The Reaction of N,4-Dinitroso-N-Methylaniline and Polymers

1976 ◽  
Vol 49 (4) ◽  
pp. 1019-1030 ◽  
Author(s):  
E. Morita
Keyword(s):  
Free Radical ◽  
Elevated Temperature ◽  
Hydrogen Abstraction ◽  
Labile Hydrogen ◽  
Dilute Solution ◽  
Nitroso Group ◽  
Reaction Conditions ◽  
First Order ◽  
Pendent Group ◽  
Pseudo First Order

Abstract Both nitroso groups participate in the reaction of N,4-dinitroso-N-methyl-aniline (DNMA) with various polymers, and the pathways of the reaction are influenced by the reaction conditions. In dilute solution the rate of the reaction is proportional to the amount of unsaturation present and is pseudo-first order with respect to DNMA at elevated temperature with or without polymers present. The iV-nitroso group undergoes thermal fission liberating nitroxyl and N-methyl-p-nitrosoaniline free radicals. The presence of hydrocarbons with labile hydrogen accelerates the hydrogen abstraction by the amine free radical to form N-methyl-p-nitrosoaniline and a hydrocarbon free radical, which may combine with another amine free radical to form a hydrocarbon with pendent N-substituted-N-methyl-p-nitrosoanilme group. The 4-nitroso group of DNMA adds to the double bond, leading to the formation of an adduct with N-methyl-N-nitroso-p-phenylenediamine pendent group. Depending on the reaction conditions, the 4-nitroso groups may form azoxy compounds or may be oxidized to nitro groups. The bifunctionality of DNMA leads to the formation of crosslinked polymers or to chemical promotion of carbon black reinforcement with N, N′-disubstituted-N-methyl-p-phenylenediamine type crosslinks.

FIBRINOPEPTIDE B RELEASE FROM NORMAL FIBRINOGEN AND FIBRINOGEN LONDON I IN THE PRESENCE OF INHIBITORS OF FIBRIN POLYMERIZATION

1987 ◽  
Author(s):  
W Ruf ◽  
A Bender ◽  
K T Preissner ◽  
D A Lane ◽  
G Müller-Berghaus
Keyword(s):  
Initial Phase ◽  
Slow Rate ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
Reaction Conditions ◽  
Fibrin Polymerization ◽  
First Order ◽  
Molar Excess ◽  
Pseudo First Order ◽  
Fibrinogen Molecule

The fibrinopeptides A and B (FPA and FPB) are cleaved from the fibrinogen molecule with different rates. In the initial phase of the thrombin-fibrinogen reaction, FPB is released with a slow rate, which is enhanced upon polymerization of desA-fi-brin monomers. The aim of the present study was to further characterize the mechanism leading to the enhanced rate of FPB release during polymerization. For this purpose, the release of FPB from normal fibrinogen and from fibrinogen London I, which exhibits a polymerization defect located in the D-domain, was studied in the presence and absence of the fibrinolytic fragment D1 (D1) and of the synthetic tetrapeptide Gly-Pro-Arg-Pro (GPRP). Steady state parameters for fibrinopeptide release were determined under pseudo-first order reaction conditions. In the initial phase of the thrombin-fibrinogen reaction, the release of FPA was unchanged in the presence of D1. Furthermore, the release of FPA from fibrinogen London I did not reveal any difference in comparison to normal fibrinogen. GPRP prevented not only fibrin polymerization, but also the enhanced rate of FPB release. On the contrary, the rate of FPB release in the presence of a 16- and 32-fold molar excess of over fibrinogen did not differ from a reaction mixture with no added D1. Si-miliar to the inhibited rate of FPB release in the presence of GPRP, the release of FPB from fibrinogen London I occurred with a slow rate, which was not enhanced by the addition of a 16-fold molar excess of D1. Since the release neither from normal fibrinogen nor from ribrinogen London I was affected by D1, it was concluded that the D-E contact formed by D1 with an E-domain of a desA-fibrin molecule does not enhance the release of FPB. While GPRP keeps fibrin in monomeric form by inhibiting the polymerization sites in the D-domains, D1 does not prevent the formation of fibrin oligomers. Therefore, acceleration of FPB release is caused by a conformational change, which is induced by binding of reciprocal polymerization sites to an E-as well as a D-domain of the same desA-fibrin molecule.

scholarly journals Kinetic Evidence for Near Irreversible Nonionic Micellar Entrapment ofN-(2′-Methoxyphenyl)phthalimide (1) under the Typical Alkaline Reaction Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
M. Niyaz Khan ◽  
Yoke-Leng Sim ◽  
Azhar Ariffin
Keyword(s):  
Kinetic Analysis ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Total Concentration ◽  
Reaction Conditions ◽  
First Order ◽  
Order Rate ◽  
Alkaline Reaction ◽  
Pseudo First Order ◽  
Hydrolysis Of

The values of pseudo-first-order rate constants (kobs) for alkaline hydrolysis of1, obtained at 1.0 mM NaOH and withinCmEnT(total concentration ofCmEn) range of 3.0–5.0 mM forC12E23and 10–20 mM forC18E20, fail to obey pseudophase micellar (PM) model. The values of the fraction of near irreversibleCmEnmicellar trapped1molecules (FIT1) vary in the range ~0–0.75 forC12E23and ~0–0.83 forC18E20under such conditions. The values ofFIT1become 1.0 at ≥10 mMC12E23and 50 mMC18E20. Kinetic analysis of the observed data at ≥10 mMC12E23shows near irreversible micellar entrapment of1molecules under such conditions.

HYDROGEN ABSTRACTION REACTIONS OF DIPHENYLPICRYLHYDRAZYL

1958 ◽  
Vol 36 (1) ◽  
pp. 159-166 ◽  
Author(s):  
A. G. Brook ◽  
R. J. Anderson ◽  
J. Tissot Van Patot
Keyword(s):  
Nitrous Oxide ◽  
Free Radical ◽  
Hydrogen Abstraction ◽  
Reaction Conditions ◽  
Stable Free Radical ◽  
Variable Stoichiometry ◽  
Formation Of Complexes

The stable free radical diphenylpicrylhydrazyl (DPP•) has been found to react quantitatively with ammonia and hydrazine forming nitrogen and diphenylpicrylhydrazine, and less cleanly with hydroxylamine forming diphenylpicrylhydrazine and nitrous oxide. The reactions of DPP• with a variety of amines are not clean, in part owing to the formation of complexes of the amines with the reaction product diphenylpicrylhydrazine. Preliminary investigations of the reactions of DPP• with mercaptans have shown that these otherwise clean reactions have a variable stoichiometry, dependent on the concentration and other reaction conditions.

scholarly journals A Highly Efficient Ag Nanoparticle-Immobilized Alginate-g-Polyacrylonitrile Hybrid Photocatalyst for the Degradation of Nitrophenols

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3049
Author(s):  
Imran Hasan ◽  
Charu Shekhar ◽  
Walaa Alharbi ◽  
Maymonah Abu Khanjer ◽  
Rais Ahmad Khan ◽  
...  
Keyword(s):  
Irradiation Time ◽  
Analytical Techniques ◽  
Order Rate Constant ◽  
Order Kinetic ◽  
Ag Nps ◽  
Reaction Conditions ◽  
First Order ◽  
Order Kinetic Model ◽  
Pseudo First Order

Herein, we report PAN-g-Alg@Ag-based nanocatalysts synthesis via in situ oxidative free-radical polymerization of acrylonitrile (AN) using Alg@Ag nanoparticles (Alg@Ag NPs). Various analytical techniques, including FTIR, XRD, SEM, TEM, UV–Vis, and DSC, were employed to determine bonding interactions and chemical characteristics of the nanocatalyst. The optimized response surface methodology coupled central composite design (RSM–CCD) reaction conditions were a 35-min irradiation time in a 70-mg L−1 2,4-dinitrophenol (DNP) solution at pH of 4.68. Here, DNP degradation was 99.46% at a desirability of 1.00. The pseudo-first-order rate constant (K1) values were 0.047, 0.050, 0.054, 0.056, 0.059, and 0.064 min−1 with associated half-life (t1/2) values of 14.74, 13.86, 12.84, 12.38, 11.74, 10.82, and 10.04 min that corresponded to DNP concentrations of 10, 20, 30, 40, 50, 60, and 70 mg L−1, respectively, in the presence of PAN-g-Alg@Ag (0.03 g). The results indicate that the reaction followed the pseudo-first-order kinetic model with an R2 value of 0.99. The combined absorption properties of PAN and Alg@Ag NPs on copolymerization on the surface contributed more charge density to surface plasmon resonance (SPR) in a way to degrade more and more molecules of DNP together with preventing the recombination of electron and hole pairs within the photocatalytic process.

scholarly journals Exploring the scope of DBU-promoted amidations of 7-methoxycarbonylpterin

2020 ◽  
Vol 16 ◽  
pp. 509-514 ◽  
Author(s):  
Anna R Bockman ◽  
Jeffrey M Pruet
Keyword(s):  
Reaction Kinetics ◽  
Structural Features ◽  
Product Formation ◽  
Reaction Conditions ◽  
First Order ◽  
First Order Kinetics ◽  
Synthetic Utility ◽  
Pseudo First Order ◽  
Pteridine Derivatives

The synthetic utility of pterins is often hampered by the notorious insolubility of this heterocycle, slowing the development of medicinally relevant pteridine derivatives. Reactions which expedite the development of new pterins are thus of great importance. Through a dual role of diazabicycloundecene (DBU), 7-carboxymethylpterin is converted to the soluble DBU salt, with additional DBU promoting an ester-to-amide transformation. We have explored this reaction to assess its scope and identify structural features in the amines which significantly affect success, monitored the reaction kinetics using a pseudo-first order kinetics model, and further adapted the reaction conditions to allow for product formation in as little as 5 min, with yields often >80%.

scholarly journals Permanganatic oxidation of neomycine sulphate salt in basic media: a kinetic study

2019 ◽  
Vol 9 (1) ◽  
pp. 159-164
Author(s):  
Narayan V. Lawale ◽  
Bhagwan Singh Dobhal ◽  
Sandip Singh Gaur ◽  
Rajendra Pardeshi
Keyword(s):  
Kinetic Study ◽  
Order Reaction ◽  
First Order Reaction ◽  
Pseudo First Order Reaction ◽  
Reaction Conditions ◽  
First Order ◽  
Alkaline Permanganate ◽  
Different Temperatures ◽  
Alkaline Conditions ◽  
Pseudo First Order

Permanganatic oxidation of Neomycine sulphate salt has been studied at different temperatures using spectrophotometer under alkaline conditions. The effect of variation of substrate Neomycine sulphate salt (NS), oxidant (KMnO4) and NaOH was studied under pseudo first order reaction conditions. The effect of different salts and solvents on oxidation of NS was also studied. The reaction was found to be first order with respect to oxidant, substrate and NaOH.. Keywords: Neomycine sulphate salt (NS), KMnO4 , permanganatic  oxidation, alkaline permanganate

In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

2020 ◽  
Vol 16 ◽  
Author(s):  
M. Alarjah
Keyword(s):  
Half Life ◽  
Hplc Method ◽  
Hydrolysis Rate ◽  
First Order ◽  
First Order Kinetics ◽  
Rp Hplc ◽  
Pharmacokinetic Properties ◽  
Pseudo First Order ◽  
Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

scholarly journals MW irradiation and ionic liquids as green tools in hydrolyses and alcoholyses

2020 ◽  
Vol 10 (1) ◽  
pp. 001-010 ◽  
Author(s):  
Nikoletta Harsági ◽  
Betti Szőllősi ◽  
Nóra Zsuzsa Kiss ◽  
György Keglevich
Keyword(s):  
Ionic Liquids ◽  
Alkaline Hydrolysis ◽  
Alkyl Group ◽  
Phosphinic Acid ◽  
Reaction Times ◽  
Alternative Possibility ◽  
First Order ◽  
Pseudo First Order ◽  
Mw Irradiation ◽  
Hydrolysis Of

Abstract The optimized HCl-catalyzed hydrolysis of alkyl diphenylphosphinates is described. The reaction times and pseudo-first-order rate constants suggested the iPr > Me > Et ∼ Pr ∼ Bu order of reactivity in respect of the alkyl group of the phosphinates. The MW-assisted p-toluenesulfonic acid (PTSA)-catalyzed variation means a better alternative possibility due to the shorter reaction times, and the alkaline hydrolysis is another option. The transesterification of alkyl diphenylphosphinates took place only in the presence of suitable ionic liquids, such as butyl-methylimidazolium hexafluorophosphorate ([bmim][PF6]) and butyl-methylimidazolium tetrafluoroborate ([bmim][BF4]). The application of ethyl-methylimidazolium hydrosulfate ([emim][HSO4]) and butyl-methylimidazolium chloride ([bmim][Cl]) was not too efficient, as the formation of the ester was accompanied by the fission of the O–C bond resulting in the formation of Ph2P(O)OH. This surprising transformation may be utilized in the phosphinate → phosphinic acid conversion.

Efficient adsorption of chlorpyrifos onto modified activated carbon by gamma irradiation; a plausible adsorption mechanism

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed S. Yahia ◽  
Ahmed S. Elzaref ◽  
Magdy B. Awad ◽  
Ahmed M. Tony ◽  
Ahmed S. Elfeky
Keyword(s):  
Gamma Irradiation ◽  
Area Measurement ◽  
Maximum Adsorption Capacity ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Pseudo First Order ◽  
Kinetics Of

Abstract Commercial Granulated Active Carbon (GAC) has been modified using 10 Gy dose Gamma irradiation (GAC10 Gy) for increasing its ability of air purification. Both, the raw and treated samples were applied for removing Chlorpyrifos pesticide (CPF) from ambient midair. Physicochemical properties of the two materials were characterized by Fourier Transform Infrared (FT-IR) and Raman spectroscopy. The phase formation and microstructure were monitored using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), supported with Energy-Dispersive X-ray (EDX). The Surface area measurement was detected using BET particle size prosometry. Obtained outcomes showed that, the maximum adsorption capacity, given by Langmuir equations, was greatly increased from 172.712 to 272.480 mg/g for GAC and GAC10 Gy, respectively, with high selectivity. The overall removal efficiency of GAC10 Gy was notably comparable to that of the original GAC-sorbent. The present study indicated that, gamma irradiation could be a promising technique for treating GAC and turned it more active in eliminating the pesticides pollutants from surrounding air. The data of equilibrium has been analyzed by Langmuir and Freundlich models, that were considerably better suited for the investigated materials than other models. The process kinetics of CPF adsorbed onto both tested carbon versions were found to obey the pseudo first order at all concentrations with an exception at 70 mg/l using GAC, where, the spontaneous exothermic adsorption of Chlorpyrifos is a strong function for the pseudo-first order (PFO) and pseudo second order (PSO) kinetics.

A kinetic standard for precise calibration of spectrophotometer cell temperature.

1981 ◽  
Vol 27 (5) ◽  
pp. 753-755 ◽  
Author(s):  
P A Adams ◽  
M C Berman
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cell Temperature ◽  
First Order ◽  
Order Rate ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

Abstract We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).

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