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.

Kinetics and mechanism of the base hydrolysis of some trans-dihalogeno(cyclam)rhodium(III) complexes

1978 ◽  
Vol 56 (5) ◽  
pp. 709-713 ◽  
Author(s):  
H. L. Chung ◽  
E. J. Bounsall
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
The Other ◽  
Base Hydrolysis ◽  
Trans Effect ◽  
First Order ◽  
Class B ◽  
Pseudo First Order ◽  
Hydrolysis Of ◽  
Kinetic Class

The base hydrolysis of trans-[Rh(cyclam)XY]+ (cyclam = 1,4,8,11-tetraazacyclotetradecane; X− and Y− = Cl−, Br−, and I−) are studied in aqueous solution over a range of OH− concentration and at various temperatures. The kinetics are done at a constant ionic strength with excess of [OH−] (smallest ratio = 200:1) so that pseudo first order rate constants are obtained for all the determinations. All of the reactions proceed with complete retention of configuration, and no trans-to-cis isomerization is found. The kinetic trans effect of these complexes is I− > Br− > Cl− on a rate basis, but based on ΔH≠, I− > Br− = Cl−. These Rh(III) complexes exhibit kinetic class (b) character on the ΔH≠ basis. The results of the rate constants and the activation parameters are interpreted in ternis of an SN1CB mechanism. The behavior of these complexes is compared to that of the other analogous complexes.

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.

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.

scholarly journals Ganglioside incorporation and release by the isolated perfused rat liver

1991 ◽  
Vol 274 (2) ◽  
pp. 581-585 ◽  
Author(s):  
S C Kivatinitz ◽  
A Miglio ◽  
R Ghidoni
Keyword(s):  
Rat Liver ◽  
The Other ◽  
Regulatory Role ◽  
Isolated Perfused Rat Liver ◽  
Order Kinetic ◽  
Perfused Rat Liver ◽  
Ganglioside Gm1 ◽  
First Order ◽  
Pseudo First Order

The fate of exogenous ganglioside GM1 labelled in the sphingosine moiety, [Sph-3H]GM1, administered as a pulse, in the isolated perfused rat liver was investigated. When a non-recirculating protocol was employed, the amount of radioactivity in the liver and perfusates was found to be dependent on the presence of BSA in the perfusion liquid and on the time elapsed after the administration of the ganglioside. When BSA was added to the perfusion liquid, less radioactivity was found in the liver and more in the perfusate at each time tested, for up to 1 h. The recovery of radioactivity in the perfusates followed a complex course which can be described by three pseudo-first-order kinetic constants. The constants, in order of decreasing velocity, are interpreted as: (a) the dilution of the labelled GM1 by the constant influx of perfusion liquid; (b) the washing off of GM1 loosely bound to the surface of liver cells; (c) the release of gangliosides from the liver. Process (b) was found to be faster in the presence of BSA, probably owing to the ability of BSA to bind gangliosides. The [Sph-3H]GM1 in the liver underwent metabolism, leading to the appearance of products of anabolic (GD1a, GD1b) and catabolic (GM2, GM3) origin; GD1a appeared before GM2 and GM3 but, at times longer than 10 min, GM2 and GM3 showed more radioactivity than GD1a. At a given time the distribution of the radioactivity in the perfusates was quite different from that of the liver. In fact, after 60 min GD1a was the only metabolite present in any amount, the other being GM3, the quantity of which was small. This indicates that the liver is able to release newly synthesized gangliosides quite specifically. When a recirculating protocol was used, there were more catabolites and less GD1a than with the non-recirculating protocol. A possible regulatory role of ganglioside re-internalization on their own metabolism in the liver is postulated.

Acid-catalyzed Solvolysis of Isonitriles. I

1971 ◽  
Vol 49 (14) ◽  
pp. 2455-2459 ◽  
Author(s):  
Y. Y. Lim ◽  
A. R. Stein
Keyword(s):  
Formic Acid ◽  
Acid Catalysis ◽  
Hydrolysis Product ◽  
Rate Dependence ◽  
Linear Rate ◽  
First Order ◽  
Methyl Amine ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of methyl isonitrile has been examined. The initial hydrolysis product is N-methylformamide which is further hydrolyzed to methyl amine and formic acid at a much slower rate. The hydrolysis to N-methylformamide is pseudo-first order in methyl isonitrile and shows a linear rate dependence on concentration of general (buffer) acid at fixed pH. The significance of general acid-catalysis in terms of the mechanism of the hydrolysis is considered and taken as evidence for carbon protonation rather than nitrogen protonation as the initiating step.

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