A Kinetic Oxymoron: Concentration-Dependent First-Order Rate Constants for Hydrolysis of Ceftazidime

1998 ◽  
Vol 87 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Josephine O. Fubara ◽  
Robert E. Notari
Keyword(s):  
Rate Constants ◽  
First Order ◽  
Order Rate ◽  
Hydrolysis Of

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.

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).

Electrochemistry of Ruthenium Ammine Complexes

1975 ◽  
Vol 53 (19) ◽  
pp. 2922-2929 ◽  
Author(s):  
C. M. Elson ◽  
I. J. Itzkovitch ◽  
J. McKenney ◽  
John A. Page
Keyword(s):  
Cyclic Voltammetry ◽  
Rate Constants ◽  
Reduction Step ◽  
Methane Sulfonate ◽  
Ammine Complexes ◽  
Chloro Complexes ◽  
First Order ◽  
Order Rate ◽  
Electron Reduction ◽  
Hydrolysis Of

The electrochemistry of ruthenium(III) penta- and tetraammine chloro complexes has been investigated. In each case, the ruthenium(III) species was found to undergo an initial one electron reduction step, followed by hydrolysis of the chloride(s) in the ruthenium(II) product. The rate constants for the substitution steps were evaluated by cyclic voltammetry. An aqueous 0.30 M methane sulfonate electrolyte of pH 2.0 was used at 25 °C.Values for the reversible "E1/2" (V υs. SCE) and first order rate constants for the (stepwise) replacement of the Cl− are: Ru(NH3)5Cl+, −0.282 V and 17 s−1; cis-Ru(NH3)4Cl2+, −0.328 V, 80 s−1, and 5 s−1; trans-Ru(NH3)4Cl2+, −0.412 V, 2 s−1, and 0.4 s−1.The electrochemistry of Ru(NH3)5SO22+was also investigated. In a 0.10 M CH3SO3H – 0.20 M CH3SO3Na electrolyte the ruthenium(II) species was found to undergo an initial one electron oxidation step with "E1/2" = +0.50 V, followed by a slow hydrolysis of the SO2 in the ruthenium(III) product with k = 2.4 × 10−2 s−1 at 25 °C.

Octahedral cobalt(III) complexes of the chloropentammine type. XIX. The preparation, properties, and reactions of some Chlorobenzylaminebis-(ethylenediamine)cobalt(III) salts and related complexes

1969 ◽  
Vol 22 (9) ◽  
pp. 1869 ◽  
Author(s):  
SC Chan ◽  
OW Lau
Keyword(s):  
Rate Constants ◽  
Open Chain ◽  
First Order ◽  
Benzyl Radical ◽  
Order Rate ◽  
Visible Spectra ◽  
Rate Of Reaction ◽  
Inductive Effects ◽  
Steric Factors ◽  
Hydrolysis Of

Salts of one isomeric series of chlorobenzylaminebis(ethylenediamine)- cobalt-(III) type of cations have been prepared using a variety of benzylamine derivatives as ligands. They are tentatively assigned a cis-configuration on the basis of their visible spectra. The first- order rate constants for their solvolytic aquation have been measured. Both resonance contributions and steric factors from the benzyl radical, as well as inductive effects of its substituents, all have negligibly small influences on the rate of reaction. The second-order rate constants for the hydrolysis of these cations by base have also been determined. The labilizing powers of the benzylamine ligands in this reaction are very similar to those of open-chain aliphatic amines, and significantly different from those of aromatic amines. To see if reactivities depend on the distance of separation between cobalt and the benzene ring, the experiments are extended to the chloro(β- phenylethylamine)bis(ethylenediamine)cobalt(III) type of complexes.

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.

Octahedral cobalt(III) complexes of the chloropentammine type. XX. The preparation, properties, and reactions of some chlorocycloalkylaminebis- (ethylenediamine)cobalt(III) salts

1970 ◽  
Vol 23 (4) ◽  
pp. 707 ◽  
Author(s):  
SC Chan ◽  
TL Cheung
Keyword(s):  
Rate Constants ◽  
Ion Pair ◽  
Base Hydrolysis ◽  
Isomeric Form ◽  
Visible Absorption ◽  
First Order ◽  
Order Rate ◽  
Hydrolysis Of ◽  
Conjugate Base ◽  
Visible Absorption Spectroscopy

Salts of one isomeric form of the chlorocycloalkylaminebis(ethylenediamine)cobalt(111) series of cations have been prepared and characterized. They are tentatively assigned a cis configuration on the basis of visible absorption spectroscopy. The first-order rate constants for the solvolytic aquation of these cations have been determined at 50.5�, and the results suggest the presence of steric acceleration. The second-order rate constants for the base hydrolysis of these cations have also been determined at 0� and ionic strength of 0.1M. These results are discussed in terms of the conjugate-base/ion-pair mechanistic spectrum postulated previously.

The Hydrolysis of Some N-Acylaspartic and N-Acylglutamic Monoamides in Dilute Mineral Acid

1975 ◽  
Vol 53 (11) ◽  
pp. 1137-1144 ◽  
Author(s):  
M. Ali ◽  
J. B. Capindale
Keyword(s):  
Hydrochloric Acid ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Rate Constants ◽  
Mineral Acid ◽  
First Order ◽  
Order Rate ◽  
Succinamic Acid ◽  
Aqueous Hydrochloric Acid ◽  
Hydrolysis Of

The release of ammonia by hydrolysis of N-benzoyl-L-asparagine, glycyl-DL-asparagine, L-asparagine, and succinamic acid, and of aniline from N-benzoyl-L-glutamic-α-anilide, N-benzoyl-L-aspartic-α-anilide, L-aspartic-α-anilide, and the monoanilides of succinic and glutaric acids is first-order with respect to substrate in dilute (0.4–0.03 M) aqueous hydrochloric acid at 100 °C. The first-order rate constants (kobs) for these reactions can be expressed as kobs = kintra + k2[H+]. The above hydrolyses are used as models for developing a tentative mechanism to account for the selective release of aspartic acid from proteins under these conditions. The data are also used to suggest reasons why glutamic acid is not released with equal facility.

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.

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.

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