scholarly journals Mechanism of Chlorination Process: From Propanoic Acid to α-Chloropropanoic Acid and Byproducts Using Propanoic Anhydride as Catalyst

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Da Xue ◽  
Yuna Li ◽  
Jisheng Liu ◽  
Chuan Gao ◽  
Jianwei Xue ◽  
...  
Keyword(s):  
Activation Energy ◽  
Glass Tube ◽  
Dft Method ◽  
Radical Mechanism ◽  
Propanoic Acid ◽  
Ionic Mechanism ◽  
Chlorination Process ◽  
Tube Reactor ◽  
Concentrated Sulfuric Acid ◽  
Reactor Operating

This article reports on findings regarding the mechanism of chlorination process. In this experiment, propanoic acid was chlorinated to α-chloropropanoic acid in a lab-scale glass tube reactor operating at 130°C. Propanoic anhydride and concentrated sulfuric acid were, respectively, used as the catalyst and the promoter. This experiment adopted the DFT method to calculate the activation energy of routes for the synthesis α-chloropropanoic acid, β-chloropropanoic acid, α,α-dichloropropanoic acid, and α,β-dichloropropanoic acid. The results showed that the main route of α-chloropropanoic acid was formed through an ionic mechanism when propanoic anhydride was used as the catalytic agent. Activation energy of 1-propen-1-ol,1-chloro, which was formed from 1-prop-anol,1-chloro-, was the highest in the process of ionic mechanism. In addition, α,α-dichloropropanoic acid was formed via a consecutive ionic chlorination path from α-chloropropanoic acid. β-Chloropropanoic acid was produced from propanoic acid through a chlorination radical mechanism. α,β-Dichloropropanoic acid was formed via a consecutive radical chlorination path.

scholarly journals Theoretical DFT study of Cannizzaro reaction mechanism: A mini perspective

2020 ◽  
Vol 11 (2) ◽  
pp. 139-144
Author(s):  
Mohammad Suhail ◽  
Sofi Danish Mukhtar ◽  
Imran Ali ◽  
Ariba Ansari ◽  
Saiyam Arora
Keyword(s):  
Molecular Structure ◽  
Free Radical ◽  
Density Functional ◽  
Heterogeneous Medium ◽  
Homogeneous Medium ◽  
Radical Mechanism ◽  
Ionic Mechanism ◽  
Free Radical Mechanism ◽  
Actual Mechanism ◽  
Cannizzaro Reaction

In regards to the Cannizzaro reaction and its peculiar mechanism, some researchers have presented a free radical mechanism for the Cannizzaro reaction, while others have found that it is feasible through an ionic mechanism, but the actual mechanism has not been finalized yet. The researchers have given the proof of both the mechanisms through their papers published. Actually, Cannizzaro reaction may occur through both mechanisms depending on both molecular structure and different conditions which are yet to be explained. Recently published papers describe that free radical mechanism occurs only in a heterogeneous medium, while an ionic mechanism occurs in a homogeneous medium. We revealed no explanation of the molecular structure-based reason, responsible for a radical or an ionic mechanism. The present paper reviews not only homogeneous/heterogeneous medium conditions but also molecular structure-based facts, which may be responsible for the Cannizzaro reaction to occur through the radical or ionic mechanism, and that may be acceptable to the scientific society. Besides, Density Functional Theory study using Gaussian software was also involved in the explanation of the molecular structure, responsible for one of the two mechanisms. Also, the present paper specifies all points related to future perspectives on which additional studies are required to understand the actual mechanism with a definite molecular structure in the different reaction media.

Gas Phase Adduct Reactions in MOCVD Growth of GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
A. Thon ◽  
T.F. Kuech
Keyword(s):  
Activation Energy ◽  
Gas Phase ◽  
Decomposition Temperature ◽  
Adduct Formation ◽  
Gas Phase Reactions ◽  
Flow Tube ◽  
Exponential Factor ◽  
First Order ◽  
Mocvd Growth ◽  
Tube Reactor

ABSTRACTGas phase reactions between trimethylgallium (TMG) and ammonia were studied at high temperatures, characteristic to MOCVD of GaN reactors, by means of insitu mass spectroscopy in a flow tube reactor. It is shown, that a very fast adduct formation followed by elimination of methane occurs. The decomposition of TMG and the adduct - derived compounds are both first order and have similar apparent activation energy. The pre-exponential factor of the adduct decomposition is smaller, and hence is responsible for the higher full decomposition temperature of the adduct relative to that of TMG.

Nanofibers - A Simple and Practical Way Forward for Air Pollution Abatement

2013 ◽  
Vol 756 ◽  
pp. 225-230 ◽  
Author(s):  
Naeem Shahzad ◽  
Qiao Chen
Keyword(s):  
Uv Light ◽  
Pollution Abatement ◽  
Glass Tube ◽  
Tube Reactor ◽  
Electrospinning Method ◽  
Before And After ◽  
Enhanced Adsorption ◽  
Air Pollution Abatement ◽  
Very High

Nanofibers have proved to be highly efficient due to their enhanced adsorption capacity, because of high pores and very high surfacearea. Pure and Sulphur doped TiO2nanofibers were synthesized using electrospinning method in this study to evaluate their destruction potential for H2S gas, using photocatalysis. Experiments were carried out under laboratory conditions using capillary glass tube reactor under UV light. 97% destruction was achieved using pure TiO2nanofibers while the destruction percentage decreased when S-doped TiO2nanofibers were replaced with the pure ones. Characterization of the nanofibers before and after running the experiments was carried out using XRD, SEM and EDX techniques. The destruction of H2S gas was measured in ppm using BioGas Analyser fitted with GPA1.8 Gas pod for H2S detection.

THE OXIDATION OF HYDRAZOBENZENE BY AMMONIUM PERSULPHATE IN ACETONITRILE–WATER SOLUTION

1956 ◽  
Vol 34 (9) ◽  
pp. 1154-1162 ◽  
Author(s):  
B. J. P. Whalley ◽  
H. G. V. Evans ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Water Solution ◽  
Order Rate Constant ◽  
Second Order ◽  
Radical Mechanism ◽  
Square Root ◽  
Ammonium Persulphate ◽  
Initial Concentration ◽  
Free Radical Mechanism ◽  
Considerable Range

In a given experiment, second order kinetics were displayed during the greater part of the reaction over a considerable range of initial concentrations of reactants. In general, the second order behavior was maintained to greater extent of reaction when hydrazobenzene was in excess. The calculated second order rate constant, k, decreased with increase in initial hydrazobenzene concentration and increased with increase in initial concentration of ammonium persulphate. For different equimolar concentrations of reactants, k was virtually independent of initial concentrations. The value of k was proportional to the square root of the ratio of the initial concentrations of persulphate and hydrazobenzene. The activation energy of the over-all reaction was 16 kcal. per mole. A free radical mechanism appears to account reasonably well for the major experimental observations.

KINETICS AND MECHANISMS OF THE PYROLYSIS OF n-BUTANE: PART I. THE UNINHIBITED DECOMPOSITION

1963 ◽  
Vol 41 (4) ◽  
pp. 838-847 ◽  
Author(s):  
N. H. Sagert ◽  
K. J. Laidler
Keyword(s):  
Activation Energy ◽  
Surface Effect ◽  
Frequency Factor ◽  
Radical Mechanism ◽  
Free Radical Mechanism ◽  
Surface Catalysis ◽  
Initiation Reaction ◽  
Pressure Changes ◽  
Ethyl Radicals ◽  
Kinetics Of

The kinetics of the pyrolysis of n-butane have been studied at temperatures from 520° to 590 °C, and at pressures from 30 to 600 mm Hg; the rate was followed from pressure changes and by gas chromatography. The reaction was accurately of the three-halves order; the activation energy was found to be 59.9 kcal mole−1, and the frequency factor 3.24 × 1015 cc1/2 mole−1/2 sec−1. The reaction is sensitive to surface; packing the vessel and 'conditioning' it usually led to a decrease in rate and an increase in activation energy. The reaction is concluded to be largely homogeneous, and to occur almost entirely by a free-radical mechanism; the initiation reaction is considered to be the dissociation of a butane molecule into two ethyl radicals, in its first-order region, and termination is believed to be the second-order combination of ethyl radicals. The mechanism proposed is shown to account satisfactorily for the observed behavior. The surface effect is attributed to a certain amount of initiation by abstraction, by a surface atom, of a hydrogen atom from butane, and to surface catalysis of the recombination of ethyl radicals.

THE PYROLYSIS OF DIALLYL (1,5-HEXADIENE)

1960 ◽  
Vol 38 (6) ◽  
pp. 827-834 ◽  
Author(s):  
D. J. Ruzicka ◽  
W. A. Bryce
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Radical Mechanism ◽  
Static System ◽  
Kcal Mole ◽  
Temperature Range ◽  
Gaseous Products ◽  
Mechanism Of Decomposition ◽  
Liquid Products

The mechanism of decomposition of diallyl has been studied in a static system in the temperature range 460–520 °C. The principal gaseous products (room temperature) were propylene, methane, ethylene, and 1-butene, and the liquid products were cyclopentene, cyclopentadiene, 1-hexene, and benzene. The over-all activation energy of decomposition was 31.3 ± 1.0 kcal/mole for an A factor of 107 sec−1. A mechanism of decomposition based on hydrogen abstraction by allyl and the addition of allyl to olefinic double bonds is proposed. Some decomposition by a non-radical mechanism may also occur.

Exogeneous factors are not necessary in attachment, spreading and polarization of hela cells

1978 ◽  
Vol 36 (2) ◽  
pp. 310-311
Author(s):  
W. Liebrich
Keyword(s):  
Hela Cells ◽  
Calf Serum ◽  
Glass Tube ◽  
Serum Free Medium ◽  
Nacl Solution ◽  
Free Medium ◽  
Minimum Essential Medium ◽  
Serum Free ◽  
All Solutions ◽  
Glass Support

HeLa cells were grown for 2-3 days in EAGLE'S minimum essential medium with 10% calf serum (S-MEM; Seromed, München) and then incubated for 24 hours in serum free medium (MEM). After detaching the cells with a solution of 0. 14 % EDTA and 0. 07 % trypsin (Difco, 1 : 250) they were suspended in various solutions (S-MEM = control, MEM, buffered salt solutions with or without Me++ions, 0. 9 % NaCl solution) and allowed to settle on glass tube slips (Leighton-tubes). After 5, 10, 15, 20, 25, 30, 1 45, 60 minutes 2, 3, 4, 5 hours cells were prepared for scanning electron microscopy as described by Paweletz and Schroeter. The preparations were examined in a Jeol SEM (JSM-U3) at 25 KV without tilting.The suspended spherical HeLa cells are able to adhere to the glass support in all solutions. The rate of attachment, however, is faster in solutions without serum than in the control. The latter is in agreement with the findings of other authors.

Electron sources: Past, present, and future

1993 ◽  
Vol 51 ◽  
pp. 764-765
Author(s):  
David C Joy
Keyword(s):  
Glass Tube ◽  
Source Size ◽  
Electron Gun ◽  
Operating Parameters ◽  
Operational Parameters ◽  
Electron Sources ◽  
Difficult Decision ◽  
Probe Size ◽  
Wide Range ◽  
Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

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