3,4-diimine and its Cu(II) complex were analyzed. Single crystal X-ray diffraction studies on all six Cu(II) complexes confirm a square planar Cu(II) environment with no significant changes in the core structure as a function of R. Spectroscopic studies are consistent with a similar electronic environment in all complexes. However, electrochemical investigations reveal significant shifts in the CuII/Iand CuIII/IIreduction potentials throughout the series. The complexes are analogues of the well-known bis(thiosemicarbazone) Cu(II) which contain a similar donor core with terminal, non-coordinating amines. Substitution of the terminal amines of bis(thiosemicarbazones) with the alkoxy groups of N,N′-bis(alkylthiocarbamate)butane-2,3-diimines allows tuning of redox potentials with minimal changes in the physical and electronic structure.
- Vishnosky, Nicholas S.,Mashuta, Mark S.,Buchanan, Robert M.,Grapperhaus, Craig A.
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- 1-Alkyl-4-ethoxythiocarbonyl-5-hydroxy-3-methylpyrazole: Synthesis, copper complexes and solvent extraction studies
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1-Alkyl-4-ethoxythiocarbonyl-5-hydroxy-3-methylpyrazole, HETCP, (alkyl = n-octyl ; n-dodecyl) were prepared in high yield by the reaction of 1-alkyl-3-methyl-2-pyrazolin-5-one with bis (ethoxythiocarbonyl)sulfide and sodium acetate in dimethylformamide. These reagents act as O, S bidentate ligands in solvent extraction/reextraction studies of Cu (II) from acid aqueous solutions and the extracted specie resulted to be Cu(ETCP)2.
- Oliva, Alfonso,Molinari, Aurora,Toro, Carolina
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- Polyvinyl alcohol as a biocompatible alternative for the passivation of gold nanorods
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The functionalization of gold nanorods (GNRs) with polymers is essential for both their colloidal stability and biocompatibility. However, a bilayer of the toxic cationic surfactant cetyl trimethylammonium bromide (CTAB) adsorbed on the nanorods complicates this process. Herein, we report on a strategy for the biocompatible functionalization of GNRs with a hydrophobic polymeric precursor, polyvinyl acetate, which is then transformed into its hydrophilic analogue, polyvinyl alcohol. This polymer was chosen due to its well-established biocompatibility, tunable "stealth" properties, tunable hydrophobicity, and high degree of functionality. The biocompatibility of the functionalized GNRs was tested by exposing them to primary human blood monocyte derived macrophages; the advantages of tunable hydrophobicity were demonstrated with the long-term stable encapsulation of a model hydrophobic drug molecule.
- Kinnear, Calum,Burn, David,Clift, Martin J. D.,Kilbinger, Andreas F. M.,Rothen-Rutishauser, Barbara,Petri-Fink, Alke
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- One-pot synthesis and methylation of 3-[2-(1 H -benzimidazol-2-yl-sulfanyl) -acetyl]-chromen-2-ones
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3-(2-Bromoacetyl)coumarins (I), when treated with 2-mercatobenzimidazole (II) in acetone containing K2CO3 (mild base) and tetrabutylammonium bromide (TBAB) as a phase transfer catalyst, at room temperature yielded the title compound 3-[2-(1H-benzimidazole-2-yl-sufanyl)- acetyl]-chromen-2-one (III) in a one-pot synthesis. Alternatively, III could also be prepared by treating dithiocarbonic acid O-ethyl ester, S-[2-oxo-2-(2-oxo-2H-chromen3-yl)-ethyl] ester (V), with o-phenylenediamine (VI). The methylation of the title compound III was performed with dimethyl sulfate (DMS), in acetonitrile containing TBAB and K2CO3 at room temperature, resulting in 3-[2-(N-methyl-benzimidazol-2-yl-sulfanyl)]- acetyl-chromen-2-ones (VII). Alternatively, methylation of III could also be performed with DMS in acetonitrile containing K2CO3 as base and clay as surface catalyst. All the compounds were synthesized in good yields and their structures were confirmed by spectral and analytical data. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: 1H NMR of IIIB, VB and VIIB] Copyright Taylor and Francis Group, LLC.
- Tasqeeruddin,Dubey
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- Visible-Light-Driven MADIX Polymerisation via a Reusable, Low-Cost, and Non-Toxic Bismuth Oxide Photocatalyst
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The continuous amalgamation of photocatalysis into existing reversible deactivation radical polymerisation (RDRP) processes has initiated a rapidly propagating area of polymer research in recent years. We introduce bismuth oxide (Bi2O3) as a heterogeneous photocatalyst for polymerisations, operating at room temperature with visible light. We demonstrate formidable control over degenerative chain-transfer polymerisations, such as macromolecular design by interchange of xanthate (MADIX) and reversible addition-fragmentation chain-transfer (RAFT) polymerisation. We achieved narrow molecular weight distributions and attribute the excellent temporal control of a photo-induced electron transfer (PET) process. This methodology was employed to synthesise diblock copolymers combining differently activated monomers. The Bi2O3 catalyst system has the additional benefits of low toxicity, reusability, low-cost, and ease of removal from the reaction mixture.
- Hakobyan, Karen,Gegenhuber, Thomas,McErlean, Christopher S. P.,Müllner, Markus
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- Amphiphilic poly(N-vinyl pyrrolidone) grafted graphene by reversible addition and fragmentation polymerization and the reinforcement of poly(vinyl acetate) films
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The reversible addition and fragmentation (RAFT) polymerization of vinyl pyrrolidone (VP) from graphene oxide (GO) is used to produce GO-g-PVP (GP) and the grafting is confirmed from Fourier transformed infrared (FTIR) and nuclear magnetic resonance spectra. The average thickness of GP (8.2 nm) obtained from atomic force microscopy is higher than that of GO (1.2 nm), indicating the wrapping of grafted PVP on the GO sheets. Transmission electron microscopy of GP exhibits swollen domains (white spots) characterizing the grafted PVP chains from the GO surface. The dispersibility of the GP sheets becomes greatly improved over that of GO and they are dispersible in the solvents of Hansen solubility parameter (δp + δH) range 6.3-58. Three nanocomposites GP1, GP3 and GP5, produced by mixing with 1, 3 and 5 (w/w)% GP with poly(vinyl acetate) (PVAc), produce a stable dispersion in dimethyl formamide, although mixtures of GO and PVAc do not. The field emission scanning electron microscopy of the GP5 sample indicates a good homogeneous dispersion of GP sheets within the PVAc matrix, although both GO and PVP are individually immiscible with PVAc. The FTIR data indicates a specific interaction between GP and PVAc. The glass transition temperature (Tg) of the pure PVAc increases in the GP composites, but in the GO composite it remains unchanged. In the GPP5 hybrid containing the GO, PVP and PVAc mixture produced at the same composition as in GP5, an increase of Tg is seen to a lesser degree than that of GP, indicating that GO acts as a compatibilizer of a PVP and PVAc immiscible blend. The mechanical properties of PVAc exhibit a strong reinforcement and the Young's modulus & tensile strength data show a 190% and 169% increase over PVAc in the GP5 sample due to the homogenous dispersion and unidirectional (parallel) orientation of GP sheets in the composite film.
- Layek, Rama K.,Kuila, Atanu,Chatterjee, Dhruba P.,Nandi, Arun K.
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- Synthesis of oligomer vinyl acetate with different topologies by RAFT/MADIX method and their phase behaviour in supercritical carbon dioxide
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Poly(vinyl acetate) (PVAc) has been shown to exhibit anomalously high solubility in CO2 as compared to other vinyl hydrocarbon polymers. Understanding the phase behaviour of PVAc with different topologies in CO 2 is very important for its potential applications as suitable surfactant, or phase transfer agent in a CO2 solvent process. In this study, a series of PVAcs with different topologies (bi-arms, tri-arms, tetra-arms) were synthesized by RAFT/MADIX method. The structures and molecular weights of these polymers were characterized by 1H NMR and GPC. The phase behaviours of PVAcs in dense carbon dioxide fluid were determined, and the results show that the PVAc with more arms has lower cloud point pressure.
- Zhang, Shoucun,Chen, Keping,Liang, Liyun,Tan, Bien
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- A molecular precursor route to quaternary chalcogenide CFTS (Cu2FeSnS4) powders as potential solar absorber materials
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In the present work we report on the synthesis of tetragonal stannite Cu2FeSnS4 powders using a solvent free melt method using a mixture of Cu, Fe, and Sn(ii)/Sn(iv) O-ethylxanthates heated at different temperatures. The as-synthesized powders were characterized by powder X-ray diffraction (p-XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis absorption spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, which confirm the successful synthesis of stannite CFTS. Optical measurements show that Cu2FeSnS4 powders have visible light absorption onsets in the far red with direct band gap energies in the range 1.32-1.39 eV which are suitable for acting as efficient absorber layers in solar cells. Electronic characterisation of these materials deposited as thin films by spin coating show that they are p type semiconductors with respectable carrier mobilities of ca. 60 cm2 V-1 s-1 with carrier densities on the order of 1014 cm-1.
- Alanazi, Abdulaziz M.,Alam, Firoz,Salhi, Abdelmajid,Missous, Mohamed,Thomas, Andrew G.,O'Brien, Paul,Lewis, David J.
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- Effect of ligands on crystallography, morphology and photo-catalytic ability of ZnS nanostructures
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ZnS nanostructures have been synthesized using zinc complexes: Zn(ethyl xanthate)2] & [Zn(morpholine4-dithiocarbamate)2] from ligands potassium ethyl xanthate (KEX) and morpholine4-dithiocarbamate (MDTC) by solvothermal route of synthesis. Crystallographic and morphological analyses of synthesized ZnS nanostructures have been done by X-ray diffraction (XRD) and electron microscopy [Transmission Electron Microscope (TEM)], respectively. Diffraction and electron microscope studies reveal the formation of hexagonal structured ZnS nanocrystals of various morphologies (nanosheets & nanorods). UV–vis. absorption studies have been carried for the detailed optical analyses. Photoluminescence (PL) study was carried out to check luminescence of synthesized ZnS nanostructures in blue region of electromagnetic spectrum. It has been reported that the morphology of synthesized nanostructures strongly depends upon the precursor complexes prepared from two different classes of ligands; potassium ethyl xanthate and morpholine4-dithiocarbamate. Photo-catalytic activity potential of the synthesized ZnS nanostructures has been tested in UV light using methylene blue (MB) dye as a test contaminant in aqueous media. About 88.49% and 87.96% of MB dye was photo-degraded by ZnS nanostructures synthesized from Zn(EX)2 [ where EX stands for ethyl xanthate] and Zn(MDTC)2, respectively.
- Kaur, Balwinder,Singh, Karamjit,Malik, Ashok Kumar
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- Ubiquitous Nature of Rate Retardation in Reversible Addition-Fragmentation Chain Transfer Polymerization
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Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most powerful reversible deactivation radical polymerization (RDRP) processes. Rate retardation is prevalent in RAFT and occurs when polymerization rates deviate from ideal conventional radical polymerization kinetics. Herein, we explore beyond what was initially thought to be the culprit of rate retardation: dithiobenzoate chain transfer agents (CTA) with more active monomers (MAMs). Remarkably, polymerizations showed that rate retardation occurs in systems encompassing the use of trithiocarbonates and xanthates CTAs with varying monomeric activities. Both the simple slow fragmentation and intermediate radical termination models show that retardation of all these systems can be described by using a single relationship for a variety of monomer reactivity and CTAs, suggesting rate retardation is a universal phenomenon of varying severity, independent of CTA composition and monomeric activity level.
- Bradford, Kate G. E.,Petit, Leilah M.,Whitfield, Richard,Anastasaki, Athina,Barner-Kowollik, Christopher,Konkolewicz, Dominik
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supporting information
p. 17769 - 17777
(2021/11/10)
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- Synthesis, structure and reactivity of some chiral benzylthio alcohols, 1,3-oxathiolanes and their S-oxides
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A series of amino acid-derived chiral benzylthio alcohols have been prepared and characterized. A chiral mercapto alcohol derived from S-leucine has been used to form three chiral 2,4-disubstituted 1,3-oxathiolanes. One of these has been oxidized to the S-oxide and another to the S,S-dioxide. The cis and trans isomers have been characterized by 1H NMR in each case and it appears that thermal epimerisation at C-2 is possible at the sulfoxide oxidation state. The X-ray structure of major trans diastereomer of 2-phenyl-4-isobutyl-1,3-oxathiolane S,S-dioxide shows an envelope conformation with oxygen at the flap and an internal angle at sulfur of just 93.8°. This compound fragments upon flash vacuum pyrolysis at 700°C to give SO2, benzaldehyde and 4-methylpent-1-ene.
- Aitken, R. Alan,Lightfoot, Philip,Thomas, Andrew W.
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p. 369 - 387
(2020/05/25)
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- Visible-Light-Induced Radical Carbo-Cyclization/ gem-Diborylation through Triplet Energy Transfer between a Gold Catalyst and Aryl Iodides
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Geminal diboronates have attracted significant attention because of their unique structures and reactivity. However, benzofuran-, indole-, and benzothiophene-based benzylic gem-diboronates, building blocks for biologically relevant compounds, are unknown. A promising protocol using visible light and aryl iodides for constructing valuable building blocks, including benzofuran-, indole-, and benzothiophene-based benzylic gem-diboronates, via radical carbo-cyclization/gem-diborylation of alkynes with a high functional group tolerance is presented. The utility of these gem-diboronates has been demonstrated by a 10 g scale conversion, by versatile transformations, by including the synthesis of approved drug scaffolds and two approved drugs, and even by polymer synthesis. The mechanistic investigation indicates that the merging of the dinuclear gold catalyst (photoexcitation by 315-400 nm UVA light) with Na2CO3 is directly responsible for photosensitization of aryl iodides (photoexcitation by 254 nm UV light) with blue LED light (410-490 nm, λmax = 465 nm) through an energy transfer (EnT) process, followed by homolytic cleavage of the C-I bond in the aryl iodide substrates.
- Hashmi, A. Stephen K.,Rominger, Frank,Si, Xiaojia,Zhang, Lumin
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supporting information
p. 10485 - 10493
(2020/07/03)
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- Production method of high-grade potassium xanthate
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The invention discloses a production method of high-grade potassium xanthate. The specific process of the method is as follows: mixing alcohol and flaky alkali, crushing and stirring to obtain a mixedsolution; transferring the mixed solution into a reaction kettle, slowly dropwise adding carbon disulfide, controlling the temperature of the system in the reaction kettle to be 30-35 DEG C in the dropwise adding process, continuously carrying out heat preservation reaction at 30-35 DEG C, and sequentially removing alcohol and drying the reacted system to obtain potassium xanthate. The preparation method comprises the following steps: adding flaky alkali into alcohol and carrying out wet crushing; so that the reaction is promoted, side reactions are reduced, and the conversion rate of materials is increased the grade of the potassium xanthate is increased to 95% or above, the problem that the grade of the potassium xanthate synthesized in the prior art is low is solved, an alkali grindingprocess is avoided, safe production is realized, and the environmental protection and safety pressure is reduced.
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Paragraph 0022-0084
(2020/09/12)
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- Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: Applications and mechanism thereof
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We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst. This journal is
- Balletti, Matteo,De Pedro Beato, Eduardo,Mazzarella, Daniele,Melchiorre, Paolo
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p. 6312 - 6324
(2020/08/24)
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- Water-soluble three qinqin amines benzene sulfonic acid alkali metal salt derivative and its preparation method and application
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The invention discloses a water soluble triazine amino benzene sulfonic acid alkali metal salt derivative and a preparation method and application thereof. The invention relates to a synthesis process and application of an amino benzene sulfonic acid sodium and xanthonic acid group-containing triazine derivative, and is characterized in that: the 2-alkyl xanthate-4, 6-diamino benzene sulfonic acid alkali metal salt-1,3,5-s-triazine has the following structural formula shown in the specification, wherein X is Na, R is C1-C4 straight chain or branched chain alkyl. The preparation method is as follows: using cyanuric chloride, amino benzene sulfonic acid and potassium alkyl xanthate with the molar ratio of 1: 1.1: 2-2.1 as raw materials for reaction in an organic solvent. The amino benzene sulfonic acid sodium-containing triazine derivative can be used as additives used in pure water, water-glycol, synthetic ester, lithium base grease or calcium base grease, and by compounding with other water-based lubricant additives, the water soluble triazine amino benzene sulfonic acid alkali metal salt derivative has good abrasion resistance, extreme pressure resistance, corrosion resistance, and oxidation resistance. The synthesis process has the advantages of simple operation, high yield, and easy control of reaction condition.
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Paragraph 0024; 0026
(2019/03/02)
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- Water-soluble triazine xanthogen derivative and its preparation method and application
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The invention discloses a water-soluble triazine xanthic acid derivative, and a preparation method and application thereof. The invention relates to a synthetic technology and application of a water-soluble triazine derivative containing a xanthic acid group. The derivative is characterized in that the derivative has the chemical name of 2,4-bis(N,N-dihydroxyalkylamino)-6-(alkylxanthate)-1,3,5-sym-triazine, and has the structural formula shown in the specification, and in the structural formula, R1 is a C1-C2 linear or branched alkyl, and R is a C1-C5 linear or branched alkyl. The preparation method of the derivative comprises utilizing cyanuric chloride, a dialkyl alcohol amine and an alkyl xanthate as raw materials, controlling the reaction molar ratio to be 1:2:1.1, taking an alcohol as a solvent, and reacting at 60-90 DEG C for 4-6 h. The derivative can be applied to pure water, water-glycol, water-glycerin, synthetic esters, polyesters and lubricating grease as an additive, also can be combined with other aqueous lubricating additives for usage, and has good wear resistance and extreme pressure resistance, and capabilities of resisting corrosion and resisting oxidation. The method is simple in operation, high in yield and easily controllable in reaction conditions.
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Paragraph 0023
(2019/03/29)
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- INHIBITORS OF SHORT-CHAIN DEHYDROGENASE ACTIVITY FOR PROMOTING NEUROGENESIS AND INHIBITING NERVE CELL DEATH
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A method of promoting neuroprotection in a subject from axonal degeneration, neuronal cell death, and/or glia cell damage after injury, augmenting neuronal signaling underlying learning and memory, stimulating neuronal regeneration after injury, and/or treating a disease, disorder, and/or condition of the nervous system in a subject in need thereof includes administering to the subject a therapeutically effective amount of a 15-PGDH inhibitor.
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Paragraph 00248
(2018/02/27)
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- Copper-catalyzed synthesis of thiazol-2-yl ethers from oxime acetates and xanthates under redox-neutral conditions
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A novel copper-catalyzed annulation of oxime acetates and xanthates for the synthesis of thiazol-2-yl ethers with remarkable regioselectivity has been developed. Various oxime acetates, whether derived from aryl ketones or alkyl ketones, or natural product cores are suitable for this conversion. Unique dihydrothiazoles were also obtained when both reaction sites were methine. Mechanistic studies indicated that imino copper(iii) intermediates were involved. In addition, this protocol proceeded under redox-neutral conditions and did not require additives or ligands.
- Zhu, Zhongzhi,Tang, Xiaodong,Cen, Jinghe,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 3767 - 3770
(2018/04/17)
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- Synthesis of novel substituted 3-(4-((1H-benzo[d]imidazol-2-ylthio)methyl)-1-phenyl-1H-pyrazol-3-yl)-2H-chromen-2-ones: various approaches
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Abstract: Considering benzimidazole as a privileged structure for developing probes of impressive pharmacological potentials, some new coumarin and pyrazole conjugates of benzimidazoles were synthesized with a sulphur linkage. Thus, 3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde (3) was prepared starting from simple salicylaldehyde which has been?used as an important synthon and incorporated in a series of structural manipulations to obtain various of pharmacophoric motif conjugates 9(a–b) and 13(a–f), in fair yields. We have developed facile and stepwise methods for the synthesis of all these compounds in various approaches, which also involves sub-sequences. All synthesized compounds were well characterized by IR, 1HNMR, 13CNMR and mass spectra data.
- Srikrishna, Devulapally,Dubey, Pramod Kumar
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p. 4455 - 4468
(2018/03/29)
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- Gemini surfactant synthesis method (by machine translation)
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The invention discloses Gemini surfactant synthesis method, comprises the following steps: (1) bromo methyl or bromo methyl synthesis; (2) synthesis of potassium xanthate; (3) synthesis of intermediate I; (4) synthesis of intermediate II. Prepared by the method of this invention of the Gemini surfactant, the critical micelle concentration and surface tension are relatively small, there is very good application prospect. (by machine translation)
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Paragraph 0024; 0025; 0026
(2017/08/28)
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- Precursor dependent morphological and photo-catalytic behaviour of CdS nanostructures
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Cadmium complexes based on Xanthate and dithiocarbamate such as [Cd(ethyl xanthate)2], [Cd(morpholine-4-dithiocarbamate)2] and [Cd(piperazine1-dithiocarbamate)2] have been used as efficient single source precursors. The formation of CdS nanostructures have been achieved by solvothermal route of synthesis. Crystallographic and morphological characterization of synthesized nanomaterials has been done by X-ray diffraction (XRD) and electron microscopy [Transmission Electron Microscope (TEM)], respectively. Diffraction and electron microscope studies reveal the formation of wurtzite structured CdS nanostructures of various morphologies (nanorods and nanospheres). UV–vis absorption and Fourier transform infrared (FTIR) spectroscopic studies have been carried for the detailed optical as well as qualitative analyses. It has been reported that the morphology of synthesized nanomaterials strongly depends upon the type of the precursor complexes. Photo-catalytic activity of the synthesized nanostructures has been tested in visible irradiation using methylene blue (MB) dye as a test contaminant in aqueous media. Morphology dependent photo-catalytic activity of the synthesized nanomaterials has been studied in detail to explore the potential of prepared nanostructures to purify polluted water.
- Kaur, Balwinder,Singh, Karamjit,Malik, Ashok Kumar
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p. 352 - 359
(2016/11/25)
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- INHIBITORS OF SHORT-CHAIN DEHYDROGENASE ACTIVITY FOR TREATING FIBROSIS
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A method of treating or preventing a fibrotic disease, disorder or condition includes administering to a subject in need of treatment a 15-PGDH inhibitor.
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Paragraph 00259
(2016/09/26)
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- Benzo [1,2-d:5,4-d '] b (oxazole) - 2,6-di-thiol and its preparation method
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The invention discloses benzo [1, 2-d: 5, 4-d']-di-(oxazole)-2, 6-dithiol and a preparation method thereof. The preparation method comprises the steps as follows: resorcinol is taken as a raw material, zinc chloride is taken as a catalyst, resorcinol and zinc chloride react with acetic oxide to obtain 4, 6-diacetylresorcinol; 4, 6-diacetylresorcinol reacts with hydroxylamine hydrochloride in sodium hydroxide to obtain 4, 6-di-[(1Z)-N-hydroxyethyliminumacyl]benzene-1, 3-diphenol; 4, 6-di-[(1Z)-N-hydroxyethyliminumacyl]benzene-1, 3-diphenol is taken as a raw material and subjected to Beckmann rearrangement reaction in a polyphosphoric acid system to obtain DAR*HCl; and DAR*HCl is taken as a raw material and reacts with carbon disulfide in a potassium hydroxide solution to obtain a target compound. According to the invention, sulfydryl is introduced at 2 and 6 sites simultaneously, the product is prepared through multiple steps of reaction, the method is simple, convenient and easy to operate, the melting point of the product is higher than 300 DEG C, and the yield is high.
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Paragraph 0013; 0027-0029
(2018/09/02)
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- Reversible addition-fragmentation chain transfer polymerization of vinyl acetate under high pressure
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In this work, high molecular weight polyvinyl acetate (PVAc) (Mn,GPC = 123,000 g/mol, Mw/Mn = 1.28) was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) under high pressure (5 kbar), using benzoyl peroxide and N,N-dimethylaniline as initiator mediated by (S)-2-(ethyl propionate)-(O-ethyl xanthate) (X1) at 35 C. Polymerization kinetic study with RAFT agent showed pseudo-first order kinetics. Additionally, the polymerization rate of VAc under high pressure increased greatly than that under atmospheric pressure. The "living" feature of the resultant PVAc was confirmed by 1H NMR spectroscopy and chain extension experiments. Well-defined PVAc with high molecular weight and narrow molecular weight distribution can be obtained relatively fast by using RAFT polymerization at 5 kbar.
- Chen, Jing,Zhao, Xiaoning,Zhang, Lifen,Cheng, Zhenping,Zhu, Xiulin
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p. 1430 - 1436
(2015/05/05)
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- Synthesis and antitumor activity of tetrahydrocarbazole hybridized with dithioate derivatives
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The present study reported the synthesis of tetrahydrocarbazoles hybridized with dithioate derivatives. Three series were synthesized namely alkyl dithiocarbonates (4a-d), heterocyclic dithiocarbamates (6a-g) and dialkyl dithiocarbamate (7). The synthesized compounds were tested in vitro on human breast adenocarcinoma cell line (MCF7) and the human colon tumor cell line (HCT116). Most of the synthesized compounds exploited potent antitumor activity, especially compound 6f [4-chlorophenylpiperazine derivative], which showed cytotoxic activity against MCF7 superior to doxorubicin with IC50 value of 7.24 nM/mL.
- El-Nassan, Hala Bakr
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p. 308 - 315
(2015/04/14)
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- COMPOSITIONS AND METHODS OF MODULATING SHORT-CHAIN DEHYDROGENASE ACTIVITY
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Compounds and methods of modulating 15-PGDH activity, modulating tissue prostaglandin levels, treating disease, diseases disorders, or conditions in which it is desired to modulate 15-PGDH activity and/or prostaglandin levels include 15-PGDH inhibitors described herein.
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Paragraph 00453
(2015/05/19)
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- Xanthates and trithiocarbonates strongly inhibit carbonic anhydrases and show antiglaucoma effects in vivo
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Dithiocarbamates (DTCs) were recently discovered as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. A series of xanthates and a trithiocarbonate, structurally related to the DTCs, were prepared by reaction of alcohols/thiols with carbon disulfide in the presence of bases. These compounds were tested for the inhibition of four human (h) isoforms, hCA I, II, IX, and XII, involved in pathologies such as glaucoma (CA II and XII) or cancer (CA IX). Several low nanomolar xanthate/trithiocarbonate inhibitors targeting these CAs were detected. A docking study of some xanthates within the CA II active site showed that these compounds bind in a similar manner with the dithiocarbamates, coordinating monodentately to the Zn(II) ion from the enzyme active site. Several xanthates showed potent intraocular pressure lowering activity in two animal models of glaucoma via the topical administration. Xanthates and thioxanthates represent two novel, promising classes of CA inhibitors.
- Carta, Fabrizio,Akdemir, Atilla,Scozzafava, Andrea,Masini, Emanuela,Supuran, Claudiu T.
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p. 4691 - 4700
(2013/07/19)
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- A general and facile one-pot process of isothiocyanates from amines under aqueous conditions
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A general and facile one-pot protocol for the preparation of a broad range of alkyl and aryl isothiocyanates has been developed from their corresponding primary amines under aqueous conditions. This synthetic process involves an in situ generation of a dithiocarbamate salt from the amine substrate by reacting with CS2 followed by elimination to form the isothiocyanate product with cyanuric acid as the desulfurylation reagent. The choice of solvent is of decisive importance for the successful formation of the dithiocarbamate salt particularly for highly electron-deficient substrates. This novel and economical method is suitable for scale-up activities.
- Sun, Nan,Li, Bin,Shao, Jianping,Mo, Weimin,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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body text
p. 61 - 70
(2012/04/04)
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- S1P RECEPTORS MODULATORS AND THEIR USE THEREOF
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The invention relates to novel compounds that have S1P receptor modulating activity. Further, the invention relates to a pharmaceutical comprising at least one compound of the invention for the treatment of diseases and/or conditions caused by or associated with inappropriate S1P receptor modulating activity or expression, for example, autoimmune response. A further aspect of the invention relates to the use of a pharmaceutical comprising at least one compound of the invention for the manufacture of a medicament for the treatment of diseases and/or conditions caused by or associated with inappropriate S1P receptor modulating activity or expression such as autoimmune response.
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Page/Page column 105
(2010/04/30)
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- Synthesis and anticancer evaluation of α-lipoic acid derivatives
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α-Lipoic acid derivatives were synthesized and evaluated for their in vitro anticancer activities against NCI-460, HO-8910, KB, BEL-7402, and PC-3 cell lines. The results, for most compounds exhibited dose-dependent inhibitory property and several compounds had good inhibitions at the dose of 100 μg/mL. Compound 17m was further selected for in vivo evaluation against S180 xenograft in ICR mice, which had 24.7% tumor-weight inhibition through intragastric administration of 200 mg/kg of body weight. Moreover, the LD50 in mice for 17m through ig exceeded 1000 mg/kg of body weight.
- Zhang, Shi-Jie,Ge, Qiu-Fu,Guo, Dian-Wu,Hu, Wei-Xiao,Liu, Hua-Zhang
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scheme or table
p. 3078 - 3083
(2010/07/18)
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- Palladium-catalyzed domino ring-opening/carboxamidation reactions of N -tosyl aziridines and 2-iodothiophenols: A facile and efficient approach to 1,4-benzothiazepin-5-ones
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A novel and efficient domino procedure has been developed for the synthesis of 1,4-benzothiazepin-5-ones from simple and readily accessible N-tosyl aziridines and o-iodothiophenols. This process involves aziridines ring-opening with o-iodothiophenols, followed by palladium-catalyzed intramolecular carboxamidation. The scope and limitation of this transformation have been investigated in detail by using various aziridines and o-iodothiophenols.
- Zeng, Fanlong,Alper, Howard
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supporting information; experimental part
p. 5567 - 5569
(2011/02/23)
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- The mechanisms of hydrolysis of alkyl N-alkylthioncarbamate esters at 100°C
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The hydrolysis of ethyl N-ethylthioncarbamate (ETE) at 100°C was studied in the range of 7 mol/L HCl to 4 mol/L NaOH. The pH-rate profile showed that the hydrolysis occurred through specific acid catalysis at pH 6.5. The Hammett acidity plot and the excess acidity plot against X were linear. The Bunnett-Olsen plot gave a negative slope indicating that the conjugate acid was less hydrated than the neutral substrate. It was concluded that the acid hydrolysis occurred by an Al mechanism. The neutral species hydrolyzed with general base catalysis shown by the Bronsted plot with β = 0.48 ± 0.04. Water acted as a general base catalyst with (pseudo-)first-order rate constant, kN = 3.06 × 10-7 s-1. At pH > 6.5 the rate constants increased, reaching a plateau at high basicity. The basic hydrolysis rate constant of ethyl N,N-diethylthioncarbamate, which must react by a BAc2 mechanism, increased linearly at 1-3 mol/L NaOH with a second-order rate constant, k2 = 2.3 × 10-4 (mol/L)-1 s-1, which was 10 times slower than that expected for ETE. Experiments of ETE in 0.6 mol/L NaOH with an excess of ethylamine led to the formation of diethyl thiourea, presenting strong evidence that the basic hydrolysis occurred by the E1cb mechanism. In the rate-determining step, the E1cb mechanism involved the elimination of ethoxide ion from the thioncarbamate anion, producing an isothiocyanate intermediate that decomposed rapidly to form ethylamine, ethanol, and COS.
- Humeres, Eduardo,Sanchez, Maria De Nazare,Lobato, Conceicao M. L.,Debacher, Nito A.,De Souza, Eduardo P.
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p. 1483 - 1491
(2007/10/03)
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- PYRANOBENZOTHIOPHENE DERIVATIVES TO TREAT INFECTION WITH HEPATITIS C VIRUS
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The invention is directed to a compound of the formula: (I) wherein substitutions at R1, R2 , R3 - R12,and Y are set forth in the specification; pharmaceutical compositions comprising said compound, methods of treating or preventing a Hepatitis C viral infection in a mammal comprising contacting the mammal with an effective amount of said compound or pharmaceutical compositions including said compound and methods of inhibiting replication of a Hepatitis C virus comprising contacting the HCV virus with an effective amount of said compound or pharmaceutical compositions including said compound.
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Page/Page column 33
(2008/06/13)
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- Mechanism of the alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio-and dithiocarbonates
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The alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio-and dithiocarbonates, 1 and 2, respectively, were studied kinetically in 5% dioxane in water, at 25.0°C, and ionic strength 0.2 mol dm-3 (KCl). Two kinetic processes, well separated in time, were detected. The fast process involves the formation of a σ-complex by addition of HO- to one of the unsubstituted positions of the aromatic ring, followed by fast ionisation of this complex. The slow process leads to the formation of a mixture of 2,4,6-trinitrophenoxide and 2,4,6-trinitrobenzenethiolate ions in a 10:1 ratio, respectively, in the reaction of 2, and to a mixture in a 2:1 ratio in the reaction of 1, independent of KOH concentration. Although the substrates show different kinetic behaviour with KOH concentration, the results can be discussed on the basis of a common reaction mechanism.
- Castro, Enrique A.,Cubillos, Maria,Santos, Jose G.,Bujan, Elba I.,Remedi, M. Virginia,Fernandez, Mariana A.,De Rossi, Rita H.
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p. 2603 - 2607
(2007/10/03)
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- Hydrolysis and aminolysis of alkyl xanthate esters and cellulose analogues
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The hydrolysis and aminolysis of a series of S-substituted O-alkylxanthate esters was studied in 20% v/v aqueous methanol at 35°C. The pH-rate profiles of the hydrolyses showed water and hydroxide-ion-catalyzed reactions. The reaction of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) and p-nitrobenzyl cellulose xanthate (CelXNB) with polyalanine and lysozyme produced a covalent bond between the polypeptide and the cellulose matrix, as shown by solid-state 13C NMR. However, the nature of the bonding could not be identified. The reaction of nucleophiles (H2O, OH-, RNH2) and xanthic esters was consistent with an addition-elimination mechanism through a tetrahedral intermediate. Bronsted plots against the pKa of the nucleophile (βnu) or the nucleofuge of the substrate (βlg) were used to characterize the rate-determining step. The pKa values of the nucleophiles ranged between -1.74 and 15.74, and for the nucleofuges, they were in the range of 10.50-0.92. For nucleophiles with pKa values up to about 10, βlg was 0.10-0.15, and βnu changed from 0.48 to 0.35 for the strongest electron-withdrawing nucleofuge. It was concluded that the water-catalyzed hydrolyses, and also aminolyses with moderately basic amines, occur with rate-determining formation of the tetrahedral intermediate. For strong bases such as hydroxide ion, the disappearance of the intermediate becomes the slowest step. The reaction of cellulose xanthic esters with external nucleophiles as hydroxide ion and amines shows simple first-order kinetics and is slower than alkyl or sugar xanthates, probably due to the diffusion effect through the tight cybotactic region of cellulose.
- Humeres, Eduardo,Soldi, Valdir,Klug, Marilene,Nunes, Mauricea,Oliveira, Celia M.S.,Barrie, Patrick J.
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p. 1050 - 1056
(2007/10/03)
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- Polysubstituted benzimidazoles as antiviral agents
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Polysubstituted benzimidazoles and pharmaceutical compositions containing them as the active ingredients. These compounds and compositions exhibit antiviral activity against viruse of the herpes family, particularly human cytomegalovirus and herpes simplex viruses (HSV).
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- Polysubstituted benzimidazoles as antiviral agents
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This invention relates to novel polysubstituted benzimidazoles and compositions and their use in the treatment of viral infections. The polysubstituted benzimidazoles and compositions of the present invention exhibit antiviral properties against viruses of the herpes family, particularly human cytomegalovirus (HCMV) and herpes simplex viruses (HSV). Preferred polysubstituted benzimidazoles of the invention are 2,5,6-Trichloro-1-(β-D-5-deoxyribofuranosyl)benzimidazole and 2-bromo-5,6-dichloro-1-(5-deoxy-β-D-ribofuranosyl)benzimidazole.
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- Preparation of Benzothiophenes by Pd(0)-Catalyzed Intramolecular Cyclization of Allyl (and Propargyl) o-Iodophenyl Sulfides
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Benzothiophenes are prepared by intramolecular Pd(0)-catalyzed Heck reaction of allyl o-iodophenyl sulfides.Pd(0)-Catalyzed intramolecular cyclization of o-iodophenyl propargyl sulfide in the presence of a hydride donor gives 3-methylene-2,3-dihydrobenzothiophene, which reacts with several enophiles in ene type reactions.However, allyl (and propargyl) aryl sulfides react with palladium(II) chloride to afford polymeric 2.
- Arnau, Narcis,Moreno-Manas, Marcial,Pleixats, Roser
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p. 11019 - 11028
(2007/10/02)
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- Alkylxanthate, production thereof, photopolymerization initiator, and polymerization employing the same
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Alkylxanthate compound having the general formula: where R1 is an alkyl group of 1 to 18 carbons. The compound is useful as an initiator of photopolymerization of various radical-polymerizable monomers, and produced by reacting an aliphatic alcohol having the general formula:, , R2OH, , where R2 is an alkyl group of 1 to 18 carbons with carbon disulfide, alkali metal hydroxide or alkali metal, and p-xylylene dichloride. Photopolymerization initiator comprising the alkylxanthate. Process for producing a polymer having a xanthate end group at the both ends, comprising irradiating ultraviolet ray to a mixture of the alkylxanthate and a radical-polymerizable monomer and chloroprene polymer having the general formula: where R1 is an alkyl group of 1 to 18 carbons; M is a chloroprene radical; n denotes the polymerization degree, and having a number-average molecular weight of from 1,000 to 15,000.
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- Synthesis and Characterization of Bis(xanthate) Complexes of Mo(II) and W(II). Crystal Structure of
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The reactions of with potassium xanthates, K(S2COR), give the red crystalline compounds t (4) in which the xanthate groups seem to act as ν3-(S,S',C) pseudo-allylic ligands.Formation of the dicarbonyl species is not detected, but the isopropyl derivative (5) can be obtained by carbonylation of (3) under relatively forcing conditions.The tungsten complex reacts similary with K(S2COR) but gives mixtures of (n=1 or 2).The monophosphine derivatives exhibit n.m.r. spectroscopic features similar to those of (1)--(5), but for the bis(phosphine) species a formulation containing uni- and bi-dentaxe xanthate groups, is proposed, aand this has been confirmed by an X-ray crystal structure determination of complex (9). Formation of the dithiocarbonate complexes, during the reactions leading to the above xanthates has also been observed.Complex (9) istriclinic, space group P1, with unit-cell constants a=8.775(2), b=14.027(5), c=11.806(5) angstroem,α=106.09(2), β=75.74(3), γ=109.06(4)deg, and Z=2.The structure was refined to an R value of 0.032 by using 2878 independent observed refrections.
- Carmona, Ernesto,Contreras, Leopoldo,Sanches, Luis J.,Gutierrez-Puebla, Enrique,Monge, Angeles
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p. 2003 - 2010
(2007/10/02)
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- Synthesis of Novel 1,3-Dithiolan-2-one Derivatives
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Novel 1,3-dithiolan-2-one derivatives were prepared starting from α,β- or β,γ-dichlorinated carboxylic esters and potassium O-ethyl dithiocarbonate.The scope and the mechanism of this reaction were investigated.The biological uses of the compounds obtained here were examined.
- Yasuda, Naohiko,Yamatani, Tetsuo,Ohnuki, Takashi,Okutsu, Masaru
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p. 1845 - 1848
(2007/10/02)
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- A General Strategy for Elaboration of the Dithiocarbonyl Functionality, -(C=O)SS-: Application to the Synthesis of Bis(chlorocarbonyl)disulfane and Related Derivatives of Thiocarbonic Acids
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A variety of sulfenyl chlorides have been reacted with a variety of alkoxythiocarbonyl compounds to give adducts which then lose (spontaneously, or upon thermolysis, or in the presence of Lewis acid catalyst) the alkyl chloride to provide an assortment of dithiocarbonyl compounds in good to excellent yields.The preparations of bis(chlorocarbonyl)disulfane (1), ((trichloromethyl)dithio)carbonyl chloride (2), ((alkoxycarbonyl)dithio)carbonyl chlorides (3 and 4), and (((alkylthio)carbonyl)dithio)carbonyl chlorides (5 and 6) by this methodology were optimized; some of the (alkoxydichloromethyl)disulfanyl adducts, e.g., ROCCl2SS(C=O)Cl (10) and ROCCl2SS(C=O)OR'(54), were reasonable stable and could be isolated.All new compounds were characterized by analytical data, 1H and 13C NMR, IR, UV, and mass spectrometry, and high-yield derivatizations with alcohols or N-methylaniline.The reaction with N-methylaniline was also adapted to a rapid, convenient, and precise analytical-scale assay of mixtures of compounds containing acid chloride and/or sulfenyl chloride functionalities.The kinetics, mechanism, and stereochemistry of the dithiocarbonyl synthesis are discussed.
- Barany, George,Schroll, Alayne L.,Mott, Andrew W.,Halsrud, David A.
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p. 4750 - 4761
(2007/10/02)
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- Process for the preparation of thiocarbamic acid O-esters
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Process for the preparation of thiocarbamic acid-O-esters of the general formula EQU1 in which R1 means an alkyl or cycloalkyl radical, R2 and R3 each stands for an alkyl radical which may be substituted by one of the groups --(O--C2 H4)n --OH, --(OC2 H4)n --OCH3 or --O--(CH2)m --CH3, n being 0, 1 or 2 and m being 1 or 2, or stand for a cycloalkyl radical, and one of the radicals R2 and R3 may be hydrogen which process comprises reacting at a temperature ranging between 20° and 120°C in an aqueous or water-containing medium a xanthogenate of the formula EQU2 in which R1 is defined as above and Me is an alkali metal with a primary or secondary aliphatic amine of the formula EQU3 in which R2 and R3 are defined as above, and elementary sulfur.
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