- Photocatalytic H2-Evolution by Homogeneous Molybdenum Sulfide Clusters Supported by Dithiocarbamate Ligands
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Irradiation at 460 nm of [Mo3(μ3-S)(μ2-S2)3(S2CNR2)3]I ([2a]I, R = Me; [2b]I, R = Et; [2c]I, R = iBu; [2d]I, R = CH2C6H5) in a mixed aqueous-polar organic medium with [Ru(bipy)3]2+ as photosensitizer and Et3N as electron donor leads to H2 evolution. Maximum activity (300 turnovers, 3 h) is found with R = iBu in 1:9 H2O:MeCN; diminished activity is attributed to deterioration of [Ru(bipy)3]2+. Monitoring of the photolysis mixture by mass spectrometry suggests transformation of [Mo3(μ3-S)(μ2-S2)3(S2CNR2)3]+ to [Mo3(μ3-S)(μ2-S)3(S2CNR2)3]+ via extrusion of sulfur on a time scale of minutes without accumulation of the intermediate [Mo3S6(S2CNR2)3]+ or [Mo3S5(S2CNR2)3]+ species. Deliberate preparation of [Mo3S4(S2CNEt2)3]+ ([3]+) and treatment with Et2NCS21- yields [Mo3S4(S2CNEt2)4] (4), where the fourth dithiocarbamate ligand bridges one edge of the Mo3 triangle. Photolysis of 4 leads to H2 evolution but at ~25% the level observed for [Mo3S7(S2CNEt2)3]+. Early time monitoring of the photolyses shows that [Mo3S4(S2CNEt2)4] evolves H2 immediately and at constant rate, while [Mo3S7(S2CNEt2)3]+ shows a distinctive incubation prior to a more rapid H2 evolution rate. This observation implies the operation of catalysts of different identity in the two cases. Photolysis solutions of [Mo3S7(S2CNiBu2)3]+ left undisturbed over 24 h deposit the asymmetric Mo6 cluster [(iBu2NCS2)3(μ2-S2)2(μ3-S)Mo3](μ3-S)(μ3-η2,η1-S′,η1-S″-S2)[Mo3(μ2-S)3(μ3-S)(S2CNiBu2)2(μ2-S2CNiBu2)] in crystalline form, suggesting that species with this hexametallic composition and core topology are the probable H2-evolving catalysts in photolyses beginning with [Mo3S7(S2CNR2)3]+. When used as solvent, N,N-dimethylformamide (DMF) suppresses H2-evolution but to a greater degree for [Mo3S4(S2CNEt2)4] than for [Mo3S7(S2CNEt2)3]+. Recrystallization of [Mo3S4(S2CNEt2)4] from DMF affords [Mo3S4(S2CNEt2)4(η1,κO-DMF)] (5), implying that inhibition by DMF arises from competition for a Mo coordination site that is requisite for H2 evolution. Computational assessment of [Mo3S4(S2CNMe2)3]+ following addition of 2H+ and 2e- suggests a Mo(H)-μ2(SH) intermediate as the lowest energy species for H2 elimination. An analogous pathway may be available to the Mo6 cluster via dissociation of one end of the μ2-S2CNR2 ligand, a known hemilabile ligand type, in the [Mo3S4]4+ fragment.
- Fontenot, Patricia R.,Shan, Bing,Wang, Bo,Simpson, Spenser,Ragunathan, Gayathri,Greene, Angelique F.,Obanda, Antony,Hunt, Leigh Anna,Hammer, Nathan I.,Webster, Charles Edwin,Mague, Joel T.,Schmehl, Russell H.,Donahue, James P.
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- Method for preparing tetrabenzyl thiuram disulfide
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The invention belongs to the technical field of rubber auxiliary production, and relates to a method for preparing a disulphide tetrabenzyl thiuram disulfide. The method comprises the following steps: sequentially adding water, an aqueous sodium hydroxide solution and dibenzylamine in a reactor, adding a dispersing agent, and then dropwise adding carbon disulfide to perform condensation reaction to obtain the dibenzyldithioformate solution. The sodium dibenzyldithioformate solution is subjected to oxidation reaction and then filtered and dried to obtain a thiurylthiuram disulfide. In the condensation reaction process, the dispersing agent is added, the reaction system forms a uniform state, the reaction process is carried out in a uniform system, two-phase reaction is avoided when carbon disulfide is added dropwise in the prior art, and the reaction effect is poor. COD In the waste water is low, easily waste water treatment. The obtained disulfide tetrabenzylthiuram product has the appearance of white powder and the purity 98% or more.
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Paragraph 0008; 0023-0026; 0027-0031; 0032-0045
(2021/11/21)
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- Method for preparing tetraalkyl thiuram disulfide through photocatalytic oxidation
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The invention relates to a method for preparing tetraalkyl thiuram disulfide by photocatalytic oxidation. The method comprises the following steps: carrying out mixed reaction on secondary amine, carbon disulfide and a catalyst in a medium to generate an intermediate product; and carrying out catalytic oxidation reaction on the intermediate product under illumination to obtain tetraalkyl thiuram disulfide. According to the invention, the method is high in reaction speed and mild in condition, and energy conservation and efficiency improvement are achieved; the used medium and catalyst can be recycled, so that the resource utilization rate is improved; and the method does not produce inorganic salt by-products, and the product has high yield and high purity.
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Paragraph 0095-0111
(2021/02/13)
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- Continuous-flow step-economical synthesis of thiuram disulfidesviavisible-light photocatalytic aerobic oxidation
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A continuous-flow photocatalytic synthesis of the industrially important thiuram disulfides has been developed, utilizing O2as the oxidant and Eosin Y as the photoredox catalyst. This highly atom- and step-economical method features much reduced reaction time as well as excellent product yield and purity, making it a sustainable and potentially scalable process for industrial production.
- Xu, Hao-Xing,Zhao, Ze-Run,Patehebieke, Yeersen,Chen, Qian-Qian,Fu, Shun-Guo,Chang, Shuai-Jun,Zhang, Xu-Xu,Zhang, Zhi-Liang,Wang, Xiao
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supporting information
p. 1280 - 1285
(2021/02/26)
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- Synthesis process of tetrabenzylthiuram disulfide
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The invention provides a synthesis process of tetrabenzylthiuram disulfide. The synthesis process comprises the following steps: carrying out a mixed reaction on dibenzylamine and carbon disulfide inwater to generate an intermediate product, and carrying out an oxidation reaction on the intermediate product and hydrogen peroxide to prepare tetrabenzylthiuram disulfide. According to the process, water is used as a medium, so operation safety is high, no organic solvent is left in the product, and no inorganic salt by-product is generated; and the competitive reaction of the raw materials and the intermediate is effectively reduced, so product yield is improved.
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Paragraph 0018-0040
(2020/05/01)
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- Disulfiram as a potent metallo-β-lactamase inhibitor with dual functional mechanisms
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We report a promising NDM-1 inhibitor, disulfiram, which can covalently bind to NDM-1 by forming an S-S bond with the Cys208 residue. Its copper-containing metabolite in vivo, Cu(DTC)2, also inactivated NDM-1 through oxidizing the Zn(ii) thiolate site of the enzyme, therefore exhibiting dual functional inhibitory potential against B1 and B2 subclass MβLs.
- Chen, Cheng,Li, Jia-Qi,Sun, Le-Yun,Wu, Lin-Yu,Yang, Ke-Wu
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supporting information
p. 2755 - 2758
(2020/03/17)
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- Accelerant TBzTD and synthesis process thereof
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The invention belongs to the field of rubber additives and particularly relates to an accelerant TBzTD and a synthesis process thereof. The synthesis process comprises the following steps: (1) mixingdibenzylamine with alkaline liquid, dropwise adding carbon disulfide and reacting at the temperature of 30-60 DEG C to obtain dibenzyldithiocarbamic acid sodium salt, wherein a molar ratio of the dibenzylamine to the alkaline liquid to the carbon disulfide is 1 to (1-2) to (1-2); (2) mixing and stirring the dibenzyldithiocarbamic acid sodium salt obtained in the step (1) with dimethylsulfoxide anda dispersant, dropwise adding a strong acid catalyst, and reacting at the temperature of 30-80 DEG C, wherein a molar ratio of the dibenzyldithiocarbamic acid sodium salt to the dimethylsulfoxide tothe strong acid catalyst is 2 to (1-1.8) to (2-4), wherein the molar quantity of the catalyst is metered by hydrogen ions; and generating a target product TBzTD. The product yield of the reaction canreach 95% or above; through HPLC test of the product TBzTD, the purity of TBzTD can reach up to 96%; the initial melting point of TBzTD is higher than or equal to 128 DEG C.
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Paragraph 0028; 0029; 0031; 0032; 0034; 0035
(2019/03/25)
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- Tetrabenzylthiuramdisulfide synthesis method
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The present invention relates to a synthesis method of a rubber vulcanization accelerator tetrabenzylthiuramdisulfide. The synthesis method is characterized in that dibenzylamine, carbon disulfide, sodium hydroxide and hydrogen peroxide are adopted as base raw materials, and in the presence of a phase transfer catalyst, the mixture obtained from the reaction is subjected to acid neutralization, filtration, washing and drying to obtain the tetrabenzylthiuramdisulfide. According to the present invention, the method is different from the previous method using the organic solvent as the reaction system or carrying out the catalysis reaction under the pressure condition, and has characteristics of simpleness, easy operation, convenient reaction product separation and washing, high product yield, and high product purity.
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Paragraph 0016
(2016/10/10)
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- Rubber accelerator tetrabenzylthiuram disulfide method for the synthesis of
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The invention discloses a synthetic method of a rubber accelerator tetrabenzylthiuram disulfide. The method comprises the following steps: dripping carbon disulfide under the condition at 0-20 DEG C for 1.5-2 hours after mixing a solvent with dibenzyl amine, stirring and reacting for 1-3 hours, and heating to 40-70 DEG C; slowly introducing in compressed air below the liquid level of a reactant to carry out oxidization reaction, wherein the reaction time is 4-8 hours; carrying out filter pressing on the product after reacting, recycling the solvent in a filtrate; and drying a filter cake in vacuum, so as to obtain the tetrabenzylthiuram disulfide, wherein the solvent is a mixture of methanol, ethanol and toluene according to the molar ratio of 1:8:1. The method disclosed by the invention is simple and convenient in process, low in raw material cost, and free of wastewater, the solvent can be recycled after being recovered, and the product is high in yield, and high in purity.
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Paragraph 0022-0023
(2017/03/17)
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- Reduced graphene oxide as recyclable catalyst for synthesis of Bis(aminothiocarbonyl)disulfides from secondary amines and carbon disulfide
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The reaction of secondary amines with CS2 under mild conditions using reduced graphene oxide (rGO) as a green catalyst was reported, which provided an efficient access to the one-pot synthesis of bis(aminothiocarbonyl) disulfides. The rGO can be recycled at least four times without any loss of catalytic activity. A plausible mechanism was proposed.
- Wang, Meishuang,Song, Xianghai,Ma, Ning
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p. 1233 - 1239
(2014/07/21)
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- Cerium ammonium nitrate-catalyzed aerobic oxidative coupling of dithiocarbamates: Facile synthesis of thioureas and bis(aminothiocarbonyl)disulfides
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Diverse disubstituted and trisubstituted thioureas were synthesized by the condensation of dithiocarbamate TEA (or DABCO) salts and amines using cerium ammonium nitrate (CAN) as a catalyst in high yields at room temperature. It is a one-pot method and it is unnecessary to isolate isothiocyanates. This reaction probably took place through nucleophilic addition of amines to isothiocyanates, which were generated by oxidative coupling of dithiocarbamates and the following decomposition of bis(aminothiocarbonyl)disulfides. When secondary amines and CS2served as the reactants, bis(aminothiocarbonyl)disulfides were obtained via tandem nucleophilic addition/oxidative coupling reactions in moderate to excellent yields. In all the coupling reactions, the oxidant was air and CAN possibly acted as an SET catalyst.
- Li, Tian-Tian,Song, Xiang-Hai,Wang, Mei-Shuang,Ma, Ning
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p. 40054 - 40060
(2014/12/10)
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- Bis(dialkylaminethiocarbonyl)disulfides as potent and selective monoglyceride lipase inhibitors
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Monoglyceride lipase (MGL) inhibition may offer an approach in treating diseases in which higher 2-arachidonoyglycerol activity would be beneficial. We report here the synthesis and pharmacological evaluation of bis(dialkylaminethiocarbonyl)disulfide derivatives as irreversible MGL inhibitors. Inhibition occurs through interactions with MGL C208 and C242 residues, and these derivatives exhibit high inhibition selectivity over fatty acid amide hydrolase, another endocannabinoid-hydrolyzing enzyme. 2009 American Chemical Society.
- Kapanda, Coco N.,Muccioli, Giulio G.,Labar, Geoffray,Poupaert, Jacques H.,Lambert, Didier M.
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experimental part
p. 7310 - 7314
(2010/07/14)
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- Method for preparing stearically hindered aryl phosphites
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A new process is disclosed for the manufacture of hindered aryl phosphites using derivatives of mercaptothiazole or dithiocarbamic acid as catalysts. Ortho-tertiary alkyl aryl phosphites are produced by the reaction of a phosphorus trihalide with an ortho-tertiary alkyl phenolic compound in the presence of the aforementioned catalysts.
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- The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes
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The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by 3- and 11 other substitution inert metal complexes have been investigated.Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step.A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple.For diethyldithiocarbamate, Edeg(edtc./edtc-) = 425+/-33 mV ν.s.c.e. and the outer-sphere electron self-exchange rate constant is logkex = 7.0+/-0.3.A comparison with thiophenolate oxidation is also given.
- Nichols, Peter J.,Grant, Michael W.
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p. 1085 - 1102
(2007/10/02)
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- Reduction Potentials of Thiuram Disulfide/Dithiocarbamate Couples in Acetone/Water
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Reduction potentials relative to the saturated calomel electrode, Eo, of a series of thiuram disulfide/dithiocarbamate couples have been measured in 30percent v/v water in acetone and at μ 0.2 mol l-1 (NaNO3) by a combination of potentiometric measurements and equilibrium constant determinations for thiolate/disulfide interchange reactions.Eo values lie in the range -250 to -340 mV which place dithiocarbamates as intermediate between thiophenolate (Eo -540 mV) and ethylxanthate (Eo -206 mV) in reducing properties.The significant effect on Eo of varying the substituents on the nitrogen in the dithiocarbamates correlates with the substituent effects on the acid dissociation constants of the parent dithiocarbamic acid and with trends in the half-wave potentials for metal-based oxidation and reduction of transition metal dithiocarbamate complexes.
- Nichols, Peter J.,Grant, Michael W.
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p. 2455 - 2463
(2007/10/02)
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