Acid hydrolysis of acetamide in aqueous acetic acid

1965 ◽  
Vol 18 (6) ◽  
pp. 807 ◽  
Author(s):  
RJL Martin
Keyword(s):  
Acetic Acid ◽  
Reaction Rate ◽  
Ion Pairs ◽  
Bimolecular Reaction ◽  
Aqueous Acetic Acid ◽  
Acid Base ◽  
Wide Range ◽  
Triple Ions ◽  
Association Equilibria ◽  
Hydrolysis Of

The hydrolysis of acetamide in acetic acid has been studied over a wide range of reactant and salt concentrations. The various acid-base and ionic association equilibria must be considered in the interpretation of the data. It is shown that the mechanism is a bimolecular reaction between water and the acetamidium ion and that the acetamidium ion pairs and triple ions have no reactivity. Polar substances such as water and acetamide, apart from undergoing reaction, also increase the reaction rate by favouring the dissociation of the ion pairs. Salts exhibit strong ionic strength and ion-pair effects.

The Kinetics of the Acid Hydrolysis of some Dipeptides in Acetic acid

1957 ◽  
Vol 10 (3) ◽  
pp. 268 ◽  
Author(s):  
RJL Martin
Keyword(s):  
Acetic Acid ◽  
Reaction Rate ◽  
Relative Rate ◽  
Water Concentration ◽  
Aqueous Acetic Acid ◽  
Aminoisobutyric Acid ◽  
Methyl Derivatives ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Bimolecular Mechanism

Glycylglycine and a number of its C-methyl derivatives have been hydrolysed with excess perchloric acid in aqueous acetic acid as solvent, and by varying the water content of the medium its effect on the reaction rate has been determined. It has been found that small changes in the water concentration cause reversals in the relative rate sequences in both series of dipeptides studied. In aqueous acetic acid containing more than 2 per cent. water the relative rate sequence in the first series is glycylglycine > alanylglycine > α-aminoisobutyrylglycine, but at water concentrations less than 2per cent. α-aminoisobutyrylglycine reacts faster than glycylglycine. It is concluded that increasing methylation has produced a change in mechanism whereby α-aminoisobutyrylglycine reacts by a unimolecular heterolysis rather than by the bimolecular mechanism given in the previous paper (Martin 1957). For the second series of dipeptides, the relative rate sequence is glycylglycine > glycylalanine > glycyl-α-aminoisobutyric acid for water concentrations greater than 2 per cent. At water concentrations less than 2 per cent. the rate sequence is reversed, so that glycyl-α-aminoisobutyric acid > glycylalanine > glycylglycine. This reversal is attributed to changes in the polar effect of the terminal carboxyl group which is brought about by increasing methylation.

scholarly journals Perborate Oxidation of Substituted 5-Oxoacids in Aqueous Acetic Acid Medium: A Kinetic and Mechanistic Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Shree Devi ◽  
B. Muthukumaran ◽  
P. Krishnamoorthy
Keyword(s):  
Acetic Acid ◽  
Acid Medium ◽  
Reaction Rate ◽  
Reaction Medium ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Mechanistic Study ◽  
Aqueous Acetic Acid ◽  
Sodium Perborate ◽  
Acetic Acid Medium

Kinetics and mechanism of oxidation of substituted 5-oxoacids by sodium perborate in aqueous acetic acid medium have been studied. The reaction exhibits first order both in [perborate] and [5-oxoacid] and second order in [H+]. Variation in ionic strength has no effect on the reaction rate, while the reaction rates are enhanced on lowering the dielectric constant of the reaction medium. Electron releasing substituents in the aromatic ring accelerate the reaction rate and electron withdrawing substituents retard the reaction. The order of reactivity among the studied 5-oxoacids is p-methoxy ≫ p-methyl > p-phenyl > –H > p-chloro > p-bromo > m-nitro. The oxidation is faster than H2O2 oxidation. The formation of H2BO3+ is the reactive species of perborate in the acid medium. Activation parameters have been evaluated using Arrhenius and Eyring’s plots. A mechanism consistent with the observed kinetic data has been proposed and discussed. Based on the mechanism a suitable rate law is derived.

Spectroscopic analysis of proton exchange during the photocatalytic decomposition of aqueous acetic acid: an isotopic study on the product distribution and reaction rate

2018 ◽  
Vol 8 (22) ◽  
pp. 5886-5899 ◽  
Author(s):  
Saher Hamid ◽  
Ralf Dillert ◽  
Jenny Schneider ◽  
Detlef W. Bahnemann
Keyword(s):  
Carbon Dioxide ◽  
Acetic Acid ◽  
Molecular Hydrogen ◽  
Reaction Rate ◽  
Spectroscopic Analysis ◽  
Product Distribution ◽  
Proton Exchange ◽  
Photocatalytic Decomposition ◽  
Aqueous Acetic Acid ◽  
Isotopic Study

The photocatalytic decomposition of aqueous acetic acid into molecular hydrogen, carbon dioxide, and hydrocarbons employing platinized titania (Pt/TiO2) as a photocatalyst has been studied.

Modeling of Gas Turbine Combustors—A Convenient Reaction Rate Equation

1972 ◽  
Vol 94 (3) ◽  
pp. 173-180 ◽  
Author(s):  
D. Kretschmer ◽  
J. Odgers
Keyword(s):  
Rate Equation ◽  
Reaction Rate ◽  
Reaction Order ◽  
Bimolecular Reaction ◽  
Rate Equations ◽  
Combustion System ◽  
Wide Range ◽  
Simple Mass ◽  
Rich Mixtures ◽  
Reaction Rate Equation

In order to model a practical combustion system successfully, it is necessary to develop one or more reaction rate equations which will describe performance over a wide range of conditions. The equations should be kept as simple as possible and commensurate with the accuracy needed. In this paper a bimolecular reaction is assumed, based upon a simple mass balance. Temperatures derived from the latter are related to measured practical ones such that, if required, an evaluation of the partly burned product composition can be made. A convenient reaction rate equation is given which describes a wide range of blow-out data for spherical reactors at weak mixture conditions. NVP2φ={1.29×1010(m+1)[5(1−yε)]φ[φ−yε]φe−C/(Ti+εΔT)}/{0.082062φyε[5(m+1)+φ+yε]2φ[Ti+εΔT]2φ−0.5} Analysis of the components used in the above equation (especially the variation of activation energy) clearly shows its empirical nature but does not detract from its engineering value. Rich mixtures are considered also, but lack of data precludes a reliable analysis. One of the major results obtained is the variation of the reaction order (n) with equivalence ratio (φ): weak mixtures, n = 2φ; rich mixtures, n = 2/φ. Some support for this variation has been noticed in published literature of other workers.

Compounds of chromium(VI): The pyridine – chromic anhydride complex, benzimidazolinium dichromate, and three 2-alkyl-1H-benzimida -zolinium dichromates

2003 ◽  
Vol 81 (6) ◽  
pp. 612-619 ◽  
Author(s):  
T Stanley Cameron ◽  
Jason AC Clyburne ◽  
Pramod K Dubey ◽  
J Stuart Grossert ◽  
K Ramaiah ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Chromium Trioxide ◽  
Aqueous Acetic Acid ◽  
Secondary Alcohols ◽  
Chromic Anhydride ◽  
Acid Base ◽  
Chromium Vi ◽  
Oxidation Of Alcohols ◽  
Dichromate Anions

Pyridine, when allowed to react with chromic anhydride under strictly anhydrous conditions, gives the known, very air-sensitive, crystalline 2:1 Lewis acid–base complex 1. The crystal structure has now been successfully determined. When benzimidazole and three 2-alkyl-1H-benzimidazoles were treated with chromium trioxide in aqueous acetic acid, crystalline dichromate salts (2–5) were readily formed. These salts consist of dichromate anions linked to the cations by hydrogen bonds of the type N—H···O. The chromium atoms have distorted tetrahedral environments, with the Cr—O distances being typical for dichromate anions. In the cases of the 2-methyl and 2-ethyl salts, the anions are disordered about a centre of inversion. The hydrogen bonding arrangements are discussed and the structures are compared with other oxygenated chromium(VI) species. The dichromate salts are useful selective oxidants for a range of primary and secondary alcohols; examples of these reactions are reported.Key words: chromium(VI), pyridine – chromium trioxide complex, benzimidazolinium dichromate salts, controlled oxidation of alcohols.

scholarly journals Steam Explosion Pretreatment of Beechwood. Part 2: Quantification of Cellulase Inhibitors and Their Effect on Avicel Hydrolysis

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3638
Author(s):  
Simone Brethauer ◽  
Andrzej Antczak ◽  
Robert Balan ◽  
Tomasz Zielenkiewicz ◽  
Michael H. Studer
Keyword(s):  
Acetic Acid ◽  
Enzymatic Hydrolysis ◽  
Steam Explosion ◽  
Biomass Pretreatment ◽  
Reaction Conditions ◽  
Steam Explosion Pretreatment ◽  
Wide Range ◽  
Pretreatment Conditions ◽  
Whole Slurry ◽  
Hydrolysis Of

Biomass pretreatment is a mandatory step for the biochemical conversion of lignocellulose to chemicals. During pretreatment, soluble compounds are released into the prehydrolyzate that inhibit the enzymatic hydrolysis step. In this work, we investigated how the reaction conditions in steam explosion pretreatment of beechwood (severity: 3.0–5.25; temperature: 160–230 °C) influence the resulting amounts of different inhibitors. Furthermore, we quantified the extent of enzyme inhibition during enzymatic hydrolysis of Avicel in the presence of the prehydrolyzates. The amounts of phenolics, HMF, acetic acid and formic acid increased with increasing pretreatment severities and maximal quantities of 21.6, 8.3, 43.7 and 10.9 mg/gbeechwood, respectively, were measured at the highest severity. In contrast, the furfural concentration peaked at a temperature of 200 °C and a severity of 4.75. The presence of the prehydrolyzates in enzymatic hydrolysis of Avicel lowered the glucose yields by 5–26%. Mainly, the amount of phenolics and xylose and xylooligomers contributed to the reduced yield. As the maximal amounts of these two inhibitors can be found at different conditions, a wide range of pretreatment severities led to severely inhibiting prehydrolyzates. This study may provide guidelines when choosing optimal pretreatment conditions for whole slurry enzymatic hydrolysis.

Equilibria in acetic acid: ionic association constant of oxonium perchlorate, acid-base equilibrium constant of oxonium acetate, and autoprotolysisconstant of acetic acid at 105.7°

1965 ◽  
Vol 18 (3) ◽  
pp. 321 ◽  
Author(s):  
RJL Martin
Keyword(s):  
Dielectric Constant ◽  
Acetic Acid ◽  
Equilibrium Constant ◽  
Association Constant ◽  
Ionic Association ◽  
Aqueous Acetic Acid ◽  
Equivalent Conductivity ◽  
Acid Base ◽  
Base Equilibrium ◽  
Acid Base Equilibrium

In aqueous acetic acid, 0.114-0.152M H2O, at 105.7�, oxonium perchlorate has limiting equivalent conductivity Λ0 90.7, ionic association constant KA = [H3O+ClO4-]/[H3O+][ClO4]f2 = 0.0310 x 106 and centre-to-centre distance between the ions (� = 4.84 Ǻ. The acid-base equilibrium constant for oxonium acetate KB = [ΣH3O+ OAc-]/[H2O] increases with the dielectric constant so that -log KB = 1.532+29.44/D. The autoprotolysis of acetic acid also increases with the dielectric constant.

Identification of valence electronic states of aqueous acetic acid in acid–base equilibrium using site-selective X-ray emission spectroscopy

2009 ◽  
Vol 11 (39) ◽  
pp. 8676 ◽  
Author(s):  
Yuka Horikawa ◽  
Takashi Tokushima ◽  
Yoshihisa Harada ◽  
Osamu Takahashi ◽  
Ashish Chainani ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Emission Spectroscopy ◽  
Electronic States ◽  
Aqueous Acetic Acid ◽  
Acid Base ◽  
X Ray ◽  
Base Equilibrium ◽  
Acid Base Equilibrium ◽  
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