Application en série benzofurannique d'un nouveau procédé de nitration par l'acide nitrique en présence de chlorure stannique

1983 ◽  
Vol 61 (10) ◽  
pp. 2287-2290 ◽  
Author(s):  
Jacques Einhorn ◽  
Pierre Demerseman ◽  
René Royer
Keyword(s):  
Nitric Acid ◽  
Stannic Chloride ◽  
Experimental Conditions

A new nitration technique, using nitric acid in the presence of stannic chloride in dichloromethane, has been extended to a series of benzofurans. The ease of performing the reaction as well as the diversity of products that can be obtained under various experimental conditions make it a worthwhile technique. [Journal translation]

Kinetics of Alumina Removal from a Calcined Kaolin with Nitric, Sulphuric and Hydrochloric Acids

Clay Minerals ◽  
1970 ◽  
Vol 8 (3) ◽  
pp. 337-345 ◽  
Author(s):  
S. F. Hulbert ◽  
D. E. Huff
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Kinetic Data ◽  
Acid Leaching ◽  
Normal Reaction ◽  
Reaction Equation ◽  
Experimental Conditions ◽  
Image Position ◽  
Calcined Kaolin ◽  
Kinetics Of

AbstractAn investigation of the acid-leaching of a calcined kaolin was made to compare the reaction kinetics of hydrochloric, nitric, and sulphuric acids. The acid concentrations used were 5·9 and 8·6 normal. Reaction temperatures used were 95°, 80° and 60° C.Particular attention was given to finding a reaction equation which would mathematically represent the kinetic data. A nucleation rate equation of the general form, was found to represent these data. Values of m varied from 1·10 to 1·55 depending on the experimental conditions.Under the conditions employed the rate of alumina leaching is fastest with hydrochloric acid, slower with sulphuric acid, and slowest with nitric acid. The rate controlling steps are proposed from the experimental evidence.

scholarly journals THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION

1955 ◽  
Vol 38 (5) ◽  
pp. 581-598 ◽  
Author(s):  
Margaret R. McDonald
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Radiation Effects ◽  
Reaction Yield ◽  
X Rays ◽  
Dilute Solutions ◽  
Experimental Conditions ◽  
Ph Range ◽  
Ph Curve

The proteolytic activity of dilute solutions of clystalline trypsin is destroyed by x-rays, the amount of inactivation being an exponential function of the radiation dose. The reaction yield increases steadily with increasing concentration of trypsin, varying, as the concentration of enzyme is increased from 1 to 300 µM, from 0.068 to 0.958 micromole of trypsin per liter inactivated per 1000 r with 0.005 N hydrochloric acid as the solvent, from 0.273 to 0.866 with 0.005 N sulfuric acid as the solvent, and from 0.343 to 0.844 with 0.005 N nitric acid as the solvent. When the reaction yields are plotted as a function of the initial concentration of trypsin, they fall on a curve given by the expression Y α XK, in which Y is the reaction yield, X is the concentration of trypsin, and K is a constant equal to 0.46, 0.20, and 0.16, respectively, with 0.005 N hydrochloric, sulfuric, and nitric acids as solvents. The differences between the reaction yields found with chloride and sulfate ions in I to 10 µM trypsin solutions are significant only in the pH range from 2 to 4. The amount of inactivation obtained with a given dose of x-rays depends on the pH of the solution being irradiated and the nature of the solvent. The reaction yield-pH curve is a symmetrical one, with minimum yields at about pH 7. Buffers such as acetate, citrate, borate and barbiturate, and other organic molecules such as ethanol and glucose, in concentrations as low as 20 µM, inhibit the inactivation of trypsin by x-radiation. Sigmoid inactivation-dose curves instead of exponential ones are obtained in the presence of ethanol. The reaction yields for the inactivation of trypsin solutions by x-rays are approximately 1.5 times greater when the irradiation is done at 26°C. than when it is done at 5°C., when 0.005 N hydrochloric acid is the solvent. The dependence on temperature is less when 0.005 N sulfuric acid is used, and is negligible with 0.005 N nitric acid. The difficulties involved in interpreting radiation effects in aqueous systems, and in comparing the results obtained under different experimental conditions, are discussed.

scholarly journals Separation of tungsten and rhenium on alumina

2004 ◽  
Vol 69 (8-9) ◽  
pp. 683-688 ◽  
Author(s):  
Jurij Vucina ◽  
Dagoljub Lukic ◽  
Milovan Stoiljkovic
Keyword(s):  
Nitric Acid ◽  
Sodium Chloride ◽  
Aqueous Phase ◽  
Aqueous Media ◽  
Distribution Coefficients ◽  
Experimental Conditions ◽  
Efficient Separation ◽  
Separation Factors ◽  
Ph Range

The conditions for the efficient separation of tungsten(VI) and rhenium (VII) on alumina were established. The distribution coefficients K d for tungstate and perrhenate anions, as well as the separation factors ?(? = KdWO42-/Kd ReO4-) were determined using hydrochloric or nitric acid as the aqueous media. Asolution of sodium chloride in the pH range 2?6 was also examined. Under all the tested experimental conditions, alumina is a much better adsorbent for tungsten than for rhenium. The obtained results indicated that the best separation of these two elements is achieved when 0.01? 0.1 mol dm-3HCl or 1.0mol dm-3 HNO3 are used as the aqueous media. If NaCl is used as the aqueous phase, the best separation is achieved with 0.20 mol dm-3 NaCl pH 4?6. Under these experimental conditions, the breakthrough and saturation capacities of alumina for tungsten at pH4 are 17 and 26 mg W/g Al2O3 respectively. With increasing pH, these values decrease. Thus, at pH 6 they are only 4 and 13 mg W/g Al2O3, respectively.

Corrosion behavior of martensitic/ferritic oxide dispersed strengthened steels in nitric media

2011 ◽  
Vol 1298 ◽  
Author(s):  
Benoit Gwinner ◽  
Martin Auroy ◽  
Dominique Mas ◽  
Audrey Saint-Jevin
Keyword(s):  
Nitric Acid ◽  
Corrosion Behavior ◽  
Acid Concentration ◽  
Chromium Content ◽  
Nitric Acid Concentration ◽  
Linear Sweep Voltammetry ◽  
Linear Sweep ◽  
Experimental Conditions ◽  
Electrochemical Tests ◽  
Corrosion Kinetics

ABSTRACTThe corrosion behavior of three martensitic/ferritic oxide dispersed strengthened (ODS) steels with different chromium contents (respectively 9, 14 and 18wt %) has been studied in hot and concentrated nitric acid. Immersion and electrochemical tests have been carried out in different experimental conditions (temperature and nitric acid concentration). In each case, the corrosion kinetics has been characterized by mass loss measurement of samples (immersion tests) and the electrochemical behavior by linear sweep voltammetry techniques. The dependency of the corrosion rate with the chromium content in the steel, the nitric acid concentration and the temperature, has been quantitatively established and qualitatively discussed.

Different Carbon Nanotube Content and Dispersant on the Preparation of Fe3O4 / CNTs

2014 ◽  
Vol 1052 ◽  
pp. 79-85
Author(s):  
Yuan Cheng ◽  
Kang Ning Sun ◽  
Ai Min Li
Keyword(s):  
Carbon Nanotubes ◽  
Magnetic Properties ◽  
Nitric Acid ◽  
Surface Coating ◽  
Optimal Parameters ◽  
Experimental Conditions ◽  
Tumor Hyperthermia ◽  
Multiple Groups ◽  
Co Precipitation ◽  
Different Content

This article mainly introduced the preparation and properties of the thermal seed composite. And multiple groups of experiments have been done, which controlled by different content of carbon nanotubes, different surfactants. The results showed that: Fe3O4/CNTs can be made through chemical co-precipitation. Using the same surfactant and under the same experimental conditions, the carbon nanotubes’ surface coating is best and most homogeneous, when the content of the carbon nanotubes is 12.5%. When the content of carbon nanotubes is 12.5% and the experimental conditions are same, choosing CTAB as the surfactant, rather than SDS, finally get the better performance of sample. So the optimal parameters for the experiment are that the content of CNTs is 12.5%, and the choice of surfactant is CTAB. At this time, the surface of carbon nanotubes coats uniformly and the magnetic properties meet the requirements of tumor hyperthermia. In addition, as the carbon nanotubes contain varying degrees of nanocarbon particles, graphite fragments, amorphous carbon and other impurities, Therefore, in this paper, the carbon nanotubes are carbon nanotubes which have been purified with concentrated nitric acid.

scholarly journals Optimization of Nitric Acid Leaching of Rare Earth Elements From Moroccan Natural Phosphate

2020 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Marouane Amine ◽  
Fatima Asafar ◽  
Latifa Bilali ◽  
Mehdi Nadifiyine
Keyword(s):  
Rare Earth ◽  
Nitric Acid ◽  
Rare Earth Elements ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Optimal Conditions ◽  
Liquid Ratio ◽  
Experimental Conditions ◽  
Nitric Acid Leaching ◽  
Solid Liquid

Phosphate is a very important natural resource in Morocco and one of the secondary resources of rare earth elements. Our study is particularly interested in Youssoufia phosphate, which contains 228.77 ppm of rare earth elements (ΣREEs). The purpose of our work is to study the influence of different parameters (acid concentration, solid/liquid ratio and temperature) in order to determine the optimal conditions for the leaching of rare earths. An experimental design (Doehlert matrix) has been drawn up to optimize the experimental conditions of the leaching. All tests were made with nitric acid at different concentrations varying between 1.5M and 4.5M with a solid/liquid ratio of 1/12 to 1/6; reaction temperature and duration are respectively 20°C to 80 °C and 60 min. The optimal conditions are obtained when using 69 °C as temperature, 4.1 M as acid concentration and 1/9 as solid/liquid ratio.

scholarly journals Homogeneous nucleation rates of nitric acid dihydrate (NAD) at simulated stratospheric conditions – Part II: Modelling

2006 ◽  
Vol 6 (2) ◽  
pp. 2119-2149 ◽  
Author(s):  
O. Möhler ◽  
H. Bunz ◽  
O. Stetzer
Keyword(s):  
Nitric Acid ◽  
Process Model ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Diffusion Activation Energy ◽  
Experimental Conditions ◽  
Microphysical Process ◽  
Aerosol Chamber ◽  
Diffusion Activation ◽  
Good Agreement

Abstract. Activation energies ΔGact for the nucleation of nitric acid dihydrate (NAD) in supercooled binary HNO3/H2O solution droplets were calculated from volume-based nucleation rate measurements using the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) aerosol chamber of Forschungszentrum Karlsruhe. The experimental conditions covered temperatures T between 192 K and 197 K, NAD saturation ratios SNAD between 7 and 10, and nitric acid molar fractions of the nucleating sub-micron sized droplets between 0.26 and 0.28. Based on classical nucleation theory, a new parameterisation ΔGact=A×(T lnSNAD)-2+B is fitted to our experimetnal data with A=2.5×106 kcal K2 mol-1 and B=11.2−0.1(T−192) kcal mol-1. A and B were chosen to also achieve good agreement with literature data of ΔGact. The parameter A implies a constant interfacial tension σsl=51 cal mol-1 cm-2 between the growing NAD germ and the supercooled solution. A slight temperature dependence of the diffusion activation energy is represented by the parameter B. Investigations with a detailed microphysical process model showed that literature formulations of volume-based (Salcedo et al., 2001) and surface-based (Tabazadeh et al., 2002) nucleation rates significantly overestimate NAD formation rates when applied to the conditions of our experiments.

Complexes of stannic chloride and alkyl phenols and the influence of these complexes and of free phenol on the cationic polymerization of isobutene

1970 ◽  
Vol 48 (8) ◽  
pp. 1251-1262 ◽  
Author(s):  
R. F. Bauer ◽  
R. T. LaFlair ◽  
K. E. Russell
Keyword(s):  
Equilibrium Constants ◽  
Monomer Concentration ◽  
Stannic Chloride ◽  
Substituted Phenols ◽  
Experimental Conditions ◽  
Free Phenol ◽  
Rate Of Polymerization ◽  
Alkyl Phenols ◽  
A Chain ◽  
Active Initiator

The polymerization of isobutene in ethyl chloride solution at −78.5 °C has been studied using stannic chloride as catalyst and alkyl substituted phenols as cocatalysts. In preliminary experiments, the nature and extent of the complexing between phenols and stannic chloride was examined and it was shown that σ-complexing occurs between the oxygen of the phenol and the stannic chloride. Equilibrium constants were determined over the temperature range 30 to −50 °C and were used, together with hydrogen bonding data, to estimate the concentrations of complex and free phenol in the polymerization mixtures at −78.5 °C. The active initiator in the polymerization is probably the σ-complex but the free phenol acts as a chain terminating agent. This explains the ability of the cocatalyst to decrease the rate of polymerization under some experimental conditions. For isobutene concentrations up to 3 M and at constant dielectric constant the rate of polymerization and the molecular weight are proportional to the monomer concentration. A mechanism is proposed to account for the main features of the experimental results.

Sign in / Sign up

Export Citation Format

Share Document