Absence Of Inert Gas Research Articles

A Reusable Palladium/Cationic 2,2′-Bipyridyl System-Catalyzed Double Mizoroki-Heck Reaction in Water

A reusable PdCl2(NH3)2/cationic 2,2′-bipyridyl system was used to catalyze the double Mizoroki-Heck reaction of aryl iodides with electron-deficient alkenes in water in the absence of inert gas, giving β,β-diarylated carbonyl derivatives in good to excellent yields. The formation of unsymmetrical β,β-diarylated alkenes were also studied by coupling aryl iodides with the corresponding aryl-substituted α,β-unsaturated carbonyl compounds. This water-soluble catalyst can be swiftly separated from the organic layer using simple extraction for the further reuse, and, thus, makes it an operationally-simple and environmentally-benign procedure.

Behavior of gas generation during the injection molding of poly(butylene terephthalate) in the presence and absence of inert gas

Behavior of gas generation during the injection molding of poly(butylene terephthalate) in the presence and absence of inert gas

Steady-State Diffusion Coefficients for Water in Nafion in the Absence of Inert Gas

Steady-state diffusion coefficients of water in Nafion were determined in the absence of inert gases at 25°C. A large range of water activity was investigated to determine average and differential diffusion coefficients. Flux decreased toward zero as the water activity gradient between water vapor and liquid water approached zero, indicating no Schroeder's paradox. The average diffusion coefficients varied between 1 × 10−6 and 5 × 10−6 cm2/s, with a minimum at 14 moles H2O/mol SO3−. Differential diffusion coefficients ranged between 4 × 10−7 and 2 × 10−5 cm2/s, with a minimum at 14 moles H2O/mol SO3−.

A Mild Liquid Reduction Route toward Uniform Blue-Emitting EuCl2 Nanoprisms and Nanorods

In this work, for the first time, uniform blue-emitting EuCl(2) nanoprisms and nanorods were synthesized from Eu(CCl(3)COO)(3)·2H(2)O [or Eu(CH(3)COO)(3)·H(2)O] by a novel mild liquid reduction route, using acetamidine hydrochloride (or picolinamidine hydrochloride) as the reductant in oleylamine. The synthetic reaction even can take place under an atmosphere in the absence of inert gas at around 300 °C. The EuCl(2) nanoprism dispersion in n-hexane showed an intense blue emission when excited by UV light.

Synthesis of Monodisperse Magnetite Nanocrystals via Partially Reduced Precipitation Method

Ferromagnetic Fe3O4 nanocrystals with sphere-like morphology have been successfully synthesized by a partial reduction-precipitated crystallization method using ferric chloride as single iron source, hydroxylammonium chloride (HONH3Cl) as reducing reagent, and ammonia as precipitating reagent. This synthesis is carried out in a reducing atmosphere in the absence of inert gas. The chemical composition and morphology of the sample were characterized by X-ray power diffraction (XRD), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM). The experiment results clearly show that the synthesized sample mainly consists of a large quantity of spherical Fe3O4 nanoparticles with a size of about 5–11 nm, and HONH3Cl plays important roles in the formation of the products. Besides, the magnetic property of the sample has been investigated using a vibrating sample magnetometer (VSM) and the magnetization saturation value is approximately 43.5 emu/g.

Preparation and properties of poly(WPSF‐co‐butyl acrylate) copolymer emulsion with ultrasonic radiation II. Monomer conversion rate and characterization

AbstractA stable emulsion of poly(WPSF‐co‐butyl acrylate) based on butyl acrylate, waste polystyrene foam was synthesized through emulsion polymerization using sodium dodecyl sulfate and octyl phenyl polyoxyethylene ether as surfactant, ammonium persulfate and sodium hydrogen bisulfate as mixed redox initiator, under ultrasound irradiation in the absence of inert gas. The effects of various copolymerization conditions on the monomer conversion were reported. The copolymers were characterized by means of IR, 1HNMR, and gel permeation chromatography. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthetic LiFePO 4/C without using inert gas

LiFePO 4/C was synthesized by high temperature solid-state method with cheap Fe 2O 3, LiH 2PO 4 and glucose as raw materials in absence of inert gas. The sample had ordered olivine-type structure other impurities characterized by the test of X-ray diffraction (XRD). The charge-discharge test showed the sample could demonstrate 120.5 mAh/g at 0.2C rate with good cyclic capability. The powder microelectrode cyclic voltammetry test indicated that the redox process of the sample had good reversibility.

Preparation and luminescent properties of SrS:Ce by addition of sulphur as a co-activator in SrSO4:Ce(SO4)2.4H2O by carbothermal reduction.

ABSTRACTCe activated SrS has been prepared from SrSO4:Ce(SO4)2.4H2O by ecologically acceptable carbothermal reduction in the absence of inert gas and hazardous H2S environment. The mixtures were fired at 900°C to find out the feasibility of the reduction reaction. In order to understand the compensator behavior we tried with sulfur and various fluxes viz., NH4Cl, NaCl. The materials synthesized were characterized by XRD, photoluminescence emission (PL) and excitation spectroscopy (PLE) and SEM. The characterization results showed the formation of SrS at 900°C with an increase in luminescence intensity after the addition of sulfur as a co-activator. The bright blue-green emission observed at 480nm and 540nm corresponds to energy bands originating from 2T2g (5d) to 2F7/2, 2F5/2(4f) of Ce3+ transitions. The excitation spectrum shows a fundamental absorption of SrS host crystal lattice in the lower wavelength region at 283 nm and Ce at 430 nm.

The spherical-droplet problem of evaporation and condensation in a vapour-gas mixture

The behaviour of a binary mixture of a vapour and an inert gas around the spherical condensed-phase droplet is studied analytically using kinetic theory. By the singular-perturbation method, the linearized Boltzmann equation of B–G–K type is first solved for problems with spherical symmetry under the diffusive boundary condition when the Knudsen number of the problem is small. The macroscopic equations and the appropriate boundary conditions in the form of the temperature and partial-pressure jumps on the interface between the droplet and the gas phase, which enable us to treat the problems at the level of ordinary fluid dynamics, are derived together with the Knudsen-layer structure formed near the interface. Then the velocity, temperature and pressure fields around the droplet are explicitly obtained, as well as the mass, heat and energy flows from it. The results obtained are capable of describing the transition from the diffusion-control to the kinetic-control mechanism in the mass-transfer process. The negative-temperature-gradient phenomenon, a common phenomenon for pure-vapour cases (absence of inert gas), is also possible, manifesting itself more easily as the kinetic-control mechanism becomes prevalent and the critical condition for its existence is given. The present analysis could be applied to other problems with spherical symmetry as well.

Pituitary-thyroid function of rats in hypobaric oxygen-inert gas environments.

Rats (200-260 g) were exposed in sealed, recycling chambers continuously for 2-30 days to gas mixtures designed to maintain the same alveolar PO2 in the presence or absence of inert gas. Mixtures with inert gas (N2, He, or Ne) were at ground level; those without inert gas (100 percent O2) were in an altitude chamber. The O2 categories were: I-100 percent O2 at 747 torr; II-74 percent O2 + 26 percent inert and 566 torr 100 percent O2; III-47 percent O2 + 53 percent inert and 381 torr 100 percent O2; IV-21 percent O2 + 79 percent inert and 197 torr 100 percent O2. One of the two room-air controls was "restricted-fed" to the level of the lowest intake group. Measurements included body, pituitary, and thyroid weight, food and water intake, plasma volume and hematocrit, pituitary and plasma TSH, and plasma PBI. Severe depression in all variables and over 50 percent mortality was seen in I by day 4. All variables were depressed in II, but there was no mortality to 20 days. Pituitary-thyroid function appeared to be particularly sensitive to depression by hyperoxia, with plasma TSH levels reduced between 42 and 60 percent in II and III. No effect was attributable to the inert gas, whether it was N2, He, or Ne, nor was any specific effect traceable to the presence or absence of inert gas.

Studies of the reactions of ethynyl radicals with hydrocarbons

It has been shown that ethynyl radicals may be satisfactorily generated by the photolysis, at 253.7 nm, of bromoacetylene in the presence of nitric oxide. Acetylene and butadiyne are primary products, being formed exclusively by the reactions C2H.+ C2HBr→C2H2+ C2Br., C2H.+ C2HBr→C4H2+ Br.. Nitric oxide decreases the rates of formation of both products, indicating the effective scavenging of ethynyl radicals by this compound. Addition of an inert gas (nitrogen or carbon dioxide) increases the ratio [C4H2]/[C2H2] from 3.5 (no inert gas) to 7 (total pressure 80 kPa (1 Pa = 1 N m-2)), the ratio thereafter remaining constant. The most obvious explanation for this behaviour is that, during photolysis, ethynyl radicals produced in the absence of inert gas have excess translational energy and, probably, enhanced reactivity. With increasing inert gas pressure, fewer ‘hot’ radicals react and the change in the ratio [C4H2]/[C2H2] reflects the change in selectivity of ‘thermalized’ ethynyl radicals. On account of this, investigations of the reactions of C2H.with added hydrocarbons were carried out with a standard 1:1:100 bromoacetylene-nitric oxide-nitrogen mixture. Results obtained with added alkanes (methane, ethane, 2,2 dimethylpropane) showed that ethynyl radicals abstract hydrogen atoms to form acetylene: C2H.+ RH→C2H2+ R., The relative importance of reactions (1) and (2) has been estimated and values fork1/k2of 0.016 ± 0.005, 0.54 ± 0.04 and 0 .91 ± 0.04 have been obtained for methane, and ethane 2,2-dimethylpropane respectively. The ratiok1/k2did not vary over the temperature range 298 to 478 K in the case of 2,2-dimethylpropane but with methane, values forE1—E2and A2/A1of 12.54 ± 1.27 kJ mol-1and 0.54 ± 0.25, respectively, were obtained. Studies of the reactions of ethynyl radicals with alkynes (acetylene, butadiyne and propyne) have shown that the radicals abstract hydrogen atoms (to form acetylene), displace hydrogen atoms (to form a di- or triyne) and, in the case of propyne, displace a methyl radical. For propyne, the relevant reactions are C2H.+ C3H4→C2H2+ C3H3., C2H.+ C3H4→C4H2+ CH3., C2H.+ C3H4→C5H4+ H., and Values of 25 ± 3, 5 ± 2, 9.9 ± 1 and 23 ± 3 at 298 K have been obtained fork7/k9,k4/k9,k8/k9andk2/k9respectively. In the presence of butadiyne, acetylene and hexatriyne are formed as primary products. Acetylene is formed by reactions (4) and (13), C2H.+C4H2→ C2H2+ C4H., whilst hexatriyne is formed by the displacement reaction (14) C2H.+ C4H2→C6H2+H.. Kinetic measurements have shown that at 298 Kk4/k14=0.6 ± 0.1 andk13/k14= 1.1 ± 0.2. Addition of acetylene-d2to bromoacetylene-nitrogen mixtures yields acetylene-d1and butadiyne-d1C2H.+ C2D2→ C2HD +C2D., C2H.+ C2D2→ C4HD + D.. The rate-constant ratiosk12/k11andk2/k12are 2 .8 ± 2.5 and 1.5 ± 0.3 respectively. This work thus indicates that ethynyl radical addition-elimination reactions, leading to polyalkynes, occur to a comparable extent to hydrogen-abstraction reactions in acetylene-containing systems. These results are shown to be of significance in regard to the formation and subsequent reactions of polyalkynes in both the pyrolysis and flames of acetylene and other hydrocarbons.

Survival of mice in absence of inert gas.

Summary1) Mice were maintained for 51 days in an atmosphere of oxygen at total pressure of 197 mm Hg. This provides a normal inspired O2 tension. CO2 and N2 pressures in the ambient atmosphere did not exceed 5 mm Hg for either gas. 2) Under these conditions animals usually did not encounter any difficulties. Several litters were born and in one case young were conceived, born and raised in virtual absence of inert gas. However, in several cases animals died within 48 hours after being subjected to this environment. Once past this period Only mechanical failure of the apparatus terminated these experiments. It is suggested that pulmonary atelectasis was responsible for these early deaths.