Medium effects in the acid catalyzed hydrolysis of benzohydroxamic acid in binary aqueous mixtures

1993 ◽  
Vol 49 (2) ◽  
pp. 403-409 ◽  
Author(s):  
Kallol K. Ghosh ◽  
Kishor K. Krishnani
Keyword(s):  
Aqueous Mixtures ◽  
Medium Effects ◽  
Benzohydroxamic Acid ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Medium effects in the acid-catalyzed hydrolysis of phenylacetohydroxamic acid in aqueous sulfolane

1974 ◽  
Vol 39 (6) ◽  
pp. 840-841 ◽  
Author(s):  
D. C. Berndt
Keyword(s):  
Medium Effects ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Medium effects on activation parameters on alkaline hydrolysis of 2-carbomethoxypropionate ion in aqueous mixtures of ethylene glycol

1987 ◽  
Vol 65 (2) ◽  
pp. 235-237 ◽  
Author(s):  
Prasanta Kumar Biswas ◽  
Bikas Chandra Bag ◽  
Mihir Nath Das
Keyword(s):  
Ethylene Glycol ◽  
Alkaline Hydrolysis ◽  
Silver Salt ◽  
Activation Parameters ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Medium Effects ◽  
Transfer Parameters ◽  
Experimental Values ◽  
Hydrolysis Of

The standard free energies of transfer [Formula: see text] of the 2-carbomethoxypropionate ion (R−) have been determined from the solubilities of the silver salt (AgR) in water and six aqueous mixtures of ethylene glycol (1–60%) at 25 °C, using the literature values of [Formula: see text] of Ag+. Utilizing these values of the R− ion as well as the literature values of [Formula: see text] of the OH− ion, combined with the experimental values of ΔG≠ for the alkaline hydrolysis of R− ion, the corresponding transfer parameters of the transition states [Formula: see text] for the hydrolysis reaction in aquo-glycolic media at 25 °C have been calculated. Attempts have been made to correlate the rates and activation parameters with the transfer quantities and solvent properties.

Kinetic solvent effects on acid-catalyzed hydrolysis of sucrose in aqueous mixtures of some protic, aprotic, and dipolar aprotic solvents

1986 ◽  
Vol 64 (8) ◽  
pp. 1638-1642 ◽  
Author(s):  
Urmila Mandal ◽  
Kaushik Das ◽  
Kiron Kumar Kundu
Keyword(s):  
Transition State ◽  
Optical Rotation ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Initial State ◽  
Composition Profiles ◽  
Acid Catalyzed ◽  
Solvent Systems ◽  
Hydrolysis Of ◽  
Reference Electrolyte

Rate constants of acid-catalyzed hydrolysis of sucrose (S) to D-glucose and L-fructose have been determined at 25 °C by optical rotation measurements in aqueous mixtures of protophobic protic glycerol (GL), protophilic protic urea (UH), aprotic dioxane (D), and dipolar aprotic dimethyl sulphoxide (DMSO). Transfer free energies of the substrate sucrose, [Formula: see text] have also been determined in the solvents from solubility measurements. These values as well as those of H+, as obtained earlier by use of the widely used tetraphenylarsonium tetraphenylboron (TATB) reference electrolyte assumption, yielded transfer free energies of the transition state. The observed log (ks/kw) – composition profiles reveal that the rates increase monotonically in GL–water mixtures, that decrease more or less monotonically in UH– and DMSO–water mixtures, and decrease up to 10 mol% D in D–water mixtures, beyond which the values tend to increase. Examination of [Formula: see text]–composition profiles for the different species in each case indicates that the initial and transition state solvation get more or less compensated and the observed rates are dictated by the increased solvation of H+ in aqueous UH, DMSO, and D co-solvent systems. But in GL–water mixtures the decreased solvation of the transition state compared with the initial state is overcome by the decreased solvation of H+, thus resulting in the gradual enhancement of the rates of the reaction. The observed linearity of the correlative plots of −δ(ΔG≠) [= RT ln (ks/kw)] vs. [Formula: see text] with distinctly different slopes in the two cases also substantiates the relative importance of H+ solvation in dictating the rates of the reaction in these widely different aqueous co-solvents.

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

Benzyl ethers of methyl α-D-glucopyranoside

1980 ◽  
Vol 45 (7) ◽  
pp. 1959-1963 ◽  
Author(s):  
Dušan Joniak ◽  
Božena Košíková ◽  
Ludmila Kosáková
Keyword(s):  
Kinetic Study ◽  
Spectrophotometric Determination ◽  
Reductive Cleavage ◽  
Ether Bond ◽  
Benzyl Ethers ◽  
Acid Catalyzed ◽  
Model Substances ◽  
Hydrolysis Of

Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives. Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

ChemInform Abstract: ACID-CATALYZED HYDROLYSIS OF 3-ALKOXY-4′-SUBSTITUTED CROTONOPHENONES

1979 ◽  
Vol 10 (42) ◽  
Author(s):  
S. D. BRYNES ◽  
L. R. FEDOR
Keyword(s):  
Acid Catalyzed ◽  
Hydrolysis Of

scholarly journals Application of Polyimide‐based Microfluidic Devices on Acid‐catalyzed Hydrolysis of Dimethoxypropane

2021 ◽  
Vol 93 (5) ◽  
pp. 796-801
Author(s):  
Jens Bobers ◽  
Elisabeth Forys ◽  
Bastian Oldach ◽  
Norbert Kockmann
Keyword(s):  
Microfluidic Devices ◽  
Acid Catalyzed ◽  
Hydrolysis Of
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