Aqueous Acetic Acid Medium Research Articles

Kinetic Study of Oxidation of Thiophene-2-Carbaldehyde by Imidazolium Dichromate Promoted By 1, 10-Phenanthroline

Kinetic study of oxidation of Thiophene-2-carbaldehyde by Imidazolium dichromate in aqueous acetic acid medium using 1,10-phenanthroline have been studied. In the absence of mineral acids, the oxidation kinetics of Thiophene-2-carbaldehyde acid by Imidazolium dichromate shows a first-order dependence on Imidazolium dichromate and fractional order on Thiophene-2-carbaldehyde. The variation of ionic strength, H+ and reaction product have in significant effect on reaction rate. Activation parameters have been studied for the reaction from the Arrhenius plot by studying the reaction at different temperatures.

Insight into D-galactose Oxidation: Kinetic and Mechanistic Analysis with Imidazolium Fluorochromate

In a 50% (v/v) aqueous acetic acid medium, a study on the oxidation kinetics of D-galactose by imidazolium fluorochromate (IFC) was conducted. The study revealed unit-order dependence on [D-galactose], [IFC], and [perchloric Acid]. The reaction was catalyzed by perchloric acid, and followed a 1:1 stoichiometric ratio. Adding sodium hyperchlorate (VII) salt did not affect the reaction. Polymerization of acrylonitrile was not observed in the oxidation process. The oxidation rates were retarded on adding Mn2+ ions in the mixture, and rates increased as the reaction medium’s dielectric constant (D) decreased. The observed results follow the Amis and Kirkwood plots {log k1 vs. (1/D) and ((D-1/2D+1))}. Several thermodynamic variables were determined by analyzing the kinetic data across a temperature range. Arabinose and formic acid were formed as the products of the reaction. A mechanistic path involving the formation of an ester followed by hydride ion transfer was proposed.

Oxidation of D-Glucose and D-Fructose by N-Bromosaccharin in Aqueous Acetic Acid Medium in Presence of NaLS: A Comparative Study

The oxidation of D-Glucose and D-Fructose was monitored iodometrically by N-Bromosaccharin in the aqueous acetic acid medium in presence of NaLS (Sodium Lauryl Sulphate). Reaction demonstrated that oxidative species HOBr and H2O⊕Br were involved in the acidic oxidation of Carbohydrates. It was established that respective acids of carbohydrates gluconic acid and arabinoic acid were the oxidation products. Respective acids of carbohydrates were the results of reactive HOBr in acidic conditions. The reaction follows first-order kinetics with respect to HOBr, Glucose, Fructose, and [H+] uniformly and is homogeneous. The Effect of varying salt electrolyte concentration was insignificant showing that the molecular species was involved in the rate-determining step. The Reaction was monitored at 600C (±10C) temperature and thermodynamic activation parameters were determined. Binding parameters have been calculated by analyzing the data using the model suggested by Menger Portnoy and Piszkiwicz's model. Kinetic studies, stoichiometry of the reaction and product analysis have been proposed for the oxidation of sugars in the presence of NaLS.

Oxidation of Perfumery Secondary Alcohols by Nicotinium Dichromate; A Kinetic Study

Chemical kinetics is mainly concerned with studying the factors that change the reaction rate and the response mechanism. The present paper investigates the rate law for the reaction, order of the reaction of secondary alcohols(menthol) and compares it to other secondary alcohols like Borneol and Isoborneol. Diagnose the product of the oxidation reaction. The kinetics of oxidation of perfumery secondary alcohols [menthol], [Borneol], and [Isoborneol] by NDC have been studied in the aqueous acetic acid medium at 303K. The secondary perfumery alcohols were converted to the corresponding carbonyl compounds. The order concerning [Subs], [Oxi], and [H+] ions concentration is found to be one. The decrease in the dielectric constant of the medium enhances the rate of the reaction. The ionic strength of the medium has no significant effect on the reactivity of the response; it does not induce the polymerization of Acrylonitrile, indicating the absence of free radical pathway. The added Mn2+ ions show the reaction rate was slightly increasing order. The reaction has been studied at four different temperatures Eyring equation is used to calculate the thermodynamic parameters like Gibbs free energy change (ΔG#), entropy change (ΔS#), and enthalpy change (ΔH#). On increase in the temperature of the reaction, the rate of reaction increased abruptly. There was a decrease in entropy (ΔS#) of the system indicated by the value of entropy which showed some restriction in the freedom movement of the molecules. It was observed that the reactivity follows Menthol<Isoborneol<Borneol. Based on steric factors, structure, and isomeric characteristics of the alcohols under investigation.

Electrochemical Hydrogenation of Furfural in Aqueous Acetic Acid Media with Enhanced 2-Methylfuran Selectivity Using CuPd Bimetallic Catalysts.

Herein, we report a series of CuPd catalysts for electrochemical hydrogenation (ECH) of furfural to 2-methylfuran (MF or FurCH3 where Fur=furyl) in aqueous 0.1 M acetic acid (pH 2.9). The highest faradaic efficiency (FE) for MF reached 75 % at -0.58 V vs. reversible hydrogen electrode with an average partial current density of 4.5 mA cm-2 . In situ surface-enhanced Raman spectroscopic and kinetic isotopic experiments suggested that electrogenerated adsorbed hydrogen (Hads ) was involved in the reaction and incorporation of Pd enhanced the surface coverage of Hads and optimized the adsorption pattern of furfural, leading to a higher FE for MF. Density functional theory calculations revealed that Pd incorporation reduced the energy barrier for the hydrogenation of FurCH2 * to FurCH3 *. Our study demonstrates that catalyst surface structure/composition plays a crucial role in determining the selectivity in ECH and provides a new strategy for designing advanced catalysts for ECH of bio-derived oxygenates.

OXIDATION OF VANILLIN BY IODATE IN AQUEOUS ACETIC ACID MEDIUM: A KINETIC AND MECHANISTIC STUDY

The kinetics and mechanism of the oxidation of vanillin by iodate in aqueous acetic acid medium is studied. The reaction exhibits first order in [Iodate], fractional order in [vanillin] and [acid]. Variation of ionic strength had no effect on the reaction rate. Increase in the reaction rate by a decrease in the dielectric constant of the medium is observed. The reaction was studied at four different temperatures and the related activation and thermodynamic parameters were calculated. The product of oxidation was confirmed as vanillic acid by spectral analysis. Based on the results a plausible mechanism has been proposed and the appropriate rate law has been derived.

Study of oxidation of dyes by N-chlorosuccinimide in aqueous acetic acid medium: A kinetic and mechanistic

Kinetics of oxidation of Dyes by N-Chlorosuccinamide(NCS) in acetic acid medium has been done in the presence of hydrochloric acid. The reaction follows first order kinetics with respect to both [NCS], [Substrate] and [HCl]. Increases in ionic strength increases the rate and addition of the reaction product succinamide has a slight retarding effect on the reaction rate. Increase in the dielectric constant of the medium decreases the rate. Activation parameters have been evaluated from Arrhenius plot by studying the reaction at different temperature [40-55 oC] and oxidation products are identified. A most probable reaction mechanism is proposed and an appropriate rate law is deduced to account for the observed kinetic data.

Kinetics and mechanistic study of oxidation of α-amino acid leucine by TCICA in aqueous acetic acid medium

Kinetics and mechanistic study of oxidation of α-amino acid leucine by TCICA in aqueous acetic acid medium

Direct ionization and solubility of chitosan in aqueous solutions with acetic acid

A better understanding of the physicochemical phenomena underlying the direct solubilization of solid chitosan in an aqueous acetic acid medium without the addition of salt is needed. These phenomena have been studied using an inverse approach in which the chitosan is treated as a poly-acid and not as poly-base, and the macrophenomenon observed represents the aggregation of the macromolecules of chitosan instead of their solubilization. The purpose of this study is to present an overview of the physicochemical phenomena underlying this direct solubilization in an aqueous acetic acid medium without the addition of salt through a mathematical model based on equilibrium equations, mass balances, and correlations between experimental data. This model allowed us to model dilute chitosan/acetic acid/water systems without the addition of salt with an adequate fit (R2 > 0.9951) to the trend of the experimental data, enabling the calculation of the pH, degree of ionization, apparent dissociation constant, and the concentrations of the smaller molecules $$\left( {{\text{CH}}_{3} {\text{COOH}}, {\text{CH}}_{3} {\text{COO}}^{ - } ,{\text{H}}_{3} {\text{O}}^{ + } } \right)$$ , with only a priori knowledge of the initial concentration of acetic acid, initial concentration of amine groups, and the dissociation constant of acetic acid. The main finding of this study was that the diluted systems lacking salt studied here showed a tendency toward an apparent dissociation constant of $$pK_{1/2} \to 6.44$$ as the polymer concentration increased. This value is similar to the values reported in the literature for systems containing salt and a degree of deacetylation $$\left( {f_{\text{D}} \sim 0.7} \right)$$ similar to the chitosan evaluated here.

Synthesis of Novel 1‐(5‐(Benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea Derivatives and Evaluation of Their Antimicrobial Activities

A new series of 1‐(5‐(benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea derivatives (1a–j) were designed and synthesized. For the first time, (i) a new process was developed for N‐methylation of 1,3,4‐thiadiazole moiety using dimethyl carbonate an environmentally benign reagent in presence of N,N,N′,N′‐tetramethylethylenediamine and (ii) the sulfide was selectively oxidized to sulfoxide in higher yield by using chlorine (g) in aqueous acetic acid media under mild reaction condition. The synthesized compounds (1a–j) were investigated for their antimicrobial activities. The tested compounds (1a–j) were exhibited moderate to excellent antibacterial activities against both Gram‐positive and Gram‐negative bacterial strains. The same compounds exhibited good antifungal activities against selected fungal strains. Particularly, the compounds 1b, 1d, 1h, and 1i were proved to be promising leads exhibiting both antibacterial and antifungal activities compared with standard drugs, ciprofloxacin, and fluconazole. The presence of 1,3,4‐thiadiazole moiety has a significant role in the display of antimicrobial activity. In addition, the presence of both sulfinyl and thiourea or urea functionalities has enhanced the activity as per obtained antimicrobial activity data.

TELLUROCYCLISATION OF CONDENSED N-ALKENYL DERIVATIVE 4-OXOPYRYMIDINE-2-TION

The derivatives of quinazolines and their fused analogues are promising objects for the rational design of biologically active compounds as prototypes for innovative medicines. This is due to the fact that the quinazoline fragment is a structural unit of many natural alkaloids. Electrophilic intramolecular heterocyclization is a promising method for the synthesis of fused derivatives of quinazoline.This research is devoted to the synthesis of new functionalized unsaturated condensed derivatives of quinazolin-4-one and the study of the regio chemistry of the process of electrophilic heterocyclization under the action of tellurium tetrachloride. The choice of such an electrophilic reagent is due to the fact that in recent years the organic synthesis of chalcogen-containing compounds, in particular, tellurium compounds that exhibit a wide range of biological activity, is increasingly developing.It was established that the electrophilic intramolecular cyclization of 3-alkenyl-2-thioquinazolin-4-one under the action of tellurium tetrachloride in an aqueous acetic acid medium at room temperature takes place with the participation of the alkenyl moiety and the exocyclic sulfur atom in the second position of quinazoline. As a result, thiazolidinequinazoline systems of linear structure were obtained. The structure and composition of the obtained tellurium-containing hydrochlorides has been proved by 1H, 13C NMR spectra and elemental analysis. In the PMR spectrum of hydrochlorides, signals of aliphatic cyclic methylene and methine groups and of the acyclic trichlorotellanylmethyl group are observed, which, together with the signals of aromatic protons, indicates on the formation of thiazolidinequinazolones. The absence of signals characteristic of the C=S group and presence of signals typical for the C-S bond in the 13C NMR spectra are in accord with the proposed structure of the cyclization products.Thus, we investigated the regio chemistry of the electrophilic intramolecular cyclization of 3-alkenyl-2-thioquinazolin-4-one under the action of tellurium tetrachloride. It was proved that the annelation of the thiazolidine cycle takes place with the participation of the sulfur atom in the second position of the pyrimidine, with the formation of tricyclic hydrochlorides of linear structure.

Synthesis, kinetics, and mechanism of bromophenols by N‐bromophthalimide in aqueous acetic acid

AbstractThe kinetics and mechanism of bromination of phenol and its substituents, viz. 4‐chlorophenol, 4‐bromophenol, 4‐methylphenol, and 4‐methoxyphenol by N‐bromophthalimide (NBP) in the presence of mercuric acetate in the temperature range of 303–318 K in aqueous acetic acid medium have been investigated. The reaction follows first‐order dependence on [NBP] and fractional order dependence of rate on [Phenol]. The activation parameters have been evaluated, and based on the observed kinetic results the probable mechanism has been proposed. Observed kinetic features and Hammett's reaction constant (ρ) suggests that bromination occurs through electrophilic substitution of bromonium ion (Br+) into the aromatic ring in the transition state. Large negative entropy of activation values probably suggests the rigid nature of transition state.

2-Nitrobenzaldehyde Thiocarbohydrazone Assisted Precise Extraction Spectrophotometric Method for the Determination of Ruthenium(III) in Alloy and Catalysts

A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)‒2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1‒6 g/mL of ruthenium(III), the optimum concentration range was 2‒5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 104 L/mol/cm and 0.0075 μg/cm2, respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.

Kinetics and Mechanistic study of oxidation of L-Alanine by Using N-Bromophalimide in presence of Chloro-Complex of Pd (II) as Homogenous Catalyst in Aqueous Acetic acid medium

Kinetics and Mechanistic study of oxidation of L-Alanine by Using N-Bromophalimide in presence of Chloro-Complex of Pd (II) as Homogenous Catalyst in Aqueous Acetic acid medium

Study on Catalysed Oxidation of Some Aliphatic Hydroxy Acids by N-chlorosuccinimide in Aqueous Acetic Acid Medium

Study on Catalysed Oxidation of Some Aliphatic Hydroxy Acids by N-chlorosuccinimide in Aqueous Acetic Acid Medium

Kinetics and Mechanistic Oxidation of ℓ-Leucine and ℓ-Valine by 1,3-Dichloro-5,5-dimethylhydantoin in Aqueous Acetic Acid Medium

Kinetics and Mechanistic Oxidation of ℓ-Leucine and ℓ-Valine by 1,3-Dichloro-5,5-dimethylhydantoin in Aqueous Acetic Acid Medium

Kinetics and Thermodynamics of Oxidation of Some para-Substituted 4-Oxo-4-phenyl Butanoic Acids by Tripropylammonium Fluorochromate in Aqueous Acetic Acid Medium

Kinetics and Thermodynamics of Oxidation of Some para-Substituted 4-Oxo-4-phenyl Butanoic Acids by Tripropylammonium Fluorochromate in Aqueous Acetic Acid Medium

Study on Effect of Cuso4 and Mnso4 on the Reaction Rate of Substituted Alcohols by N-Bromophthalimide in Aqueous Acetic Acid Medium

Study on Effect of Cuso4 and Mnso4 on the Reaction Rate of Substituted Alcohols by N-Bromophthalimide in Aqueous Acetic Acid Medium

Kinetics and mechanism of oxidation of some heterocyclic aldehydes by benzimidazolium fluorochromate in aqueous acetic acid medium

Kinetics and mechanism of oxidation of some heterocyclic aldehydes by benzimidazolium fluorochromate in aqueous acetic acid medium

Kinetics and Mechanism of Oxidation of 4-Oxo-4-phenylbutanoic Acid by N-Bromoanisamide in Aqueous Acetic Acid Medium

Kinetics and Mechanism of Oxidation of 4-Oxo-4-phenylbutanoic Acid by N-Bromoanisamide in Aqueous Acetic Acid Medium