Specificity and Non-Specificity in the Sensitized CO2-Laser-Induced Reaction of Tetrachloroethene

2001 ◽  
Vol 66 (11) ◽  
pp. 1593-1602 ◽  
Author(s):  
Boyd L. Earl ◽  
Richard L. Titus
Keyword(s):  
Co2 Laser ◽  
Laser Initiation ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Thermal Initiation ◽  
Principal Product ◽  
Induced Reaction

Previous workers have investigated the reaction of tetrachloroethene using thermal initiation and CO2-laser initiation via sensitizing species. In both instances, the principal product was found to be hexachlorobenzene. One group reported evidence of laser specificity in this reaction, in that BCl3 acted as a sensitizer to produce hexachlorobenzene as the principal product, but SF6 and BBr3 did not. We have found that specificity is highly dependent on reaction conditions. We reproduced the previous results using similar experimental conditions, but under different conditions, we found that the specificity is lost, with all three sensitizers which we used (BCl3, SF6, and SiF4) sensitizing the reaction to produce mainly hexachlorobenzene. There were some differences among the sensitizers, as, for example, the fact that SF6 produced the most nearly pure hexachlorobenzene product.

Novel Products in the CO2-Laser Induced Reaction of Trichloroethylene

1995 ◽  
Vol 60 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Boyd L. Earl ◽  
Richard L. Titus
Keyword(s):  
Irradiation Time ◽  
Product Distribution ◽  
Incident Power ◽  
Cell Geometry ◽  
Reaction Conditions ◽  
Peak Areas ◽  
Induced Decomposition ◽  
Nmr Methods ◽  
Induced Reaction ◽  
Novel Products

Previous reports on the thermal or CO2-laser induced decomposition of trichloroethylene have identified only one condensible product, hexachlorobenzene (in addition to HCl and mono- and dichloroacetylene). We have found that trichloroethylene vapor exposed to cw irradiation on the P(24) line of the (001 - 100) band of the CO2 laser at incident power levels from 8 - 17 W produces numerous products, of which the 13 major ones have been identified using IR, GC/MS, GC/FTIR, and NMR methods. All of these products have 4, 6, or 8 carbons, are highly unsaturated, and are completely chlorinated or contain a single hydrogen. C4HCl5 and C6Cl6 isomers (three of each) account for S 55% to 85% of total products (based on peak areas in the total ion chromatograms in GC/MS runs), depending on reaction conditions. In addition to characterizing the products, we discuss the dependence of the product distribution on laser power, irradiation time, and cell geometry, and we outline a possible mechanism.

scholarly journals Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

2021 ◽  
Author(s):  
Timothy Aljoscha Frede ◽  
Marlene Dietz ◽  
Norbert Kockmann
Keyword(s):  
Design Of Experiments ◽  
Process Development ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Flow Calorimeter ◽  
Microscale Flow ◽  
Increased Sensitivity ◽  
Important Time ◽  
Optimal Reaction

AbstractFast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted. Graphical abstract A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.

The Use of Reverse Mirage Spectroscopy to Determine the Absorption Coefficient of Liquid Methanol at CO2 Laser Wavelengths

1989 ◽  
Vol 43 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Dane Bićanić ◽  
Siegfried Krüger ◽  
Paul Torfs ◽  
Bruno Bein ◽  
Frans Harren
Keyword(s):  
Absorption Coefficient ◽  
Co2 Laser ◽  
Probe Beam ◽  
Laser Emission ◽  
Wavelength Region ◽  
Experimental Setup ◽  
Absorption Coefficients ◽  
Experimental Conditions ◽  
Liquid Samples

An experimental setup for performance of reverse mirage spectroscopy at CO2 laser wavelengths on liquid samples having high values of absorption coefficients is described. One and the same liquid is used as both the absorbing and deflecting medium. The Rosencwaig-Gersho theory has been applied, and the choice of experimental conditions that would enable determination of absorption coefficient β from the magnitude of photothermal signals measured at two different probe beam distances (probing locations) is discussed. The usefulness of this technique (essentially not inhibited by the requirements imposed on the sample's thickness) is tested on methanol having absorption coefficients β close to 300 cm−1 in the wavelength region covered by CO2 laser emission.

scholarly journals Propane Pre-Reforming into Methane-Rich Gas over Ni Catalyst: Experiment and Kinetics Elucidation via Genetic Algorithm

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3393 ◽  
Author(s):  
Sergey I. Uskov ◽  
Dmitriy I. Potemkin ◽  
Leniza V. Enikeeva ◽  
Pavel V. Snytnikov ◽  
Irek M. Gubaydullin ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Molar Ratio ◽  
Ni Catalyst ◽  
Propane Conversion ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Chromium Catalyst ◽  
Nickel Chromium ◽  
Wide Range ◽  
The Given

Pre-reforming of propane was studied over an industrial nickel-chromium catalyst under pressures of 1 and 5 bar, at a low steam to carbon molar ratio of 1, in the temperature range of 220–380 °C and at flow rates of 4000 and 12,000 h−1. It was shown that propane conversion proceeded more efficiently at low pressure (1 atm) and temperatures above 350 °C. A genetic algorithm was applied to search for kinetic parameters better fitting experimental results in such a wide range of experimental conditions. Power law and Langmuir–Hinshelwood kinetics were considered. It was shown that only Langmuir–Hinshelwood type kinetics correctly described the experimental data and could be used to simulate the process of propane pre-reforming and predict propane conversion under the given reaction conditions. The significance of Langmuir–Hinshelwood kinetics increases under high pressure and temperatures below 350 °C.

Assessment of non-standard reaction conditions for asymmetric 1,3-dipolar organocatalytic cycloaddition of nitrone with α,β-unsaturated aldehydes

2015 ◽  
Vol 69 (5) ◽  
Author(s):  
Melinda Mojzesová ◽  
Mária Mečiarová ◽  
Ambroz Almássy ◽  
Roger Marti ◽  
Radovan Šebesta
Keyword(s):  
Ionic Liquids ◽  
Flow Reactor ◽  
Dipolar Cycloaddition ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Flow Process ◽  
Unsaturated Aldehydes ◽  
Solvent Free Conditions ◽  
Standard Reaction ◽  
Organocatalytic Reactions

AbstractNon-standard experimental conditions can often enhance organocatalytic reactions considerably. The current study explores the effectiveness of a range of non-standard reaction conditions for the asymmetric organocatalytic 1,3-dipolar cycloaddition of a nitrone with α,β-unsaturated aldehydes. The influence of ionic liquids, high-pressure conditions, ultrasound, microwave irradiation and ballmilling was tested as well as the flow process. Because of the low reactivity of the nitrone and unsaturated aldehydes in the 1,3-dipolar cycloaddition, cycloadducts were isolated in only moderate yields from the majority of experiments. However, high diastereo- and enantioselectivities were observed in ionic liquids under solvent-free conditions and in the flow reactor.

scholarly journals TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A mechanistic study

2001 ◽  
Vol 113 (4) ◽  
pp. 333-342
Author(s):  
Rajesh K. Vatsa ◽  
Sisir K. Sarkar ◽  
Jai P. Mittal
Keyword(s):  
Co2 Laser ◽  
Mechanistic Study ◽  
Tea Co2 Laser ◽  
Induced Reaction

Fixation of Chromium in Wood from Trivalent Chromium Salt Solutions

Holzforschung ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 465-473 ◽  
Author(s):  
F. C. Jorge ◽  
T. M. Santos ◽  
J. Pedrosa de Jesus ◽  
W.B. Banks
Keyword(s):  
Trivalent Chromium ◽  
Alcoholic Solution ◽  
Metallic Zinc ◽  
Wood Degradation ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Nitrate Addition ◽  
Solution Reaction ◽  
Sulphate Salts ◽  
Chromium Salt

Summary The aim of this study was to fix chromium chemically in wood from trivalent chromium solutions. Chromium(III) nitrate, chloride and sulphate salts were applied, both in aqueous and in methanolic solutions. To improve chromium fixation metallic zinc was used as a strong reductant to generate labile Cr(II) species from Cr(III), and base was added (NaOH for water and NaMeO for methanol). Aqueous solution reaction conditions were always acidic in spite of base addition, leading to unacceptable levels of wood degradation (e. g., weight loss), although relatively high chromium levels were attained in some cases. Methanolic solutions did not lead to wood degradation, and there was fixation of high levels of chromium. Although the addition of NaMeO seemed to improve chromium fixation, a chromium precipitate always formed, usually after a long reaction time (> 4h). Therefore the following experimental conditions for chromium fixation are suggested: alcoholic solution of Cr(III) chloride or nitrate, addition of metallic zinc, at reflux. To avoid using large amounts of zinc, Cr(III)-solutions can also be reduced electrochemically.

scholarly journals Frequency Dependent Kinetics of the CW CO2 Laser Induced Reaction of CF3CF2Cl

1987 ◽  
Vol 7 (5-6) ◽  
pp. 271-277
Author(s):  
R. N. Zitter ◽  
D. F. Koster ◽  
N. Siddiqua
Keyword(s):  
Activation Energy ◽  
Absorption Band ◽  
Co2 Laser ◽  
Laser Frequency ◽  
Kcal Mole ◽  
Band Center ◽  
Laser Frequencies ◽  
Cw Co2 Laser ◽  
Kinetics Of ◽  
Induced Reaction

Kinetics of the decomposition of CF3CF2Cl at 50 torr by a cw CO2 laser have been studied over a range of laser frequencies extending 36 cm−1 below an absorption band center at 980 cm−1. At constant translational temperature, the change in the rate constant with laser frequency is a factor of 100, comparable to the effect previously observed in CF2ClCF2Cl. Arrhenius plots show an activation energy of 86.2 kcal/mole, independent of frequency.

scholarly journals Double catalytic effect of (PhNH3)2CuCl4 in a novel, highly efficient synthesis of 2-oxo and thioxo-1,2,3,4-tetra-hydopyrimidines

2015 ◽  
Vol 80 (5) ◽  
pp. 595-604 ◽  
Author(s):  
Nenad Jankovic ◽  
Zorica Bugarcic ◽  
Svetlana Markovic
Keyword(s):  
Catalytic Effect ◽  
Biginelli Reaction ◽  
Aromatic Aldehydes ◽  
Homogeneous Catalyst ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Complex Salts ◽  
Key Steps ◽  
Work Up

An innovative route for the construction of 2-oxo and thioxo-1,2,3,4-tetrahydropyrimidines was delineated through a multicomponent reaction under Biginelli conditions, starting from different aromatic aldehydes, ?-ketoesters and urea or thiourea. Proper choice of copper complex (PhNH3)2CuCl4, as a novel homogeneous catalyst, enables facile, efficient, and inexpensive reaction under mild experimental conditions. Moreover, we present the first application of this complex salts in organic synthesis ever. The obtained products are of high purity, and can be easily isolated from the reaction mixture in good to excellent yields. Also, compared to the classical Biginelli reaction conditions, the present method has the advantages in higher yields and experimental and work-up simplicity. To illustrate the joint catalytic action of the Cu2+ and phenylammonium ions, two key steps of Biginelli reaction were examined using the M06 functional.

PYROLYSIS OF AROMATIC COMPOUNDS AS A GUIDE TO SYNTHETIC REACTIONS IN SEDIMENTS

1994 ◽  
Vol 34 (1) ◽  
pp. 231 ◽  
Author(s):  
J. W. Smith ◽  
S. C. George ◽  
B. D. Batts
Keyword(s):  
Aromatic Hydrocarbon ◽  
Aromatic Compounds ◽  
Crucial Role ◽  
High Concentration ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Synthetic Reactions ◽  
High Degree

The syntheses of methylaromatics by the reactions of phenanthrene, anthracene and pyrene with coals and CH4 at 220°C to 400°C is demonstrated. At temperatures not exceeding 350°C the experimental conditions may be thermally equated, in terms of R0 values, to those approximating the oil window. Therefore, the high degree of methylation achieved, the insensitivity of the methylation process to reaction conditions and the systematic and theoretically predictable increases with temperature in the ratio of the ß/α substituted methyl isomers of the parent aromatic hydrocarbon, provide support for significant geosynthetic processes in sediments. The high concentration of n-alkanes generated from the coal may play a crucial role in reactions.

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