Hydrolysis of Monothio-β-diketones. I. Monothioacetylacetone and monothiobenzoylacetone

1974 ◽  
Vol 27 (11) ◽  
pp. 2353 ◽  
Author(s):  
M Leban ◽  
J Fresco ◽  
SE Livingstone
Keyword(s):  
Acid Solution ◽  
Rate Constants ◽  
First Order ◽  
Order Rate ◽  
Enthalpy Of Activation ◽  
Pseudo First Order ◽  
Hydrolysis Of

The hydrolysis of monothioacetylacetone (4-mercaptopent-3-en-2-one) and monothiobenzoylacetone (3-mercapto-1-phenylbut-2-en-1-one) in acid solution has been studied spectrophotometrically. The half-lives were found to be 50�2 min and 124�5 min at 25� for monothioacetylacetone and monothiobenzoylacetone, respectively. The corresponding pseudo first- order rate constants are 1.39�0.05 x 10-2 and 5.59�0.14 x 10-3 min-1. The enthalpy of activation for the hydrolysis of monothiobenzoylacetone was determined as 79.5 � 4 kJ/mol.

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).

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.

scholarly journals Optimization and a Kinetic Study on the Acidic Hydrolysis of Dialkyl α-Hydroxybenzylphosphonates

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3793
Author(s):  
Nikoletta Harsági ◽  
Zita Rádai ◽  
Áron Szigetvári ◽  
János Kóti ◽  
György Keglevich
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Acidic Hydrolysis ◽  
First Order ◽  
Order Rate ◽  
Rate Determining Step ◽  
Pseudo First Order ◽  
Hydrolysis Of ◽  
Electron Withdrawing Substituents

The two-step acidic hydrolysis of α-hydroxybenzylphosphonates and a few related derivatives was monitored in order to determine the kinetics and to map the reactivity of the differently substituted phosphonates in hydrolysis. Electron-withdrawing substituents increased the rate, while electron-releasing ones slowed down the reaction. Both hydrolysis steps were characterized by pseudo-first-order rate constants. The fission of the second P-O-C bond was found to be the rate-determining step.

Kinetics of hydrolysis of aromatic bicycling disulfonyl dichlorides

1988 ◽  
Vol 66 (12) ◽  
pp. 3056-3059 ◽  
Author(s):  
Przemysław Sanecki ◽  
Edward Rokaszewski
Keyword(s):  
Rate Constants ◽  
Polarographic Method ◽  
First Order ◽  
Order Rate ◽  
Kinetics Of Hydrolysis ◽  
Consecutive Reactions ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

Hydrolysis of 16 compounds ClO2S—Ar—B—Ar—SO2Cl (B, bridge) in 20% H2O, 80% v/v CH3CO2H, 0.5 mol dm−3 CH3CO2Na at 298.15 K has been investigated by a polarographic method. From plots of the hydrolysis, pseudo-first-order rate constants for two consecutive reactions [Formula: see text] have been computed and the influence of -SO2Cl groups, bridges B, and SO3− groups on the reactivity of -SO2Cl groups has been discussed. The ratio of rate constants k2/k1 ranges from 0.45 to 30, depending on the structure. Log (k1/(2kH)) correlated linearly with [Formula: see text] and log (k2/k1) correlated linearly with ΔpK for the analogous diamine series H2N—Ar—B—Ar—NH2.

Hydrolysis of Monothio-β-diketones. II. Hydrolysis of three fluorinated Monothio-β-diketones

1974 ◽  
Vol 27 (11) ◽  
pp. 2357 ◽  
Author(s):  
M Leban ◽  
J Fresco ◽  
M Das ◽  
SE Livingstone
Keyword(s):  
Acid Solution ◽  
Hydrogen Sulphide ◽  
Trifluoroacetic Acid ◽  
Rate Constants ◽  
The Other ◽  
Hydrolytic Cleavage ◽  
First Order ◽  
Rapid Decomposition ◽  
Pseudo First Order ◽  
Hydrolysis Of

The rapid decomposition of the fluorinated monothio-β-diketones RC(SH)=CHCOCF3, 4-(3?-bromophenyl)-1,1,1-trifluoro-4-mercaptobut-3-en-2- one (R = m-BrC6H4), 4-(4?-bromophenyl)-1,1,1-trifluoro-4-mercaptobut-3- en-2-one (R = p-BrC6H4) and 1,1,1-trifluoro-4-mercaptopent-3-en-2-one(R = Me), in acid solution has been shown to occur by hydrolytic cleavage to yield the ketone RCOCH3, hydrogen sulphide and probably trifluoroacetic acid. The pseudo first-order rate constants for these compounds are (8.0�0.3)x 10-3, min-1, (6.0 � 0.6) x 10-3 min-1 and 0.12�0.01 min-1, respectively. The greater vulnerability of 1,1,1- trifluoro-4-mercaptopent-3-en-2-one, compared to the other two monothio-β-diketones, towards hydrolytic cleavage is related to the nature of the R substituent in that conjugation involving the terminal aromatic ring stabilizes the monothio-β-diketone.

The mercury(II)-induced aquation of trans-Chloroamminebis(dimethylglyoximato)cobalt(III) complex

1975 ◽  
Vol 28 (5) ◽  
pp. 1133 ◽  
Author(s):  
S Chan ◽  
S Tan
Keyword(s):  
Rate Constants ◽  
Aqueous Ethanol ◽  
Association Constants ◽  
First Order ◽  
Order Rate ◽  
Leaving Group ◽  
Pseudo First Order ◽  
Activated Complex

The pseudo first-order rate constants for the mercury(II)-induced aquation of trans-[Co(Hdmg)2(NH3)Cl] (Hdmg = dimethylglyoximate ion) have been measured in aqueous and aqueous ethanol solutions (ethanol- water mole ratio 1 : 5.1) containing various excess amounts of mercury(II)ion at 273.2 K. Association constants of the complex formed with mercury(II) ion and rate constants for dissociation of the activated complex in both solutions have been calculated. The kinetic results are discussed in terms of formation of an activated complex Co-C1-Hg, followed by a simple rate-determining aquation in which HgCl+ acts as the leaving group.

Degradation of propoxycarbazone-sodium with advanced oxidation processes

2011 ◽  
Vol 11 (1) ◽  
pp. 129-134 ◽  
Author(s):  
A. Dulov ◽  
N. Dulova ◽  
Y. Veressinina ◽  
M. Trapido
Keyword(s):  
Rate Constants ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Fenton Process ◽  
Oxidation Processes ◽  
First Order ◽  
Order Rate ◽  
Conversion Time ◽  
Pseudo First Order ◽  
Kinetics Of

The degradation of propoxycarbazone-sodium, an active component of commercial herbicide, in aqueous solution with ozone, UV photolysis and advanced oxidation processes: O3/UV, O3/UV/H2O2, H2O2/UV, and the Fenton process was studied. All these methods of degradation proved feasible. The kinetics of propoxycarbazone-sodium degradation in water followed the pseudo-first order equation for all studied processes except the Fenton treatment. The application of schemes with ozone demonstrated low pseudo-first order rate constants within the range of 10−4 s−1. Addition of UV radiation to the processes improved the removal of propoxycarbazone-sodium and increased the pseudo-first order rate constants to 10−3 s−1. The Fenton process was the most efficient and resulted in 5 and 60 s of half-life and 90% conversion time of propoxycarbazone-sodium, respectively, at 14 mM H2O2 concentration. UV treatment and the Fenton process may be recommended for practical application in decontamination of water or wastewater.

Acyl Transfer Isomerization of Glycerol 1,2-Dibutyrate and Propane-1,2-diol 1-Butyrate

1998 ◽  
Vol 51 (6) ◽  
pp. 455 ◽  
Author(s):  
Charmian J. O'Connor ◽  
Richard H. Barton
Keyword(s):  
Rate Constants ◽  
Equilibrium Mixture ◽  
Acyl Transfer ◽  
Product Mix ◽  
First Order ◽  
Order Rate ◽  
Pregastric Lipase ◽  
Water Ph ◽  
Emulsion Systems ◽  
Hydrolysis Of

The speciation of mixed butyrylglycerols (glycerol butyrates) and propanediol butyrate esters in the product mix from lamb pregastric lipase-catalysed hydrolysis of tributyrylglycerol and propane-1,2-diol dibutyrate has been examined by 13C n.m.r. spectroscopy. Samples from the quenched reaction mixture were extracted and allowed to stand in emulsion systems made up in bis tris propane buffer or water, pH 7·0, and in the absence of enzyme. There is clear evidence of uncatalysed conversion of rac-1,2-dibutyrylglycerol into the 1,3-isomer to form an equilibrium mixture containing c. 60–67% 1,3-isomer, and of conversion of propane-1,2-diol 1-butyrate into propane-1,2-diol 2-butyrate to form an equilibrium mixture containing c. 67% 2-monoester. Conversion kinetics to reach equilibrium are first order. Rate constants for acyl transfer of the diacylglycerol are 0·48 h-1 (in water) and 0·68 h-1 (in buffer) at 50°C, while those for acyl transfer of the 1-monoester are 0·72 h-1 (50°C) and 0·35 h-1 (35°C).

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