Ethoxide Solutions Research Articles

The bromine analog of sulfur mustard: Synthesis and reactivity studies

This paper presents a synthesis of the bromine analog of sulfur mustard, as well as a detailed description of its hydrolysis reactions under changing polarity conditions. Oxidation reactions of the bromine analog of sulfur mustard and its reactions with sodium ethoxide were also investigated. The oxidation kinetics of bis(2-bromoethyl) sulfide using selected oxidants, such as magnesium monoperoxyphthalate, ammonium persulfate, and hydrogen peroxide, was examined. There is a bromine analog of mustard gas which, instead of two chlorine atoms in the molecules of this compound, have bromine atoms. This compound has not been included in the Chemical Weapons Convention (CWC). This substance is poorly described in the literature. To better understand the chemical properties of a particular compound, it is often necessary to study the reaction of analog of a given substance under the same physicochemical conditions. It was found that the hydrolysis of bis(2-bromoethyl) sulfide proceeds from 6 to 16 times faster than in the case of sulfur mustard, depending on the water content in the reaction mixture. Also, the oxidation of the bromine derivative occurs three times (in the case of using (NH4)2S2O8) and ten times (in the case of H2O2) faster than the oxidation of sulfur mustard. The half-life of the decay of the bis(2-bromoethyl) sulfide during its reaction with sodium ethoxide solutions was 47.2 s. However, the same reaction of sodium ethoxide with mustard gas is about 18 times slower, and the half-life of sulfur mustard is about 14.7 min. The conclusions from this study may be helpful during the development of decontamination and neutralization techniques for sulfur mustard.

Microwave flash synthesis of iron and magnetite particles by disproportionation of ferrous alcoholic solutions

This paper reports the microwave-hydrothermal treatment of alcoholic solutions of ferrous chloride (FeCl2) and sodium ethoxide (EtONa) solutions with a microwave autoclave designed by the authors (the RAMO system). Depending on the initial concentrations, hematite (α-Fe2O3), spinel phase (Fe3 − xO4) or iron-magnetite (Fe0-Fe3O4) nanocomposites are obtained with a lower grain size compared to conventional composites. Indeed, X-ray diffraction (XRD) analysis reveals grain sizes close to 20 nm for magnetite and 60 nm for metallic iron. However, the amount of metal is smaller (close to 11%). Furthermore, these particles are inert in the ambient atmosphere. Consequently, the RAMO (French acronym of Reacteur Autoclave MicroOnde) system appears to provide an efficient source of energy in rapidly producing inert powders of iron, magnetite and iron-magnetite composites.

Carbon monoxide response of molybdenum oxide thin films deposited by different techniques

MoO 3 thin films have been deposited on alumina substrates by radio frequency (RF) sputtering from a metallic molybdenum target in a reactive atmosphere and by the sol–gel (SG) technique using molybdenum ethoxide solutions. The as-deposited RF films have been annealed at 500°C for 1 h, while the SG films have been annealed at temperature range between 400°C and 700°C for 1 h. The formation of a well-developed nanoparticle structure for the RF films with respect to the SG ones was suggested by scanning electron microscopy (SEM) characterisation. X-ray diffraction (XRD) has confirmed the formation of crystalline orthorhombic MoO 3 structures (JCPDS 5-508) for both the RF and SG films after annealing. The gas sensing properties towards CO have been examined. MoO 3-based gas sensors developed are capable of CO down to few ppm with a very fast response.

Effect of HCl catalyst in the formation of flat structures of Ta2O5 thin films by sol-gel technique

Ta 2 O 5 thin films have been prepared from tantalum ethoxide solutions [Ta(C2H5O)5] by sol-gel spin coating technique on Si (100) substrates and annealed at different temperatures ranging from 500 to 800 °C for 1 h. The physical, chemical and morphological characteristics of both fine powders and thin films have been characterized by bulk techniques like N2 adsorption and He porosimetry, thermogravimetry, differential thermal analysis and surface techniques like x-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), and x-ray photelectron spectroscopy (XPS). Additions of acid catalyst (HCl) and proper thermal treatment enable the formation of highly dense flat like films of Ta2O5, as observed by AFM observations. Films prepared from neutral precursor solutions show a micrometer-range porous network and a strongly marked rough polycrystalline surface structure. HCl catalyst resulted in a decrease of the crystallization temperature to 630 °C, with respect to a crystallization temperature of 732 °C found for the neutral prepared films. The evolution of dense structures upon HCl treatment has been confirmed by surface area and density measurements on the fine powders. XPS measurements have confirmed the formation of stoichiometric Ta2O5 for the HCl prepared films. The pH of the precursor solution as well as the annealing thermal treatment have resulted in the key process parameters for controlling the microstructural characteristics of the deposited films.

Microstructure and crystal structure development in porous titania coatings prepared from anhydrous titanium ethoxide solutions

Porous titania coatings were prepared by spin coating anhydrous titanium ethoxide–ethanol solutions in a controlled humidity atmosphere. Ti ethoxide reacted with atmospheric moisture during deposition, to form amorphous particles (approximately 200 nm), a dense layer or a combination of the two, depending on the processing conditions. Relatively humid atmospheres, low concentrations of Ti ethoxide in the coating solution and slow spinning rates favoured particle formation. These particulate coatings were typically composed of agglomerated particle clusters. Agglomeration could be prevented by adding hydroxypropyl cellulose to alkoxide solution to act as a steric stabilizer for newly formed particles. During thermal treatment, the coatings crystallized into the anatase phase and then transformed into the rutile structure at higher temperatures. The anatase–rutile transformation in porous coatings occurred over a range of 850–1150°C and strongly depended on microstructural features. More porous coatings with larger particle clusters transformed to rutile at lower temperatures. Tensile stress in the coating caused by constrained shrinkage inhibited the phase transformation. The substrate constraint slowed the transformation rate in coatings relative to free powder. Stress relief through rupture of particle cluster connections allowed transformation to occur at lower temperatures. © 1998 Kluwer Academic Publishers

Spin coating of titanium ethoxide solutions

Titanium oxide films are used in anti-reflection interference filters. These layers can be deposited by spinning titanium ethoxide (TEOTi) solutions. By thorough hydrolysis of the TEOTi precursor, optically acceptable coatings can be made even when cured at temperatures below 150°C.

Dip coating of titanium ethoxide solutions

Titania coatings are prepared by dip coating anhydrous titanium ethoxide solutions on glass substrates. Titanium ethoxide reacts with atmospheric water during deposition and drying to form coatings with a variety of microstructures. Transparent gel layers are prepared by coating in dry nitrogen and then exposing the coating to humid atmosphere or using slow withdrawal rates. Hydrated titania particles form in coatings deposited in atmospheres with relative humidity levels greater than ≈ 15%. These coatings are typically composed of agglomerates of small particles (≈0.3 μm); increases in substrate withdrawal rate and Ti ethoxide concentration in the solution bath lead to increases in thickness, particle size and extent of agglomeration. Particle aggregation is prevented by adding hydroxypropyl cellulose (HPC) to the coating solution before deposition.

Processing and Characterization of Porous TiO2 Coatings

Titania coatings were prepared by spin coating anhydrous titanium ethoxide solutions onto Si substrates. During deposition, Ti ethoxide in the solution layer reacted with atmospheric moisture to form precipitated particles. The resulting microstructures were composed of a network of particles and particle clusters. The induction time for precipitation, the particle diameter, and the size and packing of particle clusters were influenced by the Ti concentration in the sol and the spinning rate used for deposition. Individual particle sizes ranged from ∼150 to 250 nm. Smaller particles and more compact particle clusters were characteristic of coatings prepared from solutions with lower Ti concentrations and those prepared using faster spinning rates. Asdeposited coatings were amorphous and crystallized into the anatase phase at ∼400°C. Transformation to the rutile phase began at ∼850°C, and the transformation rate was influenced by the microstructure.

A SAXS study of the gelation process of silicon and titanium alkoxides

The gelation process of silicon ethoxide and titanium iso-propoxide solutions was studied as a function of water content and reaction time by small-angle X-ray scattering (SAXS). Approaching the gelation points, the SAXS intensities for titanium tetra-iso-propoxide solutions start to follow a power-law decay in the Porod region, except for a H 2O/Ti ratio greater than 4. For silicon ethoxide solutions, the fractal dimension, d f, measured for aggregated clusters increases continually with the H 2O/Si ratio and can be related to the spinnability of the solutions. For solutions of both silicon and titanium alkoxides, a solution of fractal dimension d f < 1.79 shows spinnability, whereas solutions having d f > 1.79 and no fractal structures do not show spinnability.

Preparation Of Copper And Copper-Barium-Yttrium Sols From Metal 2-(2-Ethoxyethoxy)Ethoxides and Conversion Of Copper-Barium-Yttrium Alkoxide Precursors to Ba2YCu3O7−δ.

ABSTRACTThe hydrolysis of copper 2–(2-ethoxyethoxy)ethoxide solutions and barium-yttrium copper 2–(2-ethoxyethoxy)ethoxide solutions were investigated. Copper sols with particle sizesof 3–10 nm have been prepared from THF solutions. Sols from barium-yttrium-copper alkoxides were also prepared in THF with particle sizes of 4–10 nm as determined by transmission electron microscopy (TEM) and 50–80 nm as determined by photon correlation. Compositional analysis showed that the sols had a similar composition to the parent solution. Choice of atmosphere and solvent system played an important role in the progress of the hydrolysis reaction. Powders obtained from barium-yttrium-copper solutions can be converted to Ba2YCu3O7−δ.

Catalytic Control of SiO2 Sol-Gel Kinetics - a Mechanistic Study of Bases

ABSTRACTThe aim of this research was to determine the relative effects of three different base catalysts (NaOH, NH4OH, and RbOH) on the rate of gelation of SiO2 from reactive silicon ethoxide solutions in alcohol (the sol/gel method). The time to gelation was determined using a reaction protocol which assured that condensation was the rate controlling step. NMR spectroscopy was used to verify that the nature of the reacting polymers remained similar as the base catalyst was varied. It was determined that under these conditions the condensation reactions avoid diffusional limitations. Furthermore, the base catalyst serves to modulate both the activation energy and also the Arrhenius preexponential factor. This leads to the proposal of a new condensation mechanism.

Meisenheimer adduct formation between 2,4-dinitrophenetole and ethanolic alkali ethoxide solutions: the course of the acidity function J E and thermodynamic solvent isotope effects

Spectrophotometric measurements of the equilibrium constant (Kapp) for formation of a Meisenheimer adduct from 2,4-dinitroanisole and ethanolic sodium and potassium ethoxide have been used to define an acidity function JE for alkoxide solutions in ethanol (analogous to the functions JM for methanol). Sodium and potassium ethoxide behave identically up to a concentration of ca. 0.3 mol dm–3; above this value solutions of sodium ethoxide are slightly less basic. The dependence of Kapp on base concentration is interpreted in terms of ion-pairing effects. The formation of a 1 : 2 adduct becomes significant at high base concentrations, and appears to involve cation-specific ion-pairing effects. The limiting value of log Kapp at low concentrations is -3.1. In EtOD solutions of the same alkoxide concentration, the equilibrium constant is greater than that in EtOH solutions by a factor of 2.5. This result and measurements in mixtures of EtOH and EtOD are consistent with the formulation of the ethoxide ion as an entity containing three hydrogen-bonded solvent molecules, and a deuterium fractionation factor of ca. 0.72–0.73 for the hydrogen-bonded positions.

Reactions of Di-n-alkylphosphine Oxides with Halocarboxylic Acids and Their Esters

The reactions of di-n-alkylphosphine oxides (1) with halocarboxylic acids (2) and their esters (3) were carried out in boiling sodium ethoxide and methoxide solutions, respectively. The products were identified by P%, NV, and IR and MS spectra. Di-n-hexylphosphine oxide (1b) was reacted with haloacetic and 3-halopropionic acids X- (CH2) n-CO2H, (2) (X=Cl, Br; n=1, 2) to give di-n-hexylphosphinic and 3- (di-n-hexylphosphinyl) propionic acids ((4b) and (5b)), respectively. The yield increased with increasing the concentration of sodium ethoxide. Reactions of (1) with methyl bromoacetate and 3-bromopropionate ((3a) and (3b)), followed by alkaline (potassium hydroxide) hydrolysis, gave di-n-alkylphosphinic and 3- (di-n-alkylphosphinyl) propionic acids ((4) and (5)), respectively. In the case of (3a), the optimum condition was (1) : (3a) : [NaOMe] =1 : 1 : 1 (mol/mol/mol), but the yield of (5) increased with increasing concentration of sodium methoxide in the reaction with (3b). The reaction of di-n-heptylphosphine oxide (1c) with ethyl 2-bromobutyrate (1 : 1 : 1) gave 93% of di-n-heptylphosphinic acid (4c), but a trace of (4c) was obtained with ethyl acetate. An intermediate ester, methyl 3- (di-n-hexylphosphinyl) propionate (6b), was isolated in the reaction of (1b) with (3b) (1 : 1 : 2.2, t=5h) without the hydrolysis, and was easily hydrolyzed by potassium hydroxide. For the formation of (4) which is a new oxidation reaction of (1), a mechanism involving a nucleophilic attack of the reactive species R2P (O) Na (7) on the carbonyl carbon of (2) (n=1) or (3a) to give an intermediate enol phosphate analog (9) was proposed and discussed. For the formation of (5), a possible mechanism involving a nucleophilic addition of (7) to the activated olefin produced by the ordinary alkoxide promoted 1, 2-elimination of hydrogen halide from (2) (n=2) or (3b) was proposed and discussed.

Concentration cells and Electrolysis of Sodium ethoxide solutions

Concentration cells and Electrolysis of Sodium ethoxide solutions

ナトリウムエトキシドの電解及びアルコール溶液中のイオンの活性に就いて

ナトリウムエトキシドの電解及びアルコール溶液中のイオンの活性に就いて

Concentration cells and electrolysis of sodium ethoxide solutions

Concentration cells and electrolysis of sodium ethoxide solutions