A New Route for the Synthesis of Alkali Polyphosphate from Economical Starting Materials: Part II—Influence of Reaction Conditions

Abstract

Direct synthesis of sodium cyclotriphosphate, Na₃P₃O₉ (SCTP), from sodium chloride and orthophosphoric acid as economical starting materials was investigated. Reaction conditions including the heating rate, reaction plateau time, air flow rate, and Na/P molar ratio were found to be key parameters for the elimination of chloride and for the selectivity in SCTP. High yields in SCTP (94–99%) were obtained. The results are very interesting with respect to a potential industrial application for the synthesis of SCTP from point of view of the low cost of the starting materials.     

Crystalline Intermediates during Polycondensation Reactions in the C–N–Cl System – The Paddle‐Wheel Molecule N(C6N7Cl2)3

Solid state metathesis reactions between cyanuric chloride and C–N–H or alkali metal–(B–)C–N compounds, respectively, were carried out in the temperature range between 150 °C to 500 °C, studying intermediate stages of reactions and targeting the formation of carbon nitride materials by elimination of HCl or alkali metal chlorides. Although cyanuric chloride was reacted with quite a number of different reaction partners such as melamine, cyanamide, lithium nitride, lithium or sodium carbodiimide, lithium nitridoborate or sodium dicyandiamide, always the same intermediate compounds appeared in the reactions mixtures. Colorless, needle‐shaped crystals of the tertiary amine N(C₃N₃Cl₂)₃ ( 1 ) were obtained at temperatures around 200–250 °C. Temperatures as high as 400 °C yielded yellow, plate‐like crystals of the heptazine compound C₆N₇Cl₃ ( 2 ). At even higher temperatures, the reaction products were of poorer crystallinity, but evidence of the formation of another crystalline intermediate was given by X‐ray powder diffraction and electron diffraction experiments. This third intermediate is assumed to be a tertiary amine, quite similar to 1 , however, having heptazine ligands instead of triazine ligands and is assigned with the formula N(C₆N₇Cl₂)₃ ( 3 ). Theoretical calculations were performed for the structures and the vibrational spectra of 1 and 3 . Theoretical calculations and a structure refinement based of X‐ray powder diffraction data yielded a plausible structural model for compound 3 .     

Polycondensation of benzyl chloride and its derivatives: A study of the reaction at different temperatures

The polycondensation reactions of benzyl chloride, α-chloroethylbenzene, and benzhydryl chloride in the presence of SnCl₄ or AlCl₃ as catalysts have been investigated in the temperature range between +80° and ?135°C. Polycondensations of benzyl chloride and α-chloroethylbenzene are quite similar in the reaction kinetics and are thought to occur by the same displacement mechanism. Polycondensation of benzhydryl chloride, however, seems to involve the formation of benzhydryl carbonium ions. At low temperatures linear polymers tend to be formed, in contrast with branched polymers produced at room temperature. Steric effects are found to play a major role in protecting polymers from branching at lower temperatures. Polybenzyl polymers are found to be less linear than poly(-α-methylbenzyl), even when prepared at ?135°C.     

Vinyl Chloride-Vinyl Bromide Copolymers

Abstract

Radical copolymerization kinetics of vinyl chloride (VC) and vinyl bromide (VB) lead to the following reactivity ratios r_VC=0.825 r_VB=1.05 Vinyl bromide acts as a chain transfer agent, more powerful than vinyl chloride, the transfer constant for VC radicals being 8.5 × 10^?3 at 40° C. Neither thermal nor ionic degrad-ation produce controlled distribution of short diene sequences in the copolymer. In the ionic process initiated with LiCl or LiBr in dimethylformamide solution, substitution of halogen atoms as well as acid elimination takes place.     

γ-Ray-induced polymerization of α-haloacrylic acids

The γ-ray induced polymerizations of α-chloroacrylic acid, mp 66°C, and α-bromo-acrylic acid, mp 72°C, were investigated in the temperature range from 35°C to 85°C. An analysis of polymerization kinetics was made, and results were similar to those reported in the literature for other vinyl monomers. On heating of the polymer obtained, elimination of hydrogen halide takes place, and intramolecular lactone formation is observed. The rate of lactone formation of poly(α-chloroacrylic acid) obtained in the solid-state polymerization was found to be higher than that in the liquid state, because a highly isotactic configuration of polymers, tends to be formed in the solid-state polymerization, and elimination of hydrogen chloride is facilitated with an isotactic 5₂ helix structure.     

Thin films of vanadium oxide grown on vanadium metal: oxidation conditions to produce V2O5 films for Li‐intercalation applications and characterisation by XPS,AFM, RBS/NRA

Thin films of vanadium oxide were grown on vanadium metal surfaces (i) in air at ambient conditions, (ii) in 5 mM H₂SO₄ (aq), pH 3, (iii) by thermal oxidation at low oxygen pressure (10^?5 mbar) at temperatures between 350 and 550 °C and (iv) at near‐atmospheric oxygen pressure (750 mbar) at 500 °C. The oxide films were investigated by atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS), X‐Ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). The lithium intercalation properties were studied by cyclic voltammetry (CV). The results show that the oxide films formed in air at room temperature (RT), in acidic aqueous solution, and at low oxygen pressure at elevated temperatures are composed of V₂O₃. In air and in aqueous solution at RT, the oxide films are ultra‐thin and hydroxylated. At 500 °C, nearly atmospheric oxygen pressure is required to form crystalline V₂O₅ films. The oxide films grown at pO₂ = 750 mbar for 5 min are about 260‐nm thick, and consist of a 115‐nm outer layer of crystalline V₂O₅. The inner oxide is mainly composed of VO₂. For all high temperature oxidations, the oxygen diffusion from the oxide film into the metal matrix was considerable. The oxygen saturation of the metal at 450 °C was found, by XPS, to be 27 at.% at the oxide/metal interface. The well‐crystallized V₂O₅ film, formed by oxidation for 5 min at 500 °C and 750 mbar O₂, was shown to have good lithium intercalation properties and is a promising candidate as electrode material in lithium batteries. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and Performance Evaluation of Temperature-controlled Viscous Acid

A temperature-controlled viscous acid thickener was obtained by copolymerizing acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, diallyl dimethyl ammonium chloride, and N-vinyl-2-pyrrolidinone, four monomers by aqueous solution polymerization, the mass ratio of the four monomers was 6: 2: 1: 1, the reaction temperature was 45°C and the reaction time was 6 h. The total mass concentration of the monomer was 25% and the oxidation-reduction system of ammonium persulphate and sodium hydrogen sulfite (mass ratio 1: 1) was used as the initiator, the amount was 0.9% of the total mass of the monomer, and the pH of the reaction solution was 6–8. Selecting glutaric dialdehyde and zirconium(IV) acetylacetonate as cross-linking agents, and compounding the synthesized quaternary copolymer after the mass ratio of the two reagents was 1: 1 to achieve acid temperature control viscous properties, were carried out. At 90°C, the quadripolymer and the cross-linking agent were mixed at a mass ratio of 5: 3, and then cross-linked at 60, 80, and 90°C, respectively, as time increased. The apparent viscosity increased sharply, and the apparent viscosity reached a maximum after 20, 15, and 10 min, and the maximum values were 680, 690, and 750 mPa s, respectively. The reaction of marble with thickening acid (20% hydrochloric acid + 1% thickener) and temperature-controlled viscous acid (20% hydrochloric acid + 1% thickener + 0.6 cross-linking agent) was performed at 90°C. The mass loss of marble was 58 and 42% of that of 20% pure hydrochloric acid, respectively. The performance evaluation results show that the temperature-controlled viscous acid has a good compatibility, and the retarding performance is greatly improved compared with the conventional thickened acid. It has good cross-linking and gel breaking performance under high temperature conditions and is suitable for high temperature formations with temperatures above 90°C. Between its excellent compatibility, it can be selected according to the corresponding formation conditions and construction purposes, and other types of acid working fluid or oilfield additives can be used together to achieve better construction results.

     

Electrodeposition of silver from dense gaseous solutions of silver nitrate in ammonia

Abstract

Silver was electrodeposited on platinum electrodes from solutions of AgNO₃ in NH₃ at temperatures from ?70°C. to 140°C. The solutions were 0.036 molar in AgNO₃ at ? 78°C. In the dense gaseous region, the concentrations of AgNO₃ and NH₃ were 0.018 and 22 moles/liter respectively.

The deposit was observed to become more and more crystalline in appearance as the temperature approached the critical temperature of NH₃(133°C). All electrodeposits at temperatures above 133°C were characterized by either dendritic or needle-like growths on sharp edges and corners. These were not observed at lower temperatures. Both three- and four-sided symmetries were observed, suggesting that the deposits were growing in the [111] and [100] directions, respectively.     

Synthesis of nanometric β-barium metaborate powder from different borate solutions by ultrasound-assisted precipitation

In this study, the synthesis of barium metaborate powder (BaB₂O₄) was carried out by ultrasound-assisted precipitation using different borate solutions. Different solutions such as borax (Na₂B₄O₇, BD), boric acid (H₃BO₃, BA), and sodium metaborate (NaBO₂, SMB) were used in the synthesis and an ultrasonic immersion horn probe was used as the major source of ultrasound. The effect of reaction temperature and time, pH, and crystallization time on the BaB₂O₄ yield (%) was investigated. The ultrasound-assisted synthesis up to 90 % yield could be achieved using a 0.2 M BD solution at 80 °C, reacting for 5 min at pH 13 followed by 2 h of crystallization. Following crystallization, the obtained powder was heated up to 140, 250, 650, and 750 °C for 2.5 h, and it was shown that β-BaB₂O₄ nanometric powders were obtained after the 750 °C heat treatment.     

Conversion of phosphogypsum to potassium sulfate

Summary Solubility of calcium sulfate in concentrated aqueous chloride solutions is of particular significance in chloride hydrometallurgy and various crystallization processes, such as the production of potassium sulfate from phosphogypsum and potassium chloride. This paper examines an example of the second type of application in which gypsum and potassium chloride are reacted to form K₂SO₄. The solubility of phosphogypsum in aqueous solutions of KCl, HCl, and mixtures of both has first been measured at various temperatures and concentrations. The parameters investigated are HCl concentration up to 6M, KCl concentration up to 180 g L^-1 and temperature from 25 to 80°C. In addition, the influence of co-existing chloride salts, such as (HCl+KCl), on the solubility of calcium sulfate is estimated from 25 to 80°C. The solubility increases obviously with the temperature increment as it does initially with acid concentration, reaching a maximum of about 3M HCl, 130 g L^-1 KCl and then drops. At the same time, the solubility of CaSO₄·2H₂O decreases with increasing KCl concentration.     

Nano-sized polycrystalline bismuth silicon oxide powder by sol–gel technique

Bismuth silicon oxide (Bi₁₂SiO₂₀, BSO) nano crystalline powder was prepared by sol–gel technique using bismuth nitrate and tetraethyl orthosilicate as starting materials. The prepared samples were sintered at various temperatures (750 °C maximum) and characteristic sillenite single cubic phase with crystallite size ~38 nm (calculated from room temperature powder XRD measurements) was realized at 750 °C sintering temperature. SEM analysis showed that the powder contains the nano-sized particles with almost spherical morphology. The observed frequencies in room temperature FTIR spectrum could be assigned to Bi–O, Si–O and Bi–O–Si bonds. The FWHM (full width at half maximum) of the diffraction peaks decreased while the intensity of FTIR absorption lines increased with the increase in the sintering temperature indicating better bond formation and crystallization. The thermograph of the samples recorded in the temperature range 50–1,000 °C showed almost no weight loss after ~575 °C further confirmed the conclusion arrived at from XRD and FTIR analysis. The samples sintered at 750 °C showed about 50% absorbance in 400–600 nm region which was consistent with the pale yellow color of the sample. Broad blue emission centered ~478 nm was observed when excited by 350 nm radiation from a Xe-lamp. The intensity of this broad emission band increased while its FWHM decreased with the increase in sintering temperature. Self-trapped excitons could be responsible for this emission.     

The influence of sodium chloride on the melting temperature of collagen crystalline region in parchments

In order to observe the influence of sodium chloride on the melting temperature of collagen crystalline region in three new parchments, samples were soaked in water (blanks) and NaCl solutions of different concentrations, then removed, dried in air and measured by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The melting temperature of crystalline region of collagen, T _m, was determined as the minimum of the endothermal peak in the range 200–250 °C and as the inflection point of the decrease of storage modulus, respectively. There was observed a decrease in melting temperature of the salt-treated parchments compared to the samples soaked in water, sometimes significant (~20 °C) at certain concentrations of NaCl. Simultaneous TG/DTG/DSC thermal analysis (STA) was also applied for the determination of the amount of sodium chloride in salt-treated parchments, by calculating the mass loss due to the vaporization of NaCl, which occurs above 800 °C. By plotting T _m determined by DSC and DMA versus the NaCl content of the samples, an apparent minimum is observed. Additional information regarding the structural features was also obtained through X-ray diffraction (XRD) and attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR). XRD data put in evidence the preservation of collagen crystalline region in all salt-treated samples, while FTIR measurements did not showed significant modification of collagen. By removing the sodium chloride from the salt-treated parchments through washing with water, there is a return of the melting temperatures to the values of blank samples, demonstrating the reversibility of this phenomenon.     

Hydration of medium reactive magnesium oxide using hydration agents

Water, magnesium acetate, magnesium chloride, acetic acid and hydrochloric acid were used as hydrating agents for an industrially obtained MgO sample. The influence of these different hydrating agents on the pH of the hydrating solution, degree of hydration to Mg(OH)₂, and product surface area was studied as a function of the temperature of hydration. When compared to the hydration in water, all hydrating agents improved the degree of hydration between 5 and 50% at all temperatures. MgCl₂ and a mixture of HCl and Mg(CH₃COO)₂ seemed to be the most effective hydrating agents below 60°C, while at temperatures above 60°C Mg(CH₃COO)₂ formed the largest percentage Mg(OH)₂. Mg(CH₃COO)₂ was the hydrating agent that showed the strongest temperature dependence. The mechanism of the hydration reaction seems to be dependent of the availability of Mg²⁺ ions and the increased formation of Mg(OH)₂ as temperature increases.     

Novel and Gram‐Scale Green Synthesis of Flutamide

Isobutyric acid in the presence of cyanuric chloride and N‐methylmorpholine was converted into active ester 3 at 0–5 °C, and it was subsequently treated with 3‐aminobenzotrifluoride 4 at 25 °C to furnish corresponding amide 5. This amide finally, on nitration, produced the desired product flutamide, 2‐methyl‐N‐[4‐nitro‐3‐(trifluoromethyl)phenyl]propionamide 6 in good yield. By‐product 2,4,6‐trihydroxy‐1,3,5‐triazine 7 was converted into the useful starting material cyanuric chloride 1 by refluxing with N,N‐diethylamine and POCl₃.     

Green synthesis of hydrotalcite from untreated magnesium oxide and aluminum hydroxide

The influence of reaction temperature and time on the hydrothermal dissolution-precipitation synthesis of hydrotalcite was investigated. Untreated MgO, Al(OH)₃ and NaHCO₃ were used. An industrially beneficial, economically favourable, environmentally friendly, zero effluent synthesis procedure was devised based on green chemistry principles, in which the salt-rich effluent typically produced was eliminated by regenerating the sodium bicarbonate in a full recycle process. It was found that the formation of hydromagnesite dominates at low temperatures independent of reaction time. With an increase in reaction time and temperature, hydromagnesite decomposes to form magnesite. At low temperatures, the formation of hydrotalcite is limited by the solubility of the Al(OH)₃. To achieve a hydrotalcite yield of 96%, a reaction temperature of 160°C for 5?h is required. A yield higher than 99% was achieved at 180°C and 5?h reaction time, producing an layered double hydroxide with high crystallinity and homogeneity.     

SYNTHESIS,BIOLOGICAL ACTIVITY,AND CHEMICAL RESISTANCE OF CARDO POLYSULFONATES BASED ON BISPHENOL-C AND ITS DERIVATIVES

ABSTRACT

Cardo polysulfonates (PS-1, PS-2, PS-4, PS-7, and PS-9) of 1,1′-bis(R,R′,4-hydroxy phenyl)cyclohexane (R=H, CH₃,Cl and Br; and R′?H, Cl and Br) with 4,4′-diphenyl ether disulfonyl chloride (DPESC) and 4,4′-diphenyl disulfonyl chloride (DPSC) have been synthesized by interfacial polycondensation of corresponding bisphenol (0.005 mol) and DPESC/DPSC (0.005 mol) by using water-1,2-dichloro-ethane/chloroform/dichloro methane (4:1 v/v) as an interphase, alkali (0.012–0.016 M) as an acid acceptor and cetyl trimethyl ammonium bromide (50 mg) as an emulsifier at 0°C for 3 hours. IR and NMR spectral data support the structures. The intrinsic viscosities of the said polymers are determined in different solvents at three different temperatures: 30°, 35°, and 40°C, and it is found that little solvent and temperature effect is observed on viscosities. All the polysulfonates possess good antibacterial activity against E. coli and S. aureus microbes and excellent resistance to hydrolytic attack against acids, alkalis and salt.     

In vacuo reduction of silver orthophosphate with graphite for high‐precision oxygen isotope analysis

The reduction of silver phosphate with graphite under vacuum conditions was studied at final reaction temperatures varying from 430 to 915°C to determine: (i) the CO₂ extraction yield, and (ii) the oxygen isotopic composition of CO₂. The CO₂ yield and oxygen isotopic composition were determined on a calibrated dual inlet and triple collector isotope ratio mass spectrometer. We observed the following three stages of the reduction process. (1) At temperatures below 590°C only CO₂ is formed, while silver orthophosphate decays to pyrophosphate. (2) At higher temperatures, 590–830°C, predominantly CO is formed from silver pyrophosphate which decays to metaphosphate; this CO was always converted into CO₂ by the glow discharge method. (3) At temperatures above 830°C the noticeable sublimation of silver orthophosphate occurs. This observation was accompanied by the oxygen isotope analysis of the obtained CO₂. The measured δ¹⁸O value varied from ?11.93‰ (at the lowest temperature) to ?20.32‰ (at the highest temperature). The optimum reduction temperature range was found to be 780–830°C. In this temperature range the oxygen isotopic composition of CO₂ is nearly constant and the reaction efficiency is relatively high. The determined difference between the δ¹⁸O value of oxygen in silver phosphate and that in CO₂ extracted from this phosphate is +0.70‰. Copyright © 2010 John Wiley & Sons, Ltd.     

Standard Partial Molar Volumes of Aqueous 2- and 3-Hydroxypropionic Acid from 100 to 325 °C: Functional Group Additivity in Isomers with Closely Spaced Polar Groups

Apparent molar volumes have been determined using a high-pressure vibrating-tube densimeter for aqueous solutions of 2- and 3-hydroxypropionic acid, at temperatures from 100?°C to 325?°C and pressures as high as 15 MPa. The results were corrected for acid ionization and extrapolated to infinite dilution to obtain the standard partial molar volumes, V ₂ ^o . The standard partial molar volumes of both isomers increase with temperature towards a positive discontinuity at the critical point, which is typical for almost all non-electrolytes. The temperature dependence of V ₂ ^o for the sodium salts of the acids is consistent with a negative discontinuity at the critical point, as displayed by all other aqueous electrolytes. Values of the apparent molar volumes of 2-hydroxypropionic acid are more positive than 3-hydroxypropionic acid by ～2 cm³?mol^?1, both in the neutral form and as the sodium carboxylate salt. This is the first demonstration at such high temperatures that functional group additivity in alkyl organic solutes with closely spaced polar groups is preserved to within such small differences. The onset of thermal decomposition prevented measurements at temperatures above 325?°C.     

Thermal Decompositions of Pure and Mixed Manganese Carbonate and Ammonium Molybdate Tetrahydrate

The thermal decompositions of pure and mixed manganese carbonate and ammonium molybdate tetrahydrate in molar ratios of 3:1, 1:1 and1:3 were studied by DTA and TG techniques. The prepared mixed solid samples were calcined in air at 500, 750 or 1000°C and then investigated by means of an XRD technique. The results revealed that manganese carbonate decomposed in the range 300–1000°C, within termediate formation of MnO₂, Mn₂O₃ andMn₃O₄. Ammonium molybdate tetrahydrate first lost its water of crystallization on heating, and then decomposed, yielding water and ammonia. At 340°C,MoO₃ was the final product, which melts at 790°C. The thermal treatment of the mixed solids at 500, 750 or 1000°C led to solid-solid interactions between the produced oxides, with the formation of manganese molybdate. At 1000°C, Mn₂O₃ and MoO₃ were detected, due to the mutual stabilization effect of these oxides at this temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

AES and LEED investigation of Al segregation and oxidation of the (100) face of Fe85Al15 single crystals

The surface segregation and oxidation behavior of Fe₈₅Al₁₅(100) were investigated by means of AES and LEED. Sputter cleaning of the surface causes preferential Al removal and leads to an Al depleted surface layer. The segregation of Al to the Fe₈₅Al₁₅(100) surface was studied in the temperature range from 300 to 800°C. At 375 to 400°C a weak c(2 × 2) LEED pattern is found. At temperatures in excess of 600°C thermodynamic equilibrium is approached very rapidly. At such temperatures Al segregation leads to a well-ordered (1 × 1) LEED structure with bright and sharp spots at a low background intensity. Oxidation at room temperature leads to disordered oxygen adsorption, whereas at 700°C a (6 × 6) superstructure is observed in addition to the matrix spots. This superstructure is attributed to the formation of a thin Al₂O₃ overlayer on the Fe₈₅Al₁₅(100) surface.