Sulfate Reagent Research Articles

Acid Retardation method of separation for closed-circuit processing of alumina-containing raw materials with the use of salt-acid digestion

A brief overview and critical analysis of acid and acid-salt methods for processing alumina raw materials, including high-silica bauxite, nepheline and clay is presented. The basic approaches to the creation of closed and reagent-less or low-reagent-consumption processes are demonstrated. The results obtained in the course of long-term systematic laboratory and bench studies are presented, and they display the prospects for the creation of new technologies for the production of alumina from high silica bauxite and aluminum silicates with the use of different nitrate and sulfate reagents. In the case of using acids, the sorption method of «Acid Retardation» in nano-porous media is shown to be successfully used for recycling them into the process head and to ensure soft conditions for the removal of iron components. This stage is realized with the use of strong base anion exchanger, preliminarily equilibrated with the macro-anion composition of solutions to be processed and washed with water or diluted acid solution. The AR process in three phase systems including organic liquids immiscible with water solutions (“New Chem” method) is also described, a this is also important to provide the complete insulation of concentrated salt solution and to simplify its farther treatment. A circular process with the recovery and consumption of the same amount of salt reagent in each cycle is demonstrated. A comparison of digestion methods is given in terms of the completeness of reagent recycling, the quality of product and the complexity of the process. Advisable conditions for the production of alumina from non-traditional raw with salt-acid decomposition are shown. As it is shown, the most in demand are the processes, which fully or partially can be «inscribed» in modern equipment design and process conditions corresponding to the standard Bayer method or its industrial modifications

Identifying the RNA Kinetic Traps in Ribosome Assembly

The ribosome is the cellular machine responsible for protein production in every living cell. While the final structure of the mature ribosome is known from x-ray crystallography studies, the assembly process remains largely unknown. To fulfill the cells’ demand for proteins, ribosome assembly in vivo occurs fast and efficiently. Consequently, intermediates of the assembly process are short lived and do not accumulate in large amounts for investigation. To increase the accumulation of in vivo intermediates of large subunit ribosome assembly in Escherichia coli, we take advantage of the helicase inactive DbpA construct R331A. When R331A DbpA is expressed in cells, three large subunit particles, with sedimentation coefficients of 27S, 35S, and 45S, accumulate. The particles rearrange to form the native 50S large subunit via parallel pathways. We interrogated the RNA structure of the 45S particle using dimethyl sulfate and SHAPE chemical probing reagents combined with Next Generation Sequencing. The structural probing experiments revealed perturbed secondary structures of the P-loop and the helices of the peptidyltransferase center. Additionally, it revealed an incorrect orientation of helix 38, the finger of the A-site, and several critical, broken tertiary RNA contacts between distant regions of the 23S rRNA. The data suggests the peptidyltransferase center's maturation is one of the final events during assembly. This severe misfolding explains the slow rearrangement of the 45S particle to the native 50S subunit. Next, we will characterize the RNA structure of the 27S and 35S particles. The structural probing of the 27S and 35S particles will provide insights into the early steps of ribosome assembly, which remain a complete mystery.

Screening of Activation Tools to Design Sulfated Saccharides

AbstractO‐Sulfonation of saccharides using thermal, microwave and flow chemistry activation modes is described. To this end, we studied the exhaustive monosulfation at position 4 and disulfation at positions 4,6 of several monosaccharides bearing a large variety of protecting groups. Additionally the regioselective 6‐O sulfonation of 4,6‐diol was explored. It is demonstrated that microwave and flow chemistry activation provide significant benefits compared to classical thermal O‐sulfonation, drastically reducing the reaction time and/or the amount of sulfating reagent. To prove the versatility of the strategy, one example of 6‐O‐sulfonation of a disaccharide is also reported.

Substitution of sulfate in apatite

The substitution of sulfate in apatite is of potential importance in synthetic biomaterials used in bone repair and reconstruction. The counter ion (e.g., Na + , K + , Mg 2+ , Sr 2+ ) in the sulfate reagent may also be used as a source of medically beneficial ions. An understanding of the structural parameters controlling sulfate substitution is also important in expanding our knowledge beyond the substitution of carbonate in apatites. The incorporation of sulfate in calcium and strontium hydroxylapatites, prepared in aqueous solution at pH 9, was verified by combustion analysis of sulfate, infrared and Raman spectroscopy, and by determination of unit-cell parameters. Sulfate could not be incorporated into barium hydroxylapatite because of the preferential formation of BaSO 4 . The amount of sulfate substituted in the apatite was affected by the mole ratio of sulfate to phosphate in the reaction mixture and by the nature of the counter ion in the sulfate reagent. When sodium is the counter ion in the sulfate reagent, the molar amounts of both sodium and sulfate in the product apatite can be explained by assuming charge compensation by sodium ions and sulfate displacement of phosphate and calcium. With lithium as the counter ion, a greater molar amount of lithium than sulfate is incorporated into the apatite, an observation that requires an additional charge-compensation mechanism. With potassium and rubidium as counter ions, less of the counter ion is incorporated than sulfate, probably a result of less favorable accommodation of the larger cation in the apatite structure. The maximum molar amount of sulfate incorporated in hydroxylapatite (prepared in the presence of Na + ) is more than three times lower than the maximum molar amount of carbonate that can be incorporated, a difference that can be explained by the relative solubilities of the substituted apatites. The unit-cell parameters determined for both sulfated calcium and strontium hydroxylapatites synthesized with the sodium counter ion show a slight increase in the a -axis length and a nearly constant c -axis length with increasing sulfate content. The difference in the variation of unit-cell parameters with anion content can be rationalized by the difference in size of the anion. The results indicate that sulfate can be incorporated into biomaterials such as apatite or in composites with calcium sulfate and that the design of new apatites and composites could include the use of medically desirable counter cations.

Qualitative Analysis of Test Strip for Sildenafil Citrate with Some Combinations Reagen in Cellulosa Paper Membran

Sildenafi l citrate was widely used to treat erectile dysfunction in men. The high demand of this drug, infl uence of counterfeit drugs. Therefore, it is required an analytical method to determine the authenticity of this drug. The aims of this research were to develop and evaluate of strip test for sildenafi l sitrat identifi cation. Research was conducted by preparation of solution and choosing the appropriate reagent for sildenafi l citrate. The optimum reagents were immobilized in cellulose paper followed by manufactured into strip test. Product performance was evaluated by evaluating several test in termed of qualitative, reproducibility, specifi city and response time. The results showed that the optimum membrane product was consisted of copper sulfate and sodium bicarbonate (2:1); ammonium ferric sulfate hexahydrate and copper acetat (1:3); sodium sulfate, copper acetate and ammonium ferrite sulfate (2:1:1) and mercury acetate and copper sulfate (2:1) reagents. The strip test had a capability in specifi c identify of sildenafi l citrate with a good reproducibility and less than ten seconds for time response. The strip test developed could be used as an early detection tool for the authenticity of a sildenafi l citrate tablet which more rapid.

A practical method for extending the biuret assay to protein determination of corn-based products

A modified biuret method suitable for protein determination of corn-based products was developed by introducing a combination of an alkaline reagent with sodium dodecyl sulfate (reagent A) and heat treatments. The method was tested on seven corn-based samples. The results showed mostly good agreement (P>0.05) as compared to the Kjeldahl values. The proposed method was found to enhance the accuracy of prediction on zein content using bovine serum albumin as standard. Reagent A and sample treatment were proved to effectively improve protein solubilization for the thermally-dried corn-based products, e.g. corn gluten meal. The absorbance was stable for at least 1-h. Moreover, the whole measurement of protein content only needs 15-20min more than the traditional biuret assay, and can be performed in batches. The findings suggest that the proposed method could be a timesaving alternative for routine protein analyses in corn processing factories.

Preparation, characterization and in vitro anticoagulant activity of corn stover xylan sulfates

A new anticoagulant agent was prepared by introducing sulfate groups into corn stover xylan through homogeneous reactions. Three organic solvents, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and formamide (FA), were adopted as reaction media, with the assistance of LiCl. Structural characterization by FT-IR and 13CNMR showed that xylan sulfate (XS) could be successfully synthesized with SO3∙Pyridine (SO3∙Py) complexes sulfation reagent in the three media. The effect of sulfation temperature, sulfation time, media type and molar ratio of −SO3/−OH on the degree of substitution (DS) and degree of the polymerization (DP) were studied. DMF/LiCl were more effective than DMSO/LiCl and FA/LiCl in preparation of xylan sulfate with high DS. The optimal conditions for sulfation were obtained when SO3∙Py complex was added to DMF/LiCl with −SO3/−OH ratio of 1.5:1 and maintained at 50 °C for 3 h. Degree of polymerization of xylan was decreased during the sulfation process and DMF/LiCl offered the least xylan degradation as compared with DMSO/LiCl or FA/LiCl. Anticoagulant activities of the resultant xylan sulfates with different DS were evaluated by using activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). Results indicated that the introducing of sulfate groups into xylan did endow the polysaccharides with anticoagulant activity. The APTT and TT of XS with DS of 1.20 reached 141 and 45.3 s at a dosage of 20 μg/mL, while the APTT and TT values for the blank sample were only 35.5 and 15.6 s. Furthermore, coagulation time was prolonged with the increase of DS and the concentration of XS. Our findings provide new insights into the value-added utilization of agricultural biomass.

ChemInform Abstract: Regioselective, Tin‐Free Sulfation of Unprotected Hexopyranosides by Using Phenylboronic Acid

Abstractfor masking the hydroxy groups and a 2,2,2‐trichloroethyl‐protected sulfurylimidazolium salt as the sulfating reagent

Regioselective, Tin‐Free Sulfation of Unprotected Hexopyranosides by Using Phenylboronic Acid

AbstractRegioselective, tin‐free sulfation of a number of unprotected glycopyranosides derived from L‐fucose, L‐rhamnose, D‐arabinose, D‐glucose, D‐galactose, and D‐trehalose was achieved by using phenylboronic acid for masking the hydroxy groups and a 2,2,2‐trichloroethyl‐protected sulfurylimidazolium salt as the sulfating reagent. The formation of phenylborate ester remarkably improved the solubility of the carbohydrates in organic solvents and indicated high reactivity and regioselectivity in the sulfation reactions. This methodology was successfully adapted to result in a one‐pot procedure that did not require separation or purification of the reaction intermediates.

Сорбционная очистка никелевых растворов от металлов-примесей

The paper discusses the possibility of sorption purification of nickel solutions of zinc, copper and iron in the production of nickel sulphate reagent of “Fine chemicals” grade with resins having functional groups, such as aminodiacetic (Lewatit TP207); bis-2,4,4-trimethylpentyl-phosphinic acid (Lewatit TP272); aminophosphonate (Purolite S940). The values of static (SOY) and dynamic (DOE) exchange capacity of investigated sorbents for impurity metals in technological solutions of the composition (g/dm 3 ) are defined: 147.6 Ni; 2.02 Zn; 0.36 Cu; 0.17 Fe; 9.8 H 2 SO 4 , and model binary “nickel-metal” solutions (g/dm 3 ): 75.9–88.6 Ni; 7.1 Zn; 0.52 Cu; 0.34 Fe; 4.7 H 2 SO 4 . In the static mode the increase of the ratio of volumes of the sorbent and the solution (sol/liq) leads to the increase of the metal extraction degree. When sol/liq = 0.1, the metals most completely extracted from technological solutions in resins are, in %: Cu, > 60 (TP207) and Fe(III), ≈ 50 (S940), while simultaneous sorption of other metals does not exceed 8–14 % of the original content. Sorption isotherms of metal impurities from model solutions according to values of correlation coefficients ( R 2 > 0.95) are satisfactorily described by Langmuir and Freundlich models. The use of the sorption technology does not allow to perform sufficient purification of solutions from impurity metals, which is made by the use of step extraction with D2EHPA and Versatic 10.

Sonochemical Degradation of Rhodamine B Using Oxidants, Hydrogen Peroxide/Peroxydisulfate/Peroxymonosulfate, with Fe2+ Ion: Proposed Pathway and Kinetics

Abstract This article addresses the sonochemical degradation of Rhodamine B (RB), a recalcitrant textile organic dye. The relative influence of extent of radical production by the cavitation bubbles and radical scavenging (or conservation) on the overall degradation of RB was assessed. Degradation of RB at different experimental conditions, such as pH, gases (air, argon [Ar], oxygen, and nitrogen), hydrogen peroxide (H2O2), peroxymonosulfate (PMS), peroxydisulfate (PDS), ferrous sulfate, and novel Fenton-like reagents (H2O2+ferrous sulfate, PDS+ferrous sulfate, and PMS+ferrous sulfate), was studied. Experimental results revealed that sonochemical degradation of RB is governed by the extent of utilization of HO· radicals. Ar-bubbled solution that produces higher HO· radicals gave a higher color-removal rate than other gases. Further, higher color removal was observed at solution pH of 3. Of all the experimental conditions studied, novel Fenton-like reagent, that is, PMS+ferrous sulfate-added solution, gave...

Simultaneous quantification of eight bioactive secondary metabolites from Codonopsis ovata by validated high performance thin layer chromatography and their antioxidant profile

Chemical investigation of Codonopsis ovata resulted in the isolation and identification of β-sitosterol-3-O-glycoside, luteolin, apigenin, gentiacaulein, swertiaperenine, β-sitosterol, taraxeryl-3-acetate, and 3β-acetoxyoleanane-12-one. A rapid, precise, sensitive and validated HPTLC method for simultaneous quantification of these natural products (NPs) was developed on silica-gel 60F254 plate using ternary solvent system, n-hexane:ethyl acetate:formic acid (10.5:3.5:0.43, v/v/v). Markers were quantified after post chromatographic derivatization with cerric ammonium sulfate reagent. The method was validated for accuracy, precision, LOD, LOQ and all calibration curves showed a good linear relationship (r>0.9924) within test range. Precision was evaluated by intra- and inter-day tests with RSDs <2.59%, accuracy validation recovery 92.43–99.50% with RSDs <1.00%. Apigenin was found major component (natural abundance: 1.103%) and β-sitosterol the least (0.0263%). The NPs displayed antioxidant activity with luteolin exhibiting maximum effect at 1μg/mL concentration (75.9% for DPPH and 43.7% for ABTS) and others at 10 and 25μg/mL, suggesting thereby their apparent potential use for the prevention of free radical induced diseases or as an additive element to food and pharmaceutical industry.

Development of a laboratory test to characterise the behaviour of free gold for use in a combined flash flotation and gravity concentrator model

Currently there is no process model which simulates the behaviour of gravity recoverable gold (GRG) in flash flotation unit operation. Once developed, such a flash float model could be incorporated into an existing model for gravity concentration. Together, the integrated gravity recovery-flash float model will provide a tool for predicting the recovery of GRG in a closed milling circuit using both batch centrifugal concentration and flash flotation. In order to design a flash flotation model, a reliable laboratory method to characterise the response of GRG when subjected to flash flotation conditions has been developed. This paper details the evaluation of the effects of various chemical (reagent concentrations, sulfide presence, etc.) and operational (airflow, agitation, etc.) parameters on the overall GRG recovery by lab scale flash flotation. Of the factors evaluated, free gold flotation was found to be most impacted by potassium amyl xanthate (PAX) and copper sulfate reagent levels, as well as agitation speed and sulfide mineral additions.

Sulfation of β-resorcylic acid esters—first synthesis of zearalenone-14-sulfate

Abstract The chemical sulfation of β-resorcylic acid esters was investigated by applying state of the art procedures for the synthesis and deprotection of 2,2,2-trichloroethyl protected sulfates as appropriate intermediates. The selectivity of monosulfation was studied and reaction optimization was performed considering the effect of the solvent, different bases as well as the sulfation reagent itself. Finally the obtained protocols were applied for the first synthesis of zearalenone-14-sulfate (ammonium salt), an important conjugated (masked) mycotoxin, as reference material for further investigations in the field of bioanalytics as well as toxicology.

Novel gastroulcer protective micro(hydro)gels of sulfated locust bean gum-aluminium complex for immediate release of diclofenac sodium

In this study, carboxymethyl sulfate derivative (CLBS) of locust bean gum (LBG) was synthesized by varying the strength of sulfating reagent. CLBS was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and viscosity measurements. Furthermore, the degree of sulfation and carboxymethylation in CLBS was determined. Novel micro(hydro)gel particles of CLBS were fabricated in basic aluminum chloride solution and different concentration of diclofenac sodium was incorporated into these particles. Differential scanning calorimetry and FTIR analyses did not suggest any drug-polymer interaction. Spherical morphological structures of the particles were evident under scanning electron microscope. Regardless of the formulation variables, a maximum of ~60% drug entrapment efficiency was achieved. For a higher degree of substitution, CLBS particles disintegrated rapidly (~20 min) and released >80% drug in acidic medium (pH1.2 and pH4.0) in 60 min. However, the particles liberated only ~60% drug in phosphate buffer medium (pH6.8) during this period. Following disintegration of the particles, the pH of gastric environment elevated. In stomach histopathology, the ulcers were scored and it was estimated that CLBS afforded ~86% protection to the gastric mucosa from ulceration. Thus, the micro(hydro)gel particles of CLBS-aluminium complex could be useful for immediate analgesic effect of the drug without any significant gastric distress.

Optimized Thin Layer Chromatographic Method for Screening Pharmaceutically Valuable Alkaloids of Catharanthus roseus (Madagascar Periwinkle)

The aerial parts of Catharanthus roseus (C. roseus) plant have been known to contain many important alkaloids such as Vincristine, Vinblastine, Vindoline and Ajmalicine which are of interest to this study. Ajmalicine has also been found in abundance in the roots of this medicinal plant. The main objective of this study was to screen a methanolic extract of C. roseus for the presence of pharmaceutically valuable alkaloids using previously optimized conditions established in our laboratory set up.This methanolic extract was further purified for specific alkaloids present using modified Shams et al. (2009) method I extraction procedure. Extracts of C. roseus have been subjected to optimum conditions before and after Thin layer Chromatography which was performed in a trough chamber of 10 cm x 10 cm area saturated with Ethyl acetate: Benzene: Methanol: 25% Ammonia solution (100:5:5:3) as a developing solvent and sprayed with Cerium Ammonium Sulphate (CAS) reagent specific for the detection of alkaloids.Results have shown that the alkaloids of interest; Vincristine, Vinblastine, Vindoline and Ajmalicine could be chromatographically identified in extracts of C. roseus intact plant after individual alkaloid purification procedure. This has confirmed the anti-neoplastic and anti-hypertensive properties these alkaloids have in making the plant effective in healing cancer and high blood pressure as it was originally used by traditional people.

Synthesis and characterization of microporous polymer microspheres with strong cation-exchange character

In this paper the synthesis and characterization of microporous polymer microspheres with ultra-high specific surface areas (>1000m2/g) and strong cation-exchange character is described. The microspheres were synthesized by the hypercrosslinking of swellable precursor particles which had been produced by precipitation polymerization. The strong cation-exchange character, arising from the presence of sulfonic acid groups, was introduced through post-hypercrosslinking chemical modification reactions. Two alkyl sulfate reagents of differing polarity were compared as reagents for the sulfonation reactions, and a synthetic methodology was devised that allowed the sulfonic acid content of the microspheres to be controlled. Following a series of small-scale optimization experiments, optimized conditions were applied on a larger scale to the synthesis of three distinct polymers (HXLPP-SCX) tailored for use as strong cation-exchange (SCX) sorbents in solid-phase extraction (SPE) studies. All three polymers were in the form of polymer microspheres (mean particle diameters 3–5μm) with relatively narrow particle size distributions and specific surface areas up to 1370m2/g, and had tuneable ion-exchange capacities (IECs) ranging from 1.7–2.8mmol/g.

Synthesis, characterization, and anticoagulant activity of carboxymethyl starch sulfates

AbstractTo develop a renewable and compatible anticoagulant as potential heparin alternative, carboxymethyl starch sulfate (CMSS) was prepared by the reaction of carboxymethyl starch (CMS) and sulfating reagent [N(SO3Na)3]. The chemical structures of CMS and CMSS were characterized by Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance. The influences of reaction parameters, including the pH of sulfating reagent, the molar ratio of sulfating reagent to CMS, reaction time, and temperature on the degree of substitution of sulfate groups (DS) of CMSS were studied. Meantime, the DS of each CMSS was determined by barium sulfate–glutin nephelometery method. Moreover, the anticoagulant activity of CMSS was investigated by the coagulation assays of activated partial thromboplastin time, thrombin time, and prothrombin time. The results revealed that the anticoagulant activity of CMSS was closely related to the DS value and concentration. The anticoagulant activity was promoted with the increasing of the DS and concentration. The molecular weight (Mw) in measured range had little impact on anticoagulant activity in contract to the DS and concentration. In this article, the CMSS with the DS of 1.91, concentration of 75 μg/mL and the Mw of 2.61 × 104 had the best blood anticoagulant activities. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Sulfated zirconia as a robust superacid catalyst for multiproduct fatty acid esterification

Sulfated zirconia catalysts obtained by employing chlorosulfuric acid show significantly higher activity in the esterification of fatty acids with different alcohols compared with catalysts made using sulfuric acid. The superior performance results from higher sulfur content, larger pores and stronger acid sites. These catalysts are robust and do not leach out sulfonic groups. Catalyst performance depends strongly on the sulfation reagent and the calcination conditions of the intermediate zirconium hydroxide. A series of kinetic experiments was carried out with lauric acid and various alcohols (methanol, 2-ethylhexanol, propanols and butanols). The new catalysts are ca. five times faster when using primary alcohols independent of the alcohol chain length. When using secondary and tertiary alcohols the reaction rate drops considerably. This is explained by a linear free energy relationship of substituent reactivity. The kinetic investigation shows that chlorosulfated zirconia is suitable as a multiproduct catalyst for manufacturing fatty esters, by employing a catalytic reactive distillation process.

Simultaneous quantification of five marker compounds of Betula utilis stem bark using a validated high‐performance thin‐layer chromatography method

A sensitive, selective and robust densitometric high-performance thin-layer chromatographic method was developed and validated for five marker compounds, namely betulin, lupeol, oleanolic acid, 3-acetyloleanolic acid and β-sitosterol, known for their various therapeutic activities. The marker compounds have been isolated from the stem bark of Betula utilis, well characterized by the spectral analysis, and their simultaneous quantitative determination carried out by high-performance thin-layer chromatography (HPTLC) method. The resolution of marker compounds was carried out on silica-gel 60 plates, using n-hexane:ethyl acetate (8:2 v/v) as the mobile phase. The HPTLC densitometry was performed at 500-nm wavelength after the post chromatographic derivatization with ceric ammonium sulfate reagent. The optimized method provided good linear relation (r>0.9960) for all the investigated analytes. The method is simple, and reproducible, which may be applied for quantitative analysis of the above-mentioned marker compounds.