Hydrolytic stability and pesticidal activity of N'-methyl- and N'-arylcarbamates of 3-(N,N-diethylamino)phenol

1983 ◽  
Vol 48 (5) ◽  
pp. 1440-1446
Author(s):  
Alexandr Čegan ◽  
Miroslav Večeřa
Keyword(s):  
Effective Dose ◽  
Hydrolytic Stability ◽  
Aqueous Media ◽  
Herbicidal Activity ◽  
Hydrolysis Rate ◽  
Reaction Constant ◽  
Hydrolysis Of ◽  
Diethylamino Group

Twelve carbamates based on 3-(N,N-diethylamino)phenol have been prepared, and their hydrolysis rate in aqueous media of pH 7-12.5, their inhibition of butyrylcholin esterase and acetylcholin esterase and herbicidal activity have been studied. The hydrolysis of the compounds studied in the mentioned media proceeds by the ElcB mechanism, the value of reaction constant at 25 °C is ρ = 1.12 ± 0.08. The hydrolysis rate in the pH region 7-8.5 is affected by protonation of the 3-N,N-diethylamino group. The compounds I-XII inhibit butyrylcholin esterase (pI50 value 5.1-6.5). Acetylcholin esterase is inhibited most efficiently by the carbamates XII (pI50 = 8.3), XI (pI50 = 6.25) and VII (pI50 = 5.07). Herbicidal effects are small, the effective dose being above 5 kg/ha.

Kinetics and mechanism of hydrolysis of substituted phenyl N-(4-methylphenyl)sulphonylcarbamates. Solvolysis of 3-nitrophenyl N-(4-methylphenyl)-sulphonylcarbamate in mixtures water-1,4-dioxane and water-tert-butyl alcohol and its decomposition to neutral molecules in non-aqueous media

1979 ◽  
Vol 44 (9) ◽  
pp. 2639-2652 ◽  
Author(s):  
Jitka Moravcová ◽  
Miroslav Večeřa
Keyword(s):  
Organic Solvents ◽  
Ph Dependence ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Base Catalysis ◽  
Hydrolysis Rate ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Hydrolysis Of

pH Dependence of hydrolysis rate of the substituted phenyl N-(4-methylphenyl)sulphonylcarbamates has been followed in aqueous medium. The activation parameters and the Hammet reaction constant (ρ = 2.4) have been determined at pH 11.3. For hydrolysis of 3-nitrophenyl N-(4-methylphenyl)sulphonylcarbamate (pK about 3.5) no general base catalysis has been found. The hydrolysis mechanism is discussed. Perturbation of the water structure by organic solvents (1,4-dioxane and tert-butyl alcohol) has been used for differentiation of ElcB and Bac2 mechanisms, 2,4-dinitrophenyl acetate being used for comparison. The decomposition rates of 3-nitrophenyl N(4-methylphenyl)sulphonylcarbamate have been determined in six organic solvents. Mechanism of spontaneous splitting of the carbamate molecule in non-aqueous media is discussed.

The chemistry of N,N′-dimethylformamidine. II. Hydrolysis. Kinetically controlled formation of cis-N-methylformamide

1978 ◽  
Vol 56 (11) ◽  
pp. 1463-1469 ◽  
Author(s):  
James D. Halliday ◽  
E. Allan Symons
Keyword(s):  
Aqueous Media ◽  
Hydrolysis Rate ◽  
Strong Base ◽  
First Order ◽  
H Nmr ◽  
Stereoelectronic Control ◽  
Pseudo First Order ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Cis Isomer

The hydrolysis of N,N′-dimethylformamidine (DMFA) has been investigated in acid and alkaline aqueous media by 1H nmr; only a narrow basic pH range could be extensively studied kinetically. The pseudo-first-order kobs rose steadily from pH 11.5 to 13.0 (reaction approximately first order in OH−), then became independent of pH above 13.5 (9.3 × 10−4 s−1 at 10 °C). In contrast to many amidines, DMFA is quite stable in acid solution (estimated value of the pseudo-first-order hydrolysis rate constant is 1.4 × 10−1 s−1 at 10 °C, pH 0.05, from measurements at 100 and 140 °C). This stability is ascribed to the difficulty of eliminating the fairly strong base methylamine from the tetrahedral intermediate in acid solution.N-Methylformamide (NMF), one of the products, is formed initially as the cis isomer. A somewhat slower conversion then occurs to the thermodynamically more stable trans isomer. This unusual result is explained in terms of Deslongchamps and co-workers' theory of stereoelectronic control for the orbital-assisted breakdown of tetrahedral intermediates.

Development and Validation of a Liquid Chromatographic Method for Aroylhydrazones at Hydrolytic Conditions

2019 ◽  
Vol 16 ◽  
Author(s):  
Vania Maslarska ◽  
Stanislav Bozhanov ◽  
Stefka Ivanova ◽  
Violina T. Angelova
Keyword(s):  
High Performance ◽  
Hydrolytic Stability ◽  
Aqueous Media ◽  
Antimycobacterial Activity ◽  
Pharmaceutical Formulations ◽  
Pseudo First Order Reaction ◽  
Development And Validation ◽  
Liquid Chromatographic ◽  
Hydrolysis Of

Aims: The indole-containing aroylhydrazone derivatives 3a-c with potent antimycobacterial activity against a referent strain M. tuberculosis H37Rv and low cytotoxicity were evaluated for their stability via the precise and accurate HPLC analytical method in aqueous media of different pH (2.0, 7.0, 9.0 and 12.0). Objective: The study describes the development and validation of a simple and reliable HPLC-UV procedure for the determination of aroylhydrazone derivatives and their hydrolytic stability. Additionally, to recognize if hydrolysis leads to generating undesired products, the degradation processes were identified. Method: The separation was achieved with a LiChrosorb®RP-18 (250 x 4.6 mm) column, at ambient temperature with isocratic mode with mobile phase containing mixture of component A (acetonitrile) and component B (0.001M NaH2PO4, with 5 mM 1-heptane sulfonic acid sodium salt, adjusted to pH 3.0) in a ratio 60:40 (v/v). The flow rate was 1.0 ml/min and the eluent was monitored at 297 nm. The proposed method was validated as per ICH guidelines. Result: The obtained results showed that the compounds were sensitive to hydrolytic decomposition in aqueous media, resulting in the splitting of the hydrazone bond. Rapid hydrolysis of substances was observed in the acid medium. The elevated temperature significantly accelerated the hydrolytic reaction. Relatively slow hydrolysis of 3a-c was observed in a neutral solution and aqueous solutions buffered to pH 9. The hydrolysis of 3a-c in neutral, alkaline and strong alkaline medium followed the pseudo-first-order reaction rate and showed a linear dependence of lnC versus time. Conclusion: A validated high-performance liquid chromatographic assay for the determination of the hydrolytic stability of a series of aroylhydrazones was developed and optimized for the first time. The methods devised are successfully applicable to the development of pharmaceutical formulations.

scholarly journals Kinetics of Enzymatic Hydrolysis of Southeast Sulawesi Sago Starch

2020 ◽  
pp. 53-61
Author(s):  
Ansharullah Ansharullah ◽  
Muhammad Natsir
Keyword(s):  
Enzymatic Hydrolysis ◽  
Maximum Velocity ◽  
Enzyme Concentration ◽  
Hydrolysis Rate ◽  
Sago Starch ◽  
Optimum Conditions ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Menten Constant

The aims of this study were to characterize the kinetics of enzymatic hydrolysis of sago starch, obtained from Southeast Sulawesi Indonesia. The enzyme used for hydrolysis was bacterial ∝-amylase (Termamyl 120L from Bacillus licheniformis, E. C. 3.2.1.1).  The method to determine the initial velocity (Vo) of the hydrolysis was developed by differentiation a nonlinear equation (NLE).  The Vo of the hydrolysis was measured at various pH (6.0, 6.5,and 7.0), temperatures (40, 60, 75 and 95oC), enzyme concentrations (0.5, 1.0, 1.5 and 2.0 µg per mL) and in the presence of 70 ppm Ca++. The optimum conditions of this experiment were found to be at pH 6.5 – 7.0 and 75oC, and the Vo increased with increasing enzyme concentration. The Vo values at various substrate concentrations were also determined, which were then used to calculate the enzymes kinetics constant of the hydrolysis, including Michaelis-Menten constant (Km) and maximum velocity (Vmax) using a Hanes plot.  Km and Vmax values were found to be higher in the measurement at pH 7.0 and 75oC. The Km values  at four  different combinations of pH and temperatures (pH 6.5, 40oC; pH 6.5, 75oC; pH 7.0, 40oC; pH 7.0, 75oC) were found to be 0.86, 3.23, 0.77 and 3.83 mg/mL, respectively; and Vmax values were 17.5, 54.3, 20.3 and 57.1 µg/mL/min, respectively. The results obtained showed that hydrolysis rate of this starch was somewhat low.

Hydrolysis of MgH2 in MgCl2 solutions as an effective way for hydrogen generation

2021 ◽  
pp. 38-52
Author(s):  
V. Berezovets ◽  
◽  
A. Kytsya ◽  
Yu. Verbovytskyy ◽  
I. Zavaliy ◽  
...  
Keyword(s):  
Hydrogen Generation ◽  
Strong Acid ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction ◽  
Hydrolysis Rate ◽  
Reaction Yield ◽  
Buffer Solution ◽  
Passivation Film ◽  
Products Of Reaction ◽  
Hydrolysis Of

Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6 wt%) and the Mg element is abundant on the earth. Due to its strong reduction ability, even at room temperature it can provide the hydrogen yield reaching 15.2 wt% H (1703 mL/g) when interacting with water, which makes it very attractive for the application in supplying hydrogen for autonomous H energy systems. However, the hydrolysis reaction is rapidly inhibited by the Mg(OH)2 passivation layer formed on the surface of MgH2. In order to remove the passivation film and improve the efficiency of the MgH2 hydrolysis process, several methods including alloying, ball milling, changing the aqueous solution, have been successfully utilized. In this paper the process of hydrolysis of magnesium hydride in aqueous solutions of MgCl2 used as a promotor of the interaction has been studied in detail. It was found that the initial hydrolysis rate, pH of the reaction mixture, and overall reaction yield are all linearly dependent of the logarithm of MgCl2 concentration. It has been shown that pH of the reaction mixture in the presence of MgCl2 is well described by considering a system “weak base and its salt with strong acid” type buffer solution. Reference data for this hydrolysis reaction were also carefully analyzed. The mechanism and the kinetic model of the process of MgH2 hydrolysis in water solutions involved passivation of the MgH2 surface by the formed Mg(OH)2 precipitate followed by its repassivation have been proposed. The obtained after the hydrolysis reactions precipitates were studied using XRD and EDS. It was found also that the final products of reaction consist of Mg(OH)2 (brucsite type) and remaining MgH2. This fact shows that the formation of solid species such as MgCl2 xMgO yH2O at the studied conditions is unlikely and decreasing of pH the reaction mixture has a different nature.

A “turn-on” fluorescent and colorimetric chemodosimeter for selective detection of Au3+ ions in solution and in live cells via Au3+-induced hydrolysis of a rhodamine-derived Schiff base

2020 ◽  
Vol 44 (19) ◽  
pp. 7954-7961
Author(s):  
Sanchita Mondal ◽  
Saikat Kumar Manna ◽  
Sudipta Pathak ◽  
Aritri Ghosh ◽  
Pallab Datta ◽  
...  
Keyword(s):  
Schiff Base ◽  
Rhodamine B ◽  
Aqueous Media ◽  
Sensitive Detection ◽  
Live Cells ◽  
Selective Detection ◽  
Turn On ◽  
Hydrolysis Of

A chromogenic and “off–on” fluorogenic chemodosimeter (L) based on a naphthalene–rhodamine B derivative was designed, synthesized and characterized for the selective and sensitive detection of Au3+ ions in mixed acetonitrile aqueous media.

Transformations of the Herbicide N-(1,1-dimethylpropynyl)-3,5-dichlorobenzamide in Soil

Weed Science ◽  
1970 ◽  
Vol 18 (5) ◽  
pp. 604-607 ◽  
Author(s):  
Roy Y. Yih ◽  
Colin Swithenbank ◽  
D. Harold McRae
Keyword(s):  
Soil Moisture ◽  
High Temperature ◽  
Soil Moisture Content ◽  
Chemical Change ◽  
Herbicidal Activity ◽  
Compound I ◽  
Subsequent Hydrolysis ◽  
Compound Ii ◽  
Hydrolysis Of

Transformation of N-(1,1-dimethylpropynyl)-3,5-dichlorobenzamide (compound I) in soil occurs readily and two products are produced, initial cyclization giving 2-(3,5-dichlorophenyl)-4,4-dimethyl-5-methyleneoxazoline (compound II) followed by subsequent hydrolysis to N-(1,1-dimethylacetonyl)-3,5-dichlorobenzamide (compound III). These transformations can be brought aboutin vitro, the first step by means of acid or base, and the second by extended treatment with acid. The rate of cyclization and hydrolysis of compound I varies directly with soil temperature, being rapid at high temperature (37 C) and very slow at low temperature (5 C). The rate of chemical change of compound I in soil is influenced to a much greater degree by temperature than by soil moisture content. The effect of soil type on transformation of compound I was studied and compounds II and III were present in five of the six soils examined. The herbicidal activity of compounds II and III was negligible in comparison to compound I.

Commercial Dental Composite: Determination of Reaction Advancement and Study of the Migration of Organic Compounds

2005 ◽  
Vol 13 (3) ◽  
pp. 223-234
Author(s):  
C. Sanglar ◽  
M. Defay ◽  
H. Waton ◽  
A. Bonhomme ◽  
S. Alamercery ◽  
...  
Keyword(s):  
Artificial Saliva ◽  
Aqueous Media ◽  
Dental Composite ◽  
Dental Composites ◽  
Hydrophilic Monomer ◽  
Methacrylate Monomers ◽  
Urethane Dimethacrylate ◽  
Hydrolysis Of

This work on organic dental composites was undertaken to determine the role of residual reactive methacrylate functions at the end of the photopolymerization cycle, and to investigate the fate of the residual monomers and oligomers in organic (ethanol) and aqueous (water and artificial saliva) media. The results show that all the methacrylate monomers present in dentine migrate into ethanol (about 1% (w/w)). In aqueous media on the other hand, only the most hydrophilic monomer (UDMA) migrates (0.05% (w/w)) into water and 0.03% into artificial saliva (pH = 9). This desorption in the three media is accompanied by the hydrolysis of monomers, leading to the formation of monohydrolyzed urethane dimethacrylate (UDMA) and bis-phenyl glycidyl dimethacrylate (BISGMA); UDMA and BISGMA are completely hydrolyzed in artificial saliva. The alkalinity of the milieu apparently favours the hydrolysis of methacrylate functions.

Functional role of ecto-ATPase activity in goldfish hepatocytes

1998 ◽  
Vol 274 (4) ◽  
pp. R1031-R1038 ◽  
Author(s):  
Pablo J. Schwarzbaum ◽  
Michael E. Frischmann ◽  
Gerhard Krumschnabel ◽  
Rolando C. Rossi ◽  
Wolfgang Wieser
Keyword(s):  
Atpase Activity ◽  
Functional Role ◽  
Maximal Activity ◽  
Hydrolysis Rate ◽  
Hyperbolic Function ◽  
Extracellular Release ◽  
Transport Atpases ◽  
Hydrolysis Of ◽  
Hepatocyte Suspension

Extracellular [γ-32P]ATP added to a suspension of goldfish hepatocytes can be hydrolyzed to ADP plus γ-32Pidue to the presence of an ecto-ATPase located in the plasma membrane. Ecto-ATPase activity was a hyperbolic function of ATP concentration ([ATP]), with apparent maximal activity of 8.3 ± 0.4 nmol Pi ⋅ (106cells)−1 ⋅ min−1and substrate concentration at which a half-maximal hydrolysis rate is obtained of 667 ± 123 μM. Ecto-ATPase activity was inhibited 70% by suramin but was insensitive to inhibitors of transport ATPases. Addition of 5 μM [α-32P]ATP to the hepatocyte suspension induced the extracellular release of α-32Pi[8.2 pmol ⋅ (106cells)−1 ⋅ min−1] and adenosine, suggesting the presence of other ectonucleotidase(s). Exposure of cell suspensions to 5 μM [2,8-3H]ATP resulted in uptake of [2,8-3H]adenosine at 7.9 pmol ⋅ (106cells)−1 ⋅ min−1. Addition of low micromolar [ATP] strongly increased cytosolic free Ca2+([Formula: see text]). This effect could be partially mimicked by adenosine 5′- O-(3-thiotriphosphate), a nonhydrolyzable analog of ATP. The blockage of both glycolysis and oxidative phosphorylation led to a sixfold increase of[Formula: see text] and an 80% decrease of intracellular ATP, but ecto-ATPase activity was insensitive to these metabolic changes. Ecto-ATPase activity represents the first step leading to the complete hydrolysis of extracellular ATP, which allows 1) termination of the action of ATP on specific purinoceptors and 2) the resulting adenosine to be taken up by the cells.

scholarly journals Kinetics of alkoxysilanes hydrolysis: An empirical approach

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahmed A. Issa ◽  
Marwa El-Azazy ◽  
Adriaan S. Luyt
Keyword(s):  
Reaction Mechanisms ◽  
Hydrolysis Reaction ◽  
Hydrolysis Rate ◽  
Coupling Agents ◽  
Linear Free Energy Relationship ◽  
Acidic Media ◽  
Linear Free Energy ◽  
Primary Materials ◽  
Kinetics Of ◽  
Hydrolysis Of

AbstractAlkoxysilanes and organoalkoxysilanes are primary materials in several industries, e.g. coating, anti-corrosion treatment, fabrication of stationary phase for chromatography, and coupling agents. The hydrolytic polycondensation reactions and final product can be controlled by adjusting the hydrolysis reaction, which was investigated under a variety of conditions, such as different alkoxysilanes, solvents, and catalysts by using gas chromatography. The hydrolysis rate of alkoxysilanes shows a dependence on the alkoxysilane structure (especially the organic attachments), solvent properties, and the catalyst dissociation constant and solubility. Some of the alkoxysilanes exhibit intramolecular catalysis. Hydrogen bonding plays an important role in the enhancement of the hydrolysis reaction, as well as the dipole moment of the alkoxysilanes, especially in acetonitrile. There is a relationship between the experimentally calculated polarity by the Taft equation and the reactivity, but it shows different responses depending on the solvent. It was found that negative and positive charges are respectively accumulated in the transition state in alkaline and acidic media. The reaction mechanisms are somewhat different from those previously suggested. Finally, it was found that enthalpy–entropy compensation (EEC) effect and isokinetic relationships (IKR) are exhibited during the hydrolysis of CTES in different solvents and catalysts; therefore, the reaction has a linear free energy relationship (LFER).

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