ARYLATION DES QUINONES PAR LES SELS DE DIAZONIUM: VIII. SUR LES 3-ARYL-1,2-NAPHTOQUINONES

1966 ◽  
Vol 44 (21) ◽  
pp. 2563-2565 ◽  
Author(s):  
Jacques Asselin ◽  
Paul Brassard ◽  
Philibert L'ecuyer
Keyword(s):  
Reaction Mechanism ◽  
Reaction Medium

The arylation of 1,2-naphthoquinone by benzenediazonium salts, in contrast to previously published results, gave only 3-aryl-1,2-naphthoquinones with poor to fair yields. The best reaction medium has been sought and the implications of the results with regard to the reaction mechanism are discussed.

Chlorination of 2,4,6-trichlorophenol in acidic aqueous medium

1985 ◽  
Vol 50 (8) ◽  
pp. 1842-1851 ◽  
Author(s):  
Petr Švec
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Medium ◽  
Hydrogen Chloride ◽  
Reaction Medium ◽  
Model Experiments ◽  
Sulfuric And Hydrochloric Acids

The course of chlorination of 2,4,6-trichlorophenol (I) in water and approximately 20% sulfuric and hydrochloric acids has been investigated. In all these media the reaction gives primarily 2,4,6,6-tetrachloro-2,4-cyclohexadienone (II) which is subsequently chlorinated under formation of polychlorinated alicyclic ketones or isomerized to give the more stable 2,4,6,6-tetrachloro-2,5-cyclohexadienone (III), the precursor of further arising chlorinated 1,4-benzoquinones. The ratio of the arising polychlorinated alicyclic ketones to chlorinated 1,4-benzoquinones is significantly influenced by concentration of hydrogen chloride in the reaction medium. On the basis of model experiments, the reaction mechanism of exhaustive chlorination of 2,4,6-trichlorophenol has been suggested.

scholarly journals The reaction mechanism of polyalcohol dehydration in hot pressurized water

2016 ◽  
Vol 18 (47) ◽  
pp. 32438-32447 ◽  
Author(s):  
Sergi Ruiz-Barragan ◽  
Jordi Ribas Ariño ◽  
Motoyuki Shiga
Keyword(s):  
High Temperature ◽  
Reaction Mechanism ◽  
Green Chemistry ◽  
Liquid Water ◽  
Reaction Medium ◽  
Pressurized Water ◽  
Promising Technology ◽  
Temperature Liquid

The use of high-temperature liquid water (HTW) as a reaction medium is a very promising technology in the field of green chemistry.

scholarly journals The reaction mechanism of the [2+3] cycloaddition between α-phenylnitroethene and (Z)-C,N-diphenylnitrone in the light of a B3LYP/6-31G(d) computational study

2013 ◽  
Vol 11 (3) ◽  
pp. 404-412 ◽  
Author(s):  
Radomir Jasiński ◽  
Maria Mikulska ◽  
Andrzej Barański
Keyword(s):  
Reaction Mechanism ◽  
Gas Phase ◽  
Computational Study ◽  
Reaction Medium ◽  
Reaction Pathways ◽  
Reactivity Indices ◽  
Polar Media ◽  
One Step ◽  
Step Mechanism

AbstractAbstract The analysis of reactivity indices suggests the polar nature of the [2+3] cycloaddition of a-phenylnitroethene to (Z)-C,N-diphenylnitrone. Similar conclusions can be drawn from the investigation of the reaction pathways using the B3LYP/6-31g(d) algorithm. This shows that the cycloaddition mechanism depends on the polarity of the reaction medium. A one-step mechanism is followed in the gas phase and toluene in all the theoretically possible pathways. In more polar media (nitromethane, water), a zwitterionic, two-step rather than a one-step mechanism occurs in the pathway leading to 3,4-trans-2,3,5-triphenyl-4-nitroisoxazolidine. Graphical abstract

Enantioselective Reduction Reactions Using Chiral Ionic Liquids: An Overview

2018 ◽  
Vol 15 (5) ◽  
pp. 578-586 ◽  
Author(s):  
Avtar Singh ◽  
Nirmaljeet Kaur ◽  
Harish Kumar Chopra
Keyword(s):  
Ionic Liquids ◽  
Reaction Mechanism ◽  
Reaction Medium ◽  
Reduction Reaction ◽  
Additional Benefit ◽  
Reduction Reactions ◽  
Chiral Ionic Liquids ◽  
Enantioselective Reduction ◽  
Insight Into

Background: Enantioselective reduction reactions play a key role to synthesize compounds of industrial importance. A number of metal and biocatalysts have been developed for their use in this reaction. Chiral ionic liquids (CILs) have been widely used as the reaction medium and the organocatalysts in enantioselective reduction reactions. Objective: This paper focuses on the systematic literature review about the use of chiral ionic liquids (CILs) in the enantioselective reduction reaction. The mechanistic aspects of these species are also taken into account. Conclusion: This review concludes that a number of chiral ionic liquids (CILs) have been successfully employed as the organocatalysts and the reaction medium in the enantioselective reduction reactions. The review also gives an insight into the role of these species in the reaction mechanism. For most of the reactions, chiral ionic liquids provide promising results in terms of yield and enantioselectivity. The recyclability of these chiral moieties from the reaction mixtures offers an additional benefit for the use of these species in asymmetric reactions.

scholarly journals A Kinetic Study of 2-Amino-4-(Methyl-Thio) Butanoic Acid By Quinaldinium Fluorochromate In Selected Hydrophilic Solvent Medium

2021 ◽  
Vol 11 (6) ◽  
pp. 30-35
Author(s):  
Elavarasan, A. ◽  
Dharmaraja J. ◽  
Raj V. ◽  
.Harikrishnan B ◽  
Vadivel S.
Keyword(s):  
Reaction Mechanism ◽  
Oxidation Kinetics ◽  
Sodium Perchlorate ◽  
Reaction Medium ◽  
Chemical Oxidation ◽  
Polymerization Reaction ◽  
Butanoic Acid ◽  
Solvent Medium ◽  
Hydrophilic Solvent ◽  
Activation Conditions

A Major role in oxidation kinetics is to determine the reaction mechanism that comprise chemical reaction. In the present paper we derived rate law for reaction mechanism and to recognized the order of reaction, give rate equation, calculate the rate constant. Identify the product of this oxidation reaction.The chemical oxidation of 2-Amino-4-methyl thio-butanoic acid by Quinaldinium Fluorochromate was studied in 50-50 (v/v) selected hydrophilic solvent medium at 308 Kelvin. The reaction is acid catalysed and exhibits first order dependence with respect to oxidant, substrate, and fractional order respect to H+ ion concentrations. Chemical oxidation kinetics is the study of the rate of chemical reaction.the factors Manganesh sulphate, Acrylonitrile, Sodium perchlorate that affect these rates (or) not, and draw of ln Kobs/T verses 1/T energy diagram to find the activation energy. Addition of sodium perchlorate slightly decreases the rate of reaction. However, Acrylonitrile is not induced by the polymerization reaction, showing that there is no free radical route. Added Mn2+ increases with slightly increase rate in the reaction medium. 2-Amino-4-(MethylThio)-Butanoic acid by Quinaldinium Fluorochromate has not been reported. Hence, the investigation of oxidation of 2-Amino-4-Methyl Thio-Butanoic acid by QNFC in selected hydrophilic solvent medium and the corresponding mechanistic aspects are discussed in this research paper. A systematic kinetic work carried out to explore the physical characterization of the reactance. The characterstic effects like Substrate, Oxidant, Perchloric acid, Solvent, Sodium perchlorate, Acrylonitrile, Manganes sulphate and Influence Temperature it clearly shows effect on that reaction path. The process was carried out at four different temperatures to determine the activation conditions. The measured kinetic findings ΔH# and ΔS# are derived from the value.

A contribution to the study of the catalytic action of clays on the polymerization of styrene: II. Reaction mechanism

Clay Minerals ◽  
1988 ◽  
Vol 23 (1) ◽  
pp. 35-43 ◽  
Author(s):  
D. Njopwouo ◽  
G. Roques ◽  
R. Wandji
Keyword(s):  
Reaction Mechanism ◽  
Thermal Effect ◽  
Reaction Mechanisms ◽  
Nmr Spectra ◽  
Reaction Medium ◽  
Clay Content ◽  
Thermal Polymerization ◽  
Radical Mechanism ◽  
Parallel Reaction ◽  
C Nmr

AbstractThe study of 13C NMR spectra of polystyrene thermally obtained on clays shows that thermal polymerization of styrene on these minerals proceeds by two parallel reaction mechanisms: the radical mechanism due to the thermal effect, and the cationic mechanism in which the initiatory cation H+ is provided by the clay. The latter mechanism, accelerated by increase in temperature, becomes more important as the clay content increases in the reaction medium. Otherwise, the thermal polymerization on clays is accompanied by the hydrogenation of some α carbons of the polystyrene molecule and the oxidation of certain aromatic carbons.

High-voltage cytochemistry for three-dimensional observation of nuclei and calculation of total numbers of nuclear pores in retinal Mueller glia

1990 ◽  
Vol 48 (3) ◽  
pp. 956-957
Author(s):  
H. Ishigooka ◽  
S. Ueno ◽  
L.M. Hjelmeland ◽  
M.B. Landers ◽  
K. Ogawa
Keyword(s):  
Nuclear Envelope ◽  
High Voltage ◽  
Three Dimensional ◽  
Reaction Medium ◽  
Nuclear Pores ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
G6pase Activity ◽  
Mueller Glia

Introduction: We have demonstrated that Glucose-6-phosphatase (G6Pase) activity is localized to the endoplasmic reticulum and nuclear envelope of Mueller glia in the normal and pathological guinea pig retina. Using a combination of this cytochemical technique and high voltage electron microscopy, the distribution of nuclear pores could be clearly observed on the nuclear envelope of Mueller glia because of their anatomical lack of reaction products. This technique was developed to study the three-dimensional structure of nuclei and to calculate total numbers of nuclear pores utilizing a computer graphic analysis system in the normal and pathological retina.Materials and methods: Normal and photocoagulated retina of pigmented adult guinea pigs were perfused with a cold mixture of 0.25% glutaraldehyde and 2% paraformaldehyde in 0.1M cacodylate buffer, and the enucleated globes were hemisected and immersed in the same fixative for 30 min. After sectioning and incubation in the reaction medium for the detection of G6Pase activity by the method of Wachstein-Meisel, the sections were postfixed, dehydrated and embedded in Spurr’s epoxy resin. Serial thick sections (1.0um) were prepared for the observation by a Hitachi high voltage electron microscope (H 1250-M) with an accelerating voltage of 1000 Kv. and pictures were analyzed and three-dimensionally reconstructed by TRI (RATOC Co., Ltd.).

Arylation of enelactams using TIPSOTf: reaction scope and mechanistic insight

2021 ◽  
Author(s):  
Tomasz J. Idzik ◽  
Zofia M. Myk ◽  
Łukasz Struk ◽  
Magdalena Perużyńska ◽  
Gabriela Maciejewska ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Multinuclear Nmr ◽  
Mechanistic Insight ◽  
Nmr Study ◽  
Wide Range

Triisopropylsilyltrifluoromethanesulfonate can be effectively used for the arylation of a wide range of enelactams. The multinuclear NMR study provided deep insights into the reaction mechanism.

Reaction of Acetaldehyde with Human Platelets

1992 ◽  
Vol 67 (01) ◽  
pp. 126-130 ◽  
Author(s):  
Olivier Spertini ◽  
Jacques Hauert ◽  
Fedor Bachmann
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Reaction Medium ◽  
Human Platelets ◽  
Membrane Glycoproteins ◽  
Neutral Ph

SummaryPlatelet function defects observed in chronic alcoholics are not wholly explained by the inhibitory action of ethanol on platelet aggregation; they are not completely reproduced either in vivo by short-term ethanol perfusion into volunteers or in vitro by the addition of ethanol to platelet-rich plasma. As acetaldehyde (AcH) binds to many proteins and impairs cellular activities, we investigated the effect of this early degradation product of ethanol on platelets. AcH formed adducts with human platelets at neutral pH at 37° C which were stable to extensive washing, trichloracetic acid hydrolysis and heating at 100° C, and were not reduced by sodium borohydride. The amount of platelet adducts formed was a function of the incubation time and of the concentration of AcH in the reaction medium. At low AcH concentrations (<0.2 mM), platelet bound AcH was directly proportional to the concentration of AcH in the reaction medium. At higher concentrations (≥0.2 mM), AcH uptake by platelets tended to reach a plateau. The amount of adducts was also proportional to the number of exposures of platelets to pulses of 20 pM AcH.AcH adducts formation severely impaired platelet aggregation and shape change induced by ADP, collagen and thrombin. A positive correlation was established between platelet-bound AcH and inhibition of aggregation.SDS-PAGE analysis of AcH adducts at neutral pH demonstrated the binding of [14C]acetaldehyde to many platelet proteins. AcH adduct formation with membrane glycoproteins, cytoskeleton and enzymes might interfere with several steps of platelet activation and impair platelet aggregation.This in vitro study shows that AcH has a major inhibitory action on platelet aggregation and may account for the prolonged ex vivo inhibition of aggregation observed in chronic alcoholics even in the absence of alcoholemia.

Sign in / Sign up

Export Citation Format

Share Document