An efficient, one-pot synthesis of trithiocarbonates from the corresponding thiols using the Mitsunobu reagent

A novel Mitsunobu-based protocol has been developed for the synthesis of a variety of symmetrical and unsymmetrical trithiocarbonates from primary, secondary and tertiary thiols using carbon disulfide, in good to excellent yields. This protocol is mild and efficient compared to other reported methods.     

Triethylamine-catalyzed one-pot synthesis of trithiocarbonates from carbon disulfide, thiols, and alkyl halides in water

Symmetrical and unsymmetrical trithiocarbonates were prepared by a simple and efficient one-pot reaction of thiols, carbon disulfide, and alkyl halides in the presence of triethylamine in water at room temperature. Correspondence: Barahman Movassagh, Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315–1618, Tehran, Iran.     

An efficient, one-pot synthesis of trithiocarbonates from alcoholic tosylates using the Cs2CO3/CS2 system

A single-step novel protocol for the preparation of symmetrical trithiocarbonates from a corresponding variety of primary, secondary, and tertiary alcoholic tosylates using the Cs₂CO₃/CS₂ system, was developed. This protocol is mild and more efficient than the reported methods.     

An efficient, one-pot, synthesis of dithiocarbamates from the corresponding alcohols using Mitsunobu’s reagent

A Mitsunobu-based protocol has been developed for the synthesis of dithiocarbamates from the corresponding alcohols using carbon disulfide and amines in good to excellent yields. This protocol is mild, chemoselective and efficient compared to other reported methods.     

Triton-B catalyzed,efficient one-pot synthesis of dithiocarbazates

A quick and efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various primary, secondary, and tert. alkyl halides with a variety of substituted hydrazines using the benzyl-trimethylammonium hydroxide (Triton-B)/CS₂ system. The reaction conditions are mild with simpler work-up procedures than the reported methods. Correspondence: Devdutt Chaturvedi, Medicinal and Process Chemistry Division, Central Drug Research Institute, Lucknow-226001, U.P., India.     

High-efficiency electrochemical CO<Subscript>2</Subscript>-to-methane reduction method using aqueous KHCO<Subscript>3</Subscript> media at less than 273 K

The electrochemical reduction of CO₂ with a Cu electrode in a KHCO₃ aqueous solution was investigated at low temperature. A divided H-type cell was employed; the electrolyte was a 1.1 mol dm^–3 KHCO₃ aqueous solution. The temperature during the electrolysis of CO₂ was reduced to 269 K. Methane, ethylene, and formic acid were obtained from CO₂ as the main products. The maximum faradaic efficiency of methane was 44% at a relatively negative potential and 269 K. The efficiency of hydrogen formation, as the competition against CO₂ reduction, significantly decreased with lowering the temperature. On the basis of this work, the high-efficiency electrochemical CO₂ to methane conversion method appears to be achieved. Electronic Publication     

Hybrid catalytic effects of K<Subscript>2</Subscript>CO<Subscript>3</Subscript> on the synthesis of salicylic acid from carboxylation of phenol with CO<Subscript>2</Subscript>

As a base-promoted Kolbe–Schmitt carboxylation reaction, the mechanism of synthesis of salicylic acid derivatives from phenols with CO₂ in the industry is still unclear, even up to now. In this paper, synthesis of 3,6-dichloro salicylic acid (3,6-DCSA) from 2,5-dichloro phenoxide and CO₂ was investigated in the presence of K₂CO₃. We show the reaction can proceed by itself, but it goes at a slower rate as well as a lower yield, compared to the case with the addition of K₂CO₃. However, the yield of 3,6-DCSA is only minorly affected by the size of K₂CO₃, which cannot be explained from the view of catalytic effect. Therefore, K₂CO₃ may on one hand act as a catalyst for the activation of CO₂ so that the reaction can be accelerated, while on the other hand, it also acts as a co-reactant in deprotonating the phenol formed by the side reaction to phenoxide, which is further converted to salicylate.     

Quantum-Chemical Study of the Profiles of Reactions that Form Pyrrole Anion N-Adducts with CS<Subscript>2</Subscript> and CO<Subscript>2</Subscript>

The profiles of reactions leading to pyrrole anion N-adducts with CO₂ and CS₂ have been studied by the ab initio (RHF/6-31+G*, MP2/6-31+G*) and density functional (B3LYP/6-31+G*) methods. Addition of the pyrrole anion to the carbon disulfide molecule is accompanied by the appearance of a minimum corresponding to a pre-reaction complex. The transformation of the complex to the N-pyrrolyldithiocarboxylate anion occurs via a low activation barrier, which is due to repolarization of the C=S bonds. The profile of the reaction leading to the pyrrole anion N-adduct with CO₂ does not contain any intermediate stationary points throughout the whole route from reagents to products.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, I. L. Zaitseva, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 990–993, November–December, 2004.     

An efficient one-pot strategy for the synthesis of 4- methylene-2-thiazolidinethiones in water

Abstract

A simple and efficient, one-pot strategy for the preparation of 4-methylene-2-thiazolidinethiones has been developed. This protocol involved condensation of primary amines with carbon disulfide in water to generate the dithiocarbamate salts in situ, which coupled with 2,3-dibromopropene, followed by intramolecular cyclization to the corresponding heterocycles in moderate to good yields.     

An efficient and general procedure for room-temperature synthesis of benzofurans under solvent-free conditions using KF/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Room temperature Rap-Stoermer condensation of α-haloacetophenone with various 2-hydroxyarylaldehydes mediated by KF/Al₂O₃ resulted in sole formation of good to excellent yields of various substituted benzofurans in the absence solvent or extra stimulant.     

Synthesis and study of the phosphate Cs<Subscript>2</Subscript>Mn<Subscript>0.5</Subscript>Zr<Subscript>1.5</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

The new phosphate Cs₂Mn_0.5Zr_1.5(PO₄)₃ was synthesized for the first time and characterized by X-ray diffraction. Its crystal structure was refined in space group P2₁3, Z = 4 at 25°C (a = 10.3163(1) Å, V = 1097.93(1) ų), by the Rietveld method using the powder X-ray diffraction data. The structure is built of an octahedral-tetrahedral framework {[Mn_0.5Zr_1.5(PO₄)₃]^2?}_3∞ with cesium atoms being located in large cavities. The hydrolytic stability of the powdered phosphate containing ¹³⁷Cs radionuclide was studied. The minimum achieved ¹³⁷Cs leaching rate was 4 × 10^?8 g/cm₂ day.     

Phase equilibria and heterogenization of supercritical fluids in the K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>CO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

This experimental study of phase equilibria in the K₂SO₄-K₂CO₃-H₂O system at 385–500°C and pressures up to 100 MPa is directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids from the homogeneous one; the homogeneous supercritical region spreads into the ternary system from the K₂SO₄-H₂O subsystem. We found that heterogenization of supercritical fluid upon addition of K₂CO₃ starts with l₁=l₂ critical phenomena in solid saturated solutions and is attended by amalgamation of the stable immiscibility region that spreads from the K₂CO₃-H₂O system with the metastable immiscibility region that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria at temperatures above the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the regions of fluid equilibria, g=l and l₁=l₂ critical phenomena, and liquid-liquid phase separation in two-, three-, and four-phase equilibria.     

Hypothetical transformation of Ca(OH)<Subscript>2</Subscript> into CaCO<Subscript>3</Subscript> in solid-state reactions of portland cement

Summary Previous study of the hydration and ageing products of two cement pastes created the basis for the postulate of the course of solid-state reactions between the portlandite Ca(OH)₂ and the CO₂ from air in the hydrated and air dry cement. XRD basal spacing d(001) of portlandite exceeded the nominal value and increased with ageing, with the wetting and drying procedure and with carbonate content of the paste, indicating that a part of OH^- ions was gradually substituted by CO₃^2- ions, which are about twice bigger. IR spectroscopy showed a considerable content of portlandite, of CO₃^2- of water and silicates. Also HCO₃^- H₂O and CO₂ in cavities between hexagonal rings and hexagonal hydrates were indicated. By MS (mass spectrometry) in vacuum the evaporation of sorbed water was detected at 100-120°C, of gel water at 350°C of portlandite water at 400°C and of high temperature water between 500 and 700°C, simultaneously with CO₂ escape. Slightly higher peak temperatures were found by the TG test either in air or in argon. From these results and from geometric considerations it is postulated that the solid-state reactions take place on ageing of the cement paste and on its heating: hexagonal portlanditecalcium carbonate hydroxy hydratecalcium carbonate hydratehexagonal vaterite and/or orthorhombic aragoniterhombohedral calcite The analysis of the standard files of the calcium carbonate hydroxy hydrates supports this postulate and indicates a gradual transformation.     

Effect of H<Subscript>2</Subscript> in the synthesis of COS using liquid sulfur and CO or CO<Subscript>2</Subscript> as reactants

The synthesis of COS from CO, CO₂ and liquid sulfur in the presence and absence of hydrogen was explored. The reaction of H₂ with liquid sulfur produced H₂S and polysulfanes, which increase the reactivity of liquid sulfur and provide alternative complementary reaction routes for the formation of COS. The reaction from CO₂ proceeds by forming CO as intermediate. Elevated pressure favors formation of COS from both carbon oxides due to the increasing residence time and the saturation of gases in the liquid. Above 350 °C, the solubility of H₂S in sulfur and the hydrogenation of COS limit the conversion of CO. The approach provides a highly efficient method for the preparation of COS under mild reaction conditions, without using a catalyst or water adsorbents.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

Structure and properties of Ce<Subscript>3</Subscript>Pd<Subscript>3</Subscript>Bi<Subscript>4</Subscript>, CePdBi,and CePd<Subscript>2</Subscript>Zn<Subscript>3</Subscript>

The intermetallic cerium compounds Ce₃-Pd₃Bi₄, CePdBi, and CePd₂Zn₃ were synthesized from the elements in sealed tantalum ampoules in an induction furnace. The compounds were characterized by X-ray powder and single crystal diffraction: CeCo₃B₂ type (ordered version of CaCu₅), P6/mmm, a = 538.4(4), c = 427.7(4) pm, wR2 = 0.0540, 115 F ² values, 9 variables for CePd₂Zn₃ and Y₃Au₃Sb₄ type, I \({\bar 4}\)3d, a = 1005.2(2) pm, w R2 = 0.0402, 264 F ² values, 9 variables for Ce₃Pd₃Bi₄, and MgAgAs type, a = 681.8(1) pm for CePdBi. The bismuthide structures are build up from three-dimensional networks of corner-sharing PdBi₄ tetrahedra with Pd–Bi distances of 281 (Ce₃Pd₃Bi₄) and 296?pm (CePdBi), respectively. The cerium atoms are located in larger voids of coordination number 12 (Ce₃Pd₃Bi₄) and 10 (CePdBi). In CePd₂Zn₃ the cerium atoms fill larger channels within the three-dimensional [Pd₂Zn₃] network with 18 (6 Pd + 12 Zn) nearest neighbors. The three compounds contain stable trivalent cerium with experimental magnetic moments of μ_eff = 2.70(2), 2.48(1), and 2.49(1) μ_B/Ce atom for CePd₂Zn₃, Ce₃Pd₃Bi₄, and CePdBi, respectively. Susceptibility and specific heat data gave no hint for magnetic ordering down to 2.1?K.     

Synthesis,characterization and photocatalytic properties of cesium tungstate (Cs<Subscript>2</Subscript>W<Subscript>3</Subscript>O<Subscript>10</Subscript>) nanofibers

In the paper cesium tungstate nanofibers for the first time have been fabricated successfully by a simple electrospinning technique followed by heat treatment. The cesium tungstate nanofibers have been characterized by XRD, SEM, and FTIR techniques. The results indicated the morphology and quality of the annealed electrospun samples are strongly dependent on the citric acid content within electrospinning solution. It is found with increasing the citric acid content from 7 to 22% the samples morphology changed from a particle structure to a fibrous structure. The average diameter of nanofibers was ~350 nm. XRD analysis reveals that all of the samples have good crystallinity with the same diffraction peaks that can be indexed to the tetragonal phase of Cs₂W₃O₁₀. Furthermore, the photocatalyst properties of cesium tungstate has not been reported to date. In the work the synthesized Cs₂W₃O₁₀ nanofibers were found to exhibit photocatalytic performance in the photodegradation of RhB aqueous solution used as a pollutant model.     

Phase equilibria in the Na,K∥SO<Subscript>4</Subscript>, CO<Subscript>3</Subscript>, F-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the Na, K∥SO₄, CO₃, F-H₂O system at 25°C are studied using the translation technique. Twenty four divariant fields, 22 univariant curves, and seven invariant points are found in the system. The complete phase diagram (the phase complex) of the system is designed on the basis of these data.     

High temperature adsorption of CO<Subscript>2</Subscript> on various hydrotalcite-like compounds

A study was conducted to describe and quantify how substitution of the divalent cation and interlayer charge compensating anions affect the CO₂ adsorptive capacity of various hydrotalcite-like compounds (HTlcs). Physical and chemical properties of the HTlcs were evaluated using a number of methods and the CO₂ adsorption rate and capacity were measured at elevated temperature (603 K). The results showed that the synthetic analogue of the naturally occurring hydrotalcite mineral, [Mg_0.73Al_0.27(OH)₂](CO₃)_0.13⋅xH₂O, had the best overall adsorption capacity and kinetics. The stability of the adsorption capacity was tested by subjecting the model HTlc to 10 equilibrium adsorption and desorption cycles. At the end of the cycle, the HTlc had maintained approximately sixty-five percent of its initial capacity. Temperature programmed desorption of CO₂ was used to quantify the surface basicity of the various HTlcs. The results showed that the reversible physisorption portion of the CO₂ isotherm was correlated to the number of surface basic sites on the HTlcs.