Synthesis,characterisation and thermal decomposition of double sulfate

Upon evaporation at room temperature of an aqueous mixture containing Al(III) sulfate and trishydroxymethyl-ammoniummethane sulfate in a molar ratio 1:2, double sulfate as crystalline product was obtained. The stoichiometry of the obtained compound was determined by means of elemental and TG analysis. For identification, IR-spectra and X-ray powder diffraction patterns were done. It was found that the general formula of the obtained compound is Al(HOCH₂)₃CNH₃(SO₄)₂·₆H₂O. as revealed by TG, DTG and DTA analysis, the dehydration of the AL-compound takes place in one step which points out that the six water molecules are bonded in the same way. The thermal decomposition of the anhydrous compound starts at about 260°C and is very complex. This process takes place in many steps which are not well resolved. The pathway of the thermal decomposition is also supposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Intercalation of dodecyl sulfate into layered double hydroxides

The intercalation of sodium dodecyl sulfate and exchange of dodecyl sulfate anion into layered double hydroxides has been examined by means of X-ray diffraction, infrared and thermogravimetric procedures. Three types of derivatives were obtained having mean interlayer spacings of 26 Å, 36 Å and 47 Å, respectively. These interlayer distances did not correlate with the amount of organic incorporated between the layers but, as shown by computer simulations, depended upon the orientation of the chains within the interlamellar space. In several reactions both intercalation of neutral sodium dodecyl sulfate as well as exchange of the dodecyl anion took place. Attempts to remove the alkyl sulfate chains with dilute acid resulted in dissolution of the more basic metals producing non-stoichiometric layered products.     

Rheological properties of sulfate cellulose

Rheological properties of concentrated aqueous solutions of sulfate cellulose prepared by various sulfation methods were studied. Information on the variation of structure of the concentrated solutions under action of external forces during viscous current depending on sulfate cellulose molecular parameters was obtained.     

Hydrophilic-oleophilic properties of sulfate lignin

Effects of extractive resinous substances, type of wood, and pH on the hydrophilic-oleophilic behavior of solid lignin recovered from sulfate delignification liquors were evaluated.     

Ion mobility,phase transitions,and ion transport in potassium-ammonium hexafluorozirconates

The mobility of fluoride and ammonium ions (180–480 K) in compounds K_{2? n} (NH4)_nZrF₆ (0.2 ≤ n ≤ 1.70) was investigated by ¹⁹F and ¹H NMR. Correlations have been found between the composition of the cation sublattice, the character of ion motions, and phase transition temperature in these compounds. The hightemperature modifications with n ≥ 0.85 of the compounds are characterized by translational diffusion of fluoride and ammonium ions and by uniaxial anisotropy of the ¹⁹F magnetic shielding tensor. The electrophysical characteristics of these compounds were studied in the temperature range 300–480 K.     

Hydrodynamic and surfactant properties of sulfate lignin solutions

The effect of low-molecular-weight electrolyte additions on the behavior of sulfate lignins in aqueous media was studied by capillary viscometry, tensiometry, and dynamic light scattering.     

Synthesis and properties of tetrazole-containing double polymers

Based on poly(5-vinyltetrazole) and a copolymer of 2-methyl-5-vinyltetrazole with 2-(vinyloxyethoxy)methyloxirane, tetrazole-containing network double polymers capable of gelation both in organic media and in water have been obtained. It has been shown that the covalent bonding of linear polymer macromolecules is the result of alkylation of unsubstituted N-H tetrazole cycles of poly(5-vinyltetrazole) with oxirane cycles incorporated into the copolymer structure.     

Production and properties of polyacenaphthylene

Summary To produce standards for GPC calibration, oligomers of polyacenaphthylene were fractionated by the method of repeated sample injection in an analytical GPC unit (-styragel-columns, eluent THF). It is possible to separate about 2 g polymers in 24 hours into fractions with good uniformity.First communication: Jürgen Springer, Tin Win, Die Darstellung von Oligoacenaphthylenen mit funktionellen Endgruppen, Makromol. Chem.179, 29 (1978).     

Synthesis and characterization of Cd-Cr and Zn-Cd-Cr layered double hydroxides intercalated with dodecyl sulfate

Cd-Cr and Zn-Cd-Cr layered double hydroxides (CdCr-LDH and ZnCdCr-LDH) containing alkyl sulfate as the interlamellar anion have been prepared through a coprecipitation technique. The resulting compounds were characterized using X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Magnetic property measurements indicate that antiferromagnetic interactions occur between the chromium ions in the two compounds at low temperatures. The introduction of zinc influences the ligand field of Cr^III and the Cr^III-Cr^III interactions in the LDH compound. It is found that both CdCr-LDH and ZnCdCr-LDH can be delaminated by dispersion in formamide, leading to translucent and stable colloidal solutions.     

Preparation and properties of chitosan chondroitin sulfate complex microcapsules

The chitosan (CHS) chondroitin sulfate (CS) complex microcapsules were prepared by emulsion-chemical crosslink method, with the chitosan and chondroitin sulfate as the wall materials and the low molecular weight heparin (LMWH) as the core materials. The microcapsules were characterized by Fourier transform infrared (IR) spectrometry, scanning electron microscope (SEM), size distribution and thermal analysis. The in vitro drug release behavior of the microcapsules was studied by spectrophotometry. The SEM and size distribution showed that the microcapsules were in the spherical form mostly in the size range of 20-80 microm. The IR spectrum indicated that there were electrostatic interactions between chitosan and chondroitin sulfate, with the sulfate group and free carboxyl group reacted with the amino groups of chitosan. The DSC result showed that the wall materials could protect the core materials of the microcapsules. The results of the release kinetics experiments of the microcapsules showed that the drug released slightly faster in acid media than in alkali ones.     

Syntheses of sulfur and selenium analogues of pachastrissamine via double displacements of cyclic sulfate

Bioisosteric analogues of pachastrissamine that contain sulfur and selenium atoms replacing the oxygen in the ring system, were efficiently prepared from a cyclic sulfate intermediate by sequential intermolecular and intramolecular S(N)2 displacement reactions of the dianions. The analogues exhibited cytotoxicities comparable to that of pachastrissamine.     

Magnetic properties of nickel and zinc double hydroxides

Magnetic properties of nickel and zinc double hydroxides were studied using an axial extraction apparatus and a Faraday balance. Measurements were taken mainly between 4.2 and 40 K for applied fields 50-45 000 Oe.The results confirm the existence of two types of structure α and β, which were previously determined by X-ray analysis.The β solids, i.e., with a low zinc concentration, are essentially antiferromagnetic at 4.2 K for fields smaller than 45 kOe. They are compared with the hydroxide β-Ni(OH)₂. The α solids are metamagnetic with a low threshold field. The magnetization isotherms obtained for the α solids at 4.2 K show magnetic viscosity phenomena.This difference in magnetic behaviour is useful for attributing the α or β structure to samples in which the phase containing the double hydroxide is not detected by X-ray analysis.     

Synthesis and electrochemical properties of double lithium-titanium phosphate

Method for synthesis of double lithium-titanium phosphate is suggested. The method includes mechanical activation of the precursor and makes it possible to reduce the temperature and shorten the annealing duration when reaching a highly dispersed state of the substance. Application of this method provides a substantial advantage in the discharge potential, capacity, and stability for electrodes of a lithium battery.     

Synthesis and properties of CaAl-layered double hydroxides of hydrocalumite-type

CaAl-layered double hydroxides (CaAl-LDHs) with various carbonate ion contents are essentially formed in Bayer liquors during the causticisation step in alumina production. Under well-defined conditions hemicarbonate is formed, which is beneficial in the process of retrieving both Al(OH) ₄ ^? and OH^? ions. In the current work, Ca₂Al-LDHs with various carbonate contents were prepared by the co-precipitation procedure and the products were dried in different ways. Structural information was obtained by a variety of methods, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Elemental maps were constructed through a combination of SEM images and EDX measurements. The targeted CaAl-hydrocalumites were successfully synthesised. It was found that the method used for drying did not influence the basal spacing although it significantly altered the particle sizes.     

Fluorosulfonyl-containing heterocyclic compounds ii properties of hexafluoroisobutenylidene sulfate

The reactions of hexafluoroisobutenylidene sulfate with tertiary amines, ethers, sulfolane, and alkali metal halides were studied. Hexafluorodimethylketene is liberated, and the reagent is sulfotrioxidized during the reaction of hexafluoroisobutenylidene sulfate with these nucleophilic compounds. Hexafluoroisobutenylidene sulfate is an electrophilic compound of the quasicomplex type, which contains a labile sulfotrioxide grouping.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 306–309, March, 1972.     

Production of potassium sulfate from potassium hydrosulfate solutions using alcohols

Potassium sulfate is used to produce multicomponent fertilizers, free of chlorides. The desalting out of potassium sulfate from an aqueous solution of potassium hydrosulfate was conducted using 40 mass %, 45 mass %, or 50 mass % aqueous solutions of either methanol or propan-2-ol. Composition of the resultant precipitate was analyzed using chemical methods and XRD analysis. The results of the XRD analysis revealed that the main precipitate phase is K₂SO₄. Small amounts of K₅H₃(SO₄)₄ were detected when the desalting out was carried out from 2.5 M KHSO₄ solution using 40 mass % and 50 mass % methanol solution. When the amount of potassium bisulfate in the solution increased to 3.5 M and 3.8 M, the main phase consisted of K₃H(SO₄)₂. Generally, the desalting out process using propan-2-ol caused the formation of K₃H(SO₄)₂. Potassium sulfate was obtained only by desalting out the 2.5 M KHSO₄ solution using 50 mass % aqueous propan-2-ol. Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May 2007.     

Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc-iron layered double hydroxides by one-step coprecipitation route

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Mössbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO₄²⁻-containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO₄²⁻-containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn_0.435·Fe^II_0.094·Fe^III_0.470·(OH)₂]·(SO₄²⁻)_0.235·1.0H₂O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO₄²⁻-containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS.     

Effect of counterions on surface and foaming properties of dodecyl sulfate

The influence of counterions of surfactant on interfacial properties is studied by measuring foamability, foam stability, equilibrium and dynamic surface tension, and surface viscosity. The surfactant chosen is anionic dodecyl sulfate with various counterions, Li(+), Na(+), Cs(+), and Mg(++). Surface tension measurements show a decrease in the following order: LiDS > NaDS > CsDS > Mg(DS)(2). Foamability done using shaking method shows similar order as surface tension, i.e., LiDS > NaDS > CsDS > Mg(DS)(2). This has been explained in terms of the differences in micellar stability and diffusion of monomers. This is further confirmed by our dynamic surface tension results, which show the same order as equilibrium surface tension (i.e., LiDS > NaDS > CsDS > Mg(DS)(2)) at low bubble frequencies but the order is LiDS > NaDS = Mg(DS)(2) > CsDS at high bubble frequencies. Foam stability measurements were done at concentrations below and above cmc to elucidate the role of micelles. It was found that there is no significant change in foam stability when counterions are changed for surfactant concentration values below the cmc, but at concentration above cmc the foam stability of CsDS and Mg(DS)(2) are much greater than LiDS and NaDS indicating presence of stable micelles are essential to high foam stabilities. Surface viscosity measurements correlated well with the foam stability trends and gave the following order LiDS < NaDS < CsDS < Mg(DS)(2), indicating that the molecules of CsDS and Mg(DS)(2) are tightly packed at the air/water interface.