scholarly journals Nitrobenzene Hydrogenation to N-phenylhydroxylamine: a New Approach to the Selectivity

2017 ◽  
Vol 4 (1) ◽  
pp. 19 ◽  
Author(s):  
S.D. Kushch
Keyword(s):  
Chemical Species ◽  
Colloid Particle ◽  
Initial Reaction ◽  
Complex Catalyst ◽  
Hydrogen Electrode ◽  
Total Consumption ◽  
New Approach ◽  
Nitrobenzene Hydrogenation ◽  
Ec Mechanism ◽  
Aprotic Dipolar Solvent

A new approach to resolve the problem of selectivity with respect to N-phenylhydroxylamine in nitrobenzene hydrogenation is proposed. N-phenylhydroxylamine only is the final product of nitrobenzene electroreduction in aprotic media. In this case nitrobenzene reduction carries out by alternation of electrochemical (electron transfer) and chemical (species formed protonation) stages i.e. by so-called EC mechanism. Such mechanism realization in nitrobenzene hydrogenation is possible if i) a catalyst activates hydrogen as “hydrogen electrode” i.e. serves electrons source; ii) a reaction media contains limiting proton concentration. These limitations are discharged in the media of aprotic dipolar solvent, which solvated both positive and negative species. Really, in aprotic dipolar solvents over reduced platinum complexes or lowpercentage (≤1 wt.%) platinum, iridium or osmium catalyst nitrobenzene is hydrogenated with process discontinuance after nitrobenzene total consumption. Nitrobenzene hydrogenation yields N-phenylhydroxylamine as the main (the yield is 98%) product. As these low-percentage catalysts, complex catalyst in situ is heterogeneous i.e. it represents a platinum colloid (particle size ~ 40 nm) stabilized by aprotic dipolar solvent. So, process of nitrobenzene  hydrogenation, which is similar to nitrobenzene electoreduction, can is created. A kinetic scheme proposed is analyzed and kinetic equation for initial reaction rate, which is conformed to kinetic data, is obtained.

Deep Atomic Binding (DAB) Hypothesis: A New Approach of Fission Product Chemistry

2006 ◽  
Author(s):  
Abdul-Wali M. S. Ajlouni
Keyword(s):  
Positive Charge ◽  
Chemical Species ◽  
Fission Process ◽  
New Approach ◽  
New Born ◽  
The Media ◽  
Pass Through ◽  
Stable Atom ◽  
Former Ussr

Former studies assumed that, after fission process occurs, the highly ionized new born atoms (20–22 positive charge), ionize the media in which they pass through before becoming stable atoms in a manner similar to 4-MeV-particles. Via ordinary chemical reactions with the surroundings, each stable atom has a probability to form chemical compound. Since there are about 35 different elemental atoms created through fission processes, a large number of chemical species were suggested to be formed. But, these suggested chemical species were not found in the environment after actual releases of FP during accidents like TMI (USA, 1979), and Chernobyl (former USSR, 1986), also the models based on these suggested reactions and species could not interpret the behavior of these actual species. It is assumed here that the ionization states of the new born atoms and the long term high temperature were not dealt with in an appropriate way and they were the reasons of former models failure. Our new approach of DEEP ATOMIC BINDING (DAB) based on the following: 1. The new born atoms which are highly ionized, 10–12 electrons associated with each nucleus, having a large probability to create bonds between them to form molecules. These bonds are at the L, or M shells, and we call it DAB. 2. The molecules stay in the reactor at high temperatures for long periods, so they undergo many stages of composition and decomposition to form giant molecules. By applying DAB approach, field data from Chernobyl, TMI and nuclear detonations could be interpreted with a wide coincidence resulted.

The Potential Application of Metal Binding Hydro- and Silica-Gels in Low-Level Radioactive Waste Processing

2008 ◽  
Author(s):  
Tadashi Tokuhiro ◽  
Josh W. Carey ◽  
Massimo Bertino ◽  
Akira Tokuhiro
Keyword(s):  
Radioactive Waste ◽  
Metal Binding ◽  
Liquid Waste ◽  
Chemical Species ◽  
Silica Gels ◽  
Waste Processing ◽  
Specific Chemical ◽  
New Approach ◽  
Low Level ◽  
Low Level Radioactive Waste

Within the management of radioactive waste, we sought to consider a new approach radioactive hazardous waste processing in aqueous or similar (low-level waste; LLW) forms LLW and in fact, ‘contaminants of concern’ is often stored as diluted aqueous solutions of radioactive (or non) elements and contained in storage containers. One of the general problems associated with mixed liquid waste is the lack of an efficient, effective, and inexpensive means of processing (separating) its constituents. Two of the objectives in processing solid, radioactive laden liquid LLW are as follows: 1) to separate/extract the radioisotopes from the rest of the mixed constituents, and 2) to produce stable solidified forms encapsulating radioactive elements. Recent R&D in the physical chemistry of gel materials, have identified promising approach to simultaneously achieve the above objectives. That is, by utilizing and manipulating the physicochemical properties of various silica- and polymer-based gels at the nanoscale, we have demonstrated a process by which to specific chemical species are encapsulated.

IMPEDANCE SPECTROSCOPIC STUDY OF Ca1-xYxTi1-xCoxO3 CERAMICS BASED HUMIDITY SENSOR

2005 ◽  
Vol 19 (10) ◽  
pp. 1783-1791
Author(s):  
RAJESH KUMAR KATARE ◽  
LAKSHMAN PANDEY ◽  
O. P. THAKUR ◽  
OM PARKASH ◽  
DEVENDRA KUMAR
Keyword(s):  
Humidity Sensor ◽  
Operating Temperature ◽  
Chemical Species ◽  
Ceramic System ◽  
Sensitive Material ◽  
New Approach ◽  
Proposed Model ◽  
Wide Range ◽  
Response To Change

The results of an investigation of humidity sensors based on ceramic material are discussed. It is widely approved that the ceramics based humidity sensor is superior to the polymer one due to their better thermal stability over a variety of chemical species, wide range of operating temperature and rapid response to change of humidity. Properties of humidity sensor based on ceramic system Ca 1-x Y x Ti 1-x Co x O 3 are presented. The role of each part of the sensitive material in the electrical conduction process is determined based on measurements and calculated equivalent circuits. The proposed model describes the water absorption on grain and grain boundaries surfaces with very good fit to the experimental data. A new approach to the modeling of the impedance frequency dependence by means of an equivalent circuit yields very promising results for sensors.

scholarly journals QUESTIONING THE RELEVANCE OF SOLUTION pH CALCULATION

2020 ◽  
Vol 6 (2) ◽  
pp. 0147-0151
Author(s):  
André Fernando De Oliveira
Keyword(s):  
Chemical Species ◽  
Equilibrium Concentration ◽  
Strong Acid ◽  
Acid Base ◽  
Solution Ph ◽  
New Approach ◽  
Alternative Approach ◽  
Acid Base Equilibrium ◽  
Charge Parameter

A brief discussion on the unnecessary calculation of pH in solution was done, as the historical reasons for this need before the invention of commercial pH meter was widely diffused. An alternative approach for acid-base equilibrium evaluation was proposed, without approximation or need of application only for simple solutions. The central aspect for the new approach is the determination of equilibrium concentration of all chemical species in solution, including the strong acid or base concentration for adjusting of pH of solutions. Therefore, the proposed method allowed the calculation in a mixture, including several polyprotic systems. Two detailed examples were presented. The effective electrical charge parameter was formally defined.

Effect of support on activity of palladium catalysts in nitrobenzene hydrogenation

2014 ◽  
Vol 68 (5) ◽  
Author(s):  
Ľubomír Pikna ◽  
Mária Heželová ◽  
Silvia Demčáková ◽  
Miroslava Smrčová ◽  
Beatrice Plešingerová ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Palladium Catalysts ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Nitrobenzene Hydrogenation ◽  
Multi Walled Carbon Nanotubes ◽  
Effect Of Support ◽  
Adsorption Desorption ◽  
Walled Carbon Nanotubes

AbstractThe effect of two types of catalysts on the activity of the catalytic hydrogenation of nitrobenzene was studied. Catalysts were prepared by the surface deposition of palladium hydroxide with a simultaneous reduction with formaldehyde in a basic environment and were characterised by X-ray powder diffraction, transmission electron microscopy, adsorption-desorption, and catalytic tests — hydrogenation of nitrobenzene in methanol. The influence of the supports’ (activated carbon and a mixture of activated carbon and multi-walled carbon nanotubes) surface area is discussed. Despite having a size comparable (4–5 nm) to crystallites of metallic palladium, the catalyst prepared on a mixture of activated carbon and nanotubes (Pd/C/CNT) was significantly less active than the catalyst prepared on pure activated carbon (Pd/C); the rate of this reaction was approximately 30 % lower than the initial reaction rate. This feature could be attributed to the lower specific surface area of the Pd/C/CNT (531 m2 g−1) in comparison with the Pd/C (692 m2 g−1).

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

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