Étude expérimentale et modélisation des réactions d'oxydation du n-pentane et du cyclopentane

1997 ◽  
Vol 75 (5) ◽  
pp. 575-584 ◽  
Author(s):  
V. Simon ◽  
Y. Simon ◽  
G. Scacchi ◽  
F. Baronnet
Keyword(s):  
Reaction Mechanisms ◽  
Relative Concentration ◽  
Reaction Medium ◽  
Oxidation Mechanism ◽  
Reaction Vessel ◽  
Combustion Mechanism ◽  
Spark Ignition Engines ◽  
Research Octane Number ◽  
Automotive Emissions

The reduction of automotive emissions and the reformulation of gasoline composition require a better understanding of the combustion mechanism, in particular aiming at the determination of the influential reactions which are responsible for the onset of knock in spark ignition engines. We have studied the oxidation mechanism of two hydrocarbons of different research octane number: n-pentane (62) and cyclopentane (100). This work follows a previous study on the oxidation of n-heptane and isooctane. The experimental study was performed at 873 K in a jet-stirred flow reaction vessel. The reaction mechanisms of n-pentane and cyclopentane were analysed on a purely kinetic basis, derived from our experimental results, and were finally modelled by using a programme of simulation of reaction mechanisms. The different behaviour of these two hydrocarbons with respect to autoignition phenomena is mainly dependent on the relative concentration of resonance-stabilized radicals in the reaction medium. Keywords: oxidation reaction, n-pentane, cyclopentane, modelling, autoignition.

Article

1999 ◽  
Vol 77 (7) ◽  
pp. 1177-1190 ◽  
Author(s):  
S Taconnet ◽  
Y Simon ◽  
G Scacchi ◽  
F Baronnet
Keyword(s):  
Experimental Study ◽  
Reaction Mechanisms ◽  
Reaction Medium ◽  
Spark Ignition ◽  
Reaction Vessel ◽  
Spark Ignition Engines ◽  
Flow Reaction ◽  
Oxidation Mechanisms

The different behaviour of hydrocarbons with respect to autoignition phenomena is, at present, not yet fully explained. We have therefore investigated the oxidation of two alkanes that have different octane numbers: neopentane (85.5) and isopentane (92.3), to obtain a better understanding of their reaction mechanisms, in particular, those reactions that are responsible for the onset of knock in spark ignition engines. The experimental study was performed at 873 K in a jet-stirred flow reaction vessel. The oxidation mechanisms were simplified by using the CHEMKIN programme of simulation of reaction mechanisms. These mechanisms were compared to those accounting for the oxidation of n-pentane, cyclopentane, n-heptane, and isooctane that we have previously studied. This comparison shows that the different behaviour of these hydrocarbons can be explained, at least in part, by the presence, in the reaction medium, of resonance-stabilized radicals.Key words: oxidation, neopentane, isopentane, autoignition, modelling.

Determination of Complex Reaction Mechanisms

2006 ◽  
Author(s):  
John Ross ◽  
Igor Schreiber ◽  
Marcel O. Vlad
Keyword(s):  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Reaction Pathway ◽  
Chemical Species ◽  
Rate Coefficients ◽  
Chemical System ◽  
Evolutionary Development ◽  
Complex Reaction ◽  
Oscillatory Reactions

In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.

Infrared Quantitative Analysis of Mixtures Containing Isopropenyl Stearate, Stearic Acid, Stearic Anhydride, and Mixed Stearic—Acetic Anhydride

1972 ◽  
Vol 26 (1) ◽  
pp. 96-99 ◽  
Author(s):  
Mary Jo Calhoun ◽  
Edward S. DellaMonica
Keyword(s):  
Acetic Anhydride ◽  
Stearic Acid ◽  
Relative Concentration ◽  
Ternary Systems ◽  
Spectral Interference ◽  
Complex Mixtures ◽  
Ratio Method ◽  
Baseline Method ◽  
Binary And Ternary Systems

A method for the determination of individual components of complex mixtures is presented. The technique used is based on ir-absorbance measurements for stearic acid at 1700 and at 935 cm−1 when the concentration range exceeds 0.50% wt/vol; for isopropenyl stearate at 1145 and at 865 cm−1; for stearic anhydride at 1030 cm−1 and mixed stearic-acetic anhydride at 1000 cm−1. The baseline method was used in all absorbance measurements. Absorbance-concentration relationships obeyed Beer's law from 0 to 2.0% wt/vol for most compounds; the exception being stearic acid (at 1700 cm−1), where linearity was limited to a maximum 0.50% wt/vol. Due to spectral interference between the two anhydrides at low concentration ratios, an empirical percent transmission ratio method was used to estimate the relative concentration of each. Binary and ternary systems were studied and the standard deviations of the differences between theoretical and calculated values indicate that this method is reliable.

Determination of heterogeneous reaction mechanisms: A key milestone in dust explosion modelling

2021 ◽  
pp. 104589
Author(s):  
Matteo Pietraccini ◽  
Eloise Delon ◽  
Audrey Santandrea ◽  
Stéphanie Pacault ◽  
Pierre-Alexandre Glaude ◽  
...  
Keyword(s):  
Reaction Mechanisms ◽  
Heterogeneous Reaction ◽  
Dust Explosion

Electrochemical and Infrared Spectroscopic Quantitative Determination of the Platinum-Catalyzed Ethylene Glycol Oxidation Mechanism at CO Adsorption Potentials

Langmuir ◽  
1996 ◽  
Vol 12 (10) ◽  
pp. 2594-2601 ◽  
Author(s):  
Bonnie Wieland ◽  
J. Patrick Lancaster ◽  
Cherokee S. Hoaglund ◽  
Paul Holota ◽  
Wade J. Tornquist
Keyword(s):  
Ethylene Glycol ◽  
Quantitative Determination ◽  
Co Adsorption ◽  
Oxidation Mechanism ◽  
Infrared Spectroscopic ◽  
Ethylene Glycol Oxidation

Spectrophotometric Determination of Chlorpromazine Hydrochloride Using 4-Nitroanilline by Oxidative Coupling Reaction

2019 ◽  
Vol 16 (1(Suppl.)) ◽  
pp. 0194
Author(s):  
Al-rashidy Et al.
Keyword(s):  
Oxidative Coupling ◽  
Analytical Data ◽  
Reaction Medium ◽  
Coupling Reaction ◽  
Suggested Method ◽  
Sensitivity Index ◽  
Chlorpromazine Hydrochloride ◽  
Oxidative Coupling Reaction ◽  
Relative Standard

A simple, rapid spectrophotometric method has been established for the determination of chlorpromazine hydrochloride (CPZ) in its pure form and in a tablet formulations. The  suggested  method  is  based  on  the  oxidative coupling  reaction  with4-nitroainlline using KIO3 in acidic solution to produce a violet colored product with maximum absorption at λ=526 nm.The  analytical data  obtained  throughout  this  study  could  be  summarid  as  follows:  1ml of 1M HCl (pH=2.2), 1 ml  of  4-nitroanilline (1x10-2M), and 1.5ml  of (1x10-2)KIO3 per 25 ml reaction medium. The order of additions, coupling reaction time, and temperature in addition to the type of solvent were studied. The Beer′s law is obeyed over the concentration range of(5–40) µg ml-1, but the detection limit and quantification limit are 0.34 besides 1.03 µg ml-1 respectively. The correlation coefficient (r) for the calibration graph was found to be 0.9980, molar absorptivity of 10. 25 × 103 L.mol -1.cm-1, and Sandell′s sensitivity index of 0.03467 µg.cm-2. The precision and accuracy of the method were tested by calculating the percentage of relative standard deviation (RSD%) (<1.831%) and the average recovery percent (99.22%) average error percent Erel%(0.558). Direct and standard addition procedures were applied to both standards and specimens of pharmaceutical and the results indicate that the suggested method was successfully applied for the determination of CPZ.

Computations by Means of Macroscopic Chemical Kinetics

2006 ◽  
Author(s):  
John Ross ◽  
Igor Schreiber ◽  
Marcel O. Vlad
Keyword(s):  
Chemical Kinetics ◽  
Reaction Mechanisms ◽  
Parallel Machines ◽  
Electronic Device ◽  
Chemical Mechanism ◽  
Chemical Systems ◽  
Universal Turing Machine ◽  
Sequential Machines ◽  
Logic Functions

The topic of this chapter may seem like a digression from methods and approaches to reaction mechanisms, but it is not; it is an introduction to it. We worked on both topics for some time and there is a basic connection. Think of an electronic device and ask: how are the logic functions of this device determined? Electronic inputs (voltages and currents) are applied and outputs are measured. A truth table is constructed and from this table the logic functions of the device, and at times some of its components, may be inferred. The device is not subjected to the approach toward a chemical mechanism described in the previous chapter, of taking the device apart and testing its simplest components. (That may have to be done sometimes but is to be avoided if possible.) Can such an approach be applicable to chemical systems? We show this to be the case by discussing the implementation of logic and computational devices, both sequential machines such as a universal Turing machine (hand computers, laptops) and parallel machines, by means of macroscopic kinetics; by giving a brief comparison with neural networks; by showing the presence of such devices in chemical and biochemical reaction systems; and by presenting some confirming experiments. The next step is clear: if macroscopic chemical kinetics can carry out these electronic functions, then there are likely to be new approaches possible for the determination of complex reaction mechanisms, analogs of such determinations for electronic components. The discussion in the remainder of this chapter is devoted to illustrations of these topics; it can be skipped, except the last paragraph, without loss of continuity with chapter 5 and beyond. A neuron is either on or off depending on the signals it has received. A chemical neuron is a similar device.

Automated Immunochemical Method for Determination of Urinary Protein of Plasma Origin

1975 ◽  
Vol 21 (10) ◽  
pp. 1465-1468 ◽  
Author(s):  
Lawrence M Killingsworth ◽  
Carol E Britain ◽  
Linda L Woodard
Keyword(s):  
Polyethylene Glycol ◽  
Reaction Time ◽  
Human Plasma ◽  
Continuous Flow ◽  
Rapid Determination ◽  
Reaction Medium ◽  
Urinary Proteins ◽  
Immunochemical Method ◽  
Antigen Antibody

Abstract An automated continuous-flow procedure has been developed for the rapid determination of urinary proteins of plasma origin. Antiserum to whole human plasma was used as the reagent, and the antigen—antibody reactions were quantitated by nephelometry. By adding polyethylene glycol (mol wt 6000-7500) to the reaction medium, reaction time was decreased to &lt;3 min; no sample blanks were required; and samples were analyzed at a rate of 70 per hour. Recovery studies yielded an average of 98.5% of the added protein. In-run replicate precision (CV) of the method was 1.45%; day-to-day precision was 2.58%.

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