Mixture Of Acetic Anhydride Research Articles

C–H Activation: A Versatile Tool for the Synthesis of Niclosamide and Its Derivatives

AbstractA novel strategy has been developed for the direct and regioselective ortho-acetoxylation of N-(2-benzoylphenyl)benzamides through C–H activation using a catalytic amount of Pd(OAc)2 (5 mol%) and a stoichiometric amount of PhI(OAc)2 in a mixture of acetic anhydride and acetic acid. By using this protocol, a new series of niclosamide derivatives was produced in good yields. This is the first report on the synthesis of niclosamide and its derivatives by means of C–H functionalization. This newly developed method offers several advantages such as high regioselectivity, operational simplicity, and good to excellent yields. It provides a short three-step process for the synthesis of niclosamide involving acid–amine coupling, ortho-acetoxylation through C–H activation, and deacylation.

ВОЗМОЖНОСТЬ ИСПОЛЬЗОВАНИЯ ТРИХЛОРУКСУСНОЙ КИСЛОТЫ ДЛЯ АЦЕТОЛИЗА ПЫЛЬЦЕВЫХ ЗЕРЕН ПРИ МЕЛИССОПАЛИНОЛОГИЧЕСКОМ АНАЛИЗЕ

The possibility of using trichloroacetic acid instead of the classical mixture of acetic anhydride with sulfuric acid for acetolysis of pollen grains in the melissopalynological analysis of honey is demonstrated. This substance in comparison with other derivatives of acetic acid allows holding the sample in a boiling water bath that improves the result of acetolysis of pollen grains. The possibility of using various solvents for transferring acetolyzed pollen grains to glass slides for further microscopy was also investigated. The optimal reagents and parameters for this analysis were studied and identified during the experiments.

Preparation and characterization of corn cob cellulose acetate for potential industrial applications

Background: Locally generated biopolymers are amenable to further processing to widen their industrial applications. The study was aimed at generating low-cost cellulose acetate from corn cob residue and its characterizations for potential applications in biopolymer industries. Methods: Cellulose was extracted from the corn cob residue using the sodium hydroxide method. Acetylation of the cellulose to obtain corn cob cellulose acetate was carried out by adding appropriate quantities of a glacial acetic and acetylating mixture of acetic anhydride and sulphuric acid. The corn cob native cellulose and corn cob cellulose acetate were characterized using scanning electron microscopy (SEM) to examine their morphology, Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD) for structural elucidation while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to investigate their thermal properties. Results: - Two corn cellulose acetate samples with degree of substitutions 1.87 and 2.65 for samples CDA and CA respectively were obtained. They had improved solubilities in some organic solvents compared to the corn cob cellulose. The SEM examination showed the surface of the corn cob native cellulose (NC) was smooth and had a regular bundle-like structure while acetylation destroyed the original cellulose structure. Cellulose acetate samples showed a cluster-like structure with different sizes and a rough flake-like surface. FTIR and XRD studies showed that acetyl groups substituted cellulose hydroxyl groups. While FTIR study showed that the cellulose acetates had sharp bands between 1728 cm-1 to 1733 cm-1 and around 1368 cm-1 wavenumber unlike the corn cob cellulose sample, the data generated from XRD study indicated that acetylation of the corn cob cellulose led to 47% and 77% decrease in the crystallinity of CDA and CA samples respectively. The thermal analysis data from DSC and TGA studies confirmed that the acetylation improved the corn cob cellulose's thermal stability as indicated by the degradation of cellulose acetate samples at higher temperatures. Conclusion: The study concluded that low-cost cellulose acetate generated from corn cob residue could be potentially employed as a renewable, biodegradable, biocompatible polymer for industrial applications.

Cluster Compounds with Oxidised, Hexanuclear [Nb6 Cli 12 Ia 6 ]n- Anions (n=2 or 3).

Four mixed‐halide cluster salts with chloride‐iodide‐supported octahedral Nb6 metal atoms cores were prepared and investigated. The cluster anions have the formula [Nb6Cli 12Ia 6] n− with Cl occupying the inner ligand sites and I the outer one. They are one‐ or two‐electron‐oxidized (n=2 or 3) with respect to the starting material cluster. (Ph4P)+ and (PPN)+ function as counter cations. The X‐ray structures reveal a mixed occupation of the outer sites for only one compound, (PPN)3[Nb6Cli 12Ia 5.047(9)Cla 0.953]. All four compounds are obtained in high yield. If in the chemical reactions a mixture of acetic anhydride, CH2Cl2, and trimethylsilyl iodide is used, the resulting acidic conditions lead to form the two‐electron‐oxidised species (n=2) with 14 cluster‐based electrons (CBEs). If only acetic anhydride is used, the 15 CBE species (n=3) is obtained in high yield. Interesting intermolecular bonding is found in (Ph4P)2[Nb6Cli 12Ia 6] ⋅ 4CH2Cl2 with I⋅⋅⋅I halogen bonding and π‐π bonding interactions between the phenyl rings of the cations in (PPN)3[Nb6Cli 12Ia 5.047(9)Cla 0.953]. The solubility of (Ph4P)2[Nb6Cli 12Ia 6] ⋅ 4CH2Cl2 has been determined qualitatively in a variety of solvents, and good solubility in the aprotic solvents CH3CN, THF and CH2Cl2 has been found.

The study of selected properties of pine wood (Pinus sylvestris L.) subjected to acetylation

The study of selected properties of pine wood (Pinus sylvestris L.) subjected to acetylation. In the paper pine wood was subjected to acetylation with acetic anhydride and mixture of acetic anhydride and glacial acetic acid (50:50)v/v. After modification process density, WPG index, water absorbability, volume swelling and colour of wood were carried out and compared with results obtained for unmodified pine wood. Based on the obtained results the density of acetylated pine wood was increased for each group of samples. The highest WPG index was obtained for previously dried wood modified with acetic anhydride (15.6%) or mixture of acetic anhydride and glacial acetic acid (10.5%). Acetylation process with acetic anhydride or mixture of acetic anhydride and glacial acetic acid of samples, which were extracted (in chloroform-ethanol 93:7w/w mixture) and dried before modification, had beneficial effect on water absorbability of pine wood. These samples after 1001h (about 42 days) of soaking in water reached the lowest values of water absorbability (about 94%). Moreover, the volume swelling were significantly reduced for samples after double impregnation cycle (both in case of modification with acetic anhydride or mixture of acetic anhydride and glacial acetic acid). Wood after acetylation process was slightly darker than unmodified pine wood. Acetylation of samples, which were dried and soaked in DMF before modification, caused significant darkening of pine wood. The obtained colour was similar to colour of furfurylated wood (Kebony wood) or some of exotic species.

Selective Acetylation of the Primary Hydroxyl Group in Methyl D-Hexopyranosides with a Mixture of Acetic Anhydride and Acetic Acid

6-O-Acetylated derivatives of D-hexopyranosides are valuable intermediates in synthetic carbohydrate chemistry. We have developed a new simple procedure for selective acetylation of the primary hydroxyl group in methyl D-hexopyranosides consisting in treatment with a mixture of acetic anhydride and acetic acid at 50°C. As a result, corresponding 6-acetates were formed in 40–50% yield.

Synthesis, antimicrobial studies, and molecular docking of some new dihydro-1,3,4-thiadiazole and pyrazole derivatives derived from dithiocarbazates

A series of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles 3a–g, N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl) acetamide derivatives 5a–e and spiro-compound 7 was prepared from starting material dithiocarbazates using N-methylpyrrolidone (NMP) /acetic anhydride mixture. Furthermore, a new series of 5-amino-3- (methylthio) -1-substituted-1H-pyrazole-4-carbonitrile derivatives 12a–d was prepared using two synthetic routes: (i) via reaction of bis (methylthio) methylene malononitrile 8 with carbothiohydrazides 11a–d, or (ii) via reaction of methyl 5-amino-4-cyano-3- (methylthio) -1H-pyrazole-1-carbodithioate 9a with primary/secondary amines. The antimicrobial screening of newly synthesized compounds revealed that compounds 3b, 7, and 12d are the most potent against the Gram-positive (S. aureus) and the Gram-negative (E. coli) bacteria compared to ciprofloxacin as reference drug. Mechanistically, the theoretical docking results of 3b, 7 and 12d suggested that they may act as potent inhibitors of theDNA gyrase.

Comparison of alternative methods for methyl acetate + methanol + acetic acid + acetic anhydride mixture separation

Objectives. The paper is a comparative analysis of methyl acetate + methanol + acetic acid + acetic anhydride industrial mixture separation flowsheets based on the use of special distillation methods (extractive distillation and pressure-swing distillation). The results obtained illustrate the variability of the structure of the technological separation flowsheet.Methods. Mathematical modeling using the software package Aspen Plus V. 10.0 was chosen as the research method. The simulation was based on the local composition equation NRTL and the Hayden–O’Connell equation of state. The relative uncertainties of phase equilibrium description do not exceed 3%.Results. The vapor–liquid diagram of the quaternary mixture of methyl acetate + methanol + acetic acid + acetic anhydride was studied using thermodynamic topological analysis. It was shown that the system contains one binary azeotrope and is characterized by one distillation region. Although the structure is not complex, there is a possibility of using several methods for mixture separation: pressure-swing distillation, and extractive distillation with different entrainers. Twelve flowsheets with different structure were proposed, and 29 variants of separation were compared.Conclusions. It was shown that the most perspective structure for the separation of a methyl acetate + methanol + acetic acid + acetic anhydride mixture is a combination of distributed sequence separation and extractive distillation.

Desulfurization of kraft lignin

Kraft lignin is a product of the sulfate pulping process. It usually contains 2–3% total sulfur. Sulfur content acts as deterrent to lignin use in some areas. Sulfur-free lignins are more versatile and can be heat-treated without the release of foul-smelling sulfur compounds. These lignins are used to produce various low- and high-molecular products, as well as fuel. The existing soft desulfurization methods of kraft lignin allow reducing the total sulfur content, for example, fivefold by a method combining extraction of elemental sulfur, oxidation and reduction in sulfur compounds. Deeper desulfurization has earlier been achieved by catalytic hydrogenation, which is accompanied by depolymerization of lignin. In this paper, it was established that sequential treatment of sulfate lignin with benzene, silver in dimethylformamide, aqueous sodium sulfite solution and perchloric acid + acetic anhydride mixture can reduce the total sulfur content a hundredfold.

Facile Synthesis of Highly Hydrophobic Cellulose Nanoparticles through Post-Esterification Microfluidization

A post-esterification with a high degree of substitution (hDS) mechanical treatment (Pe(hDS)M) approach was used for the production of highly hydrophobic cellulose nanoparticles (CNPs). The process has the advantages of substantially reducing the mechanical energy input for the production of CNPs and avoiding CNP aggregation through drying or solvent exchange. A conventional esterification reaction was carried out using a mixture of acetic anhydride, acetic acid, and concentrated sulfuric acid, but at temperatures of 60–85 °C. The successful hDS esterification of bleached eucalyptus kraft pulp fibers was confirmed by a variety of techniques, such as Fourier transform infrared (FTIR), solid state 13C NMR, X-ray photoelectron spectroscopy (XPS), elemental analyses, and X-ray diffraction (XRD). The CNP morphology and size were examined by atomic force microscopy (AFM) as well as dynamic light scattering. The hydrophobicity of the PeM-CNP was confirmed by the redispersion of freeze-dried CNPs into organic solvents and water contact-angle measurements. Finally, the partial conversion of cellulose I to cellulose II through esterification improved PeM-CNP thermal stability.

Development and validation of a GC–MS method for the determination of hydroxyzine and its active metabolite, cetirizine, in whole blood

A simple, rapid, sensitive and accurate gas chromatography–mass spectrometric method was developed and validated for the simultaneous determination of hydroxyzine and cetirizine in whole blood. Solid-phase extraction procedure using Bond Elut LRC Certify II columns was used for the isolation of hydroxyzine and cetirizine from 1mL whole blood followed by derivatization with a mixture of acetic anhydride:n-propanol (1:1, v/v). Limits of detection and quantification were 1.50 and 5.00ng/mL, respectively. The assay was linear within the concentration range of 5.00–1000.0ng/mL and the correlation coefficient was R2≥0.993 for both analytes. Absolute recovery was determined at three quality control concentration levels and was found to be at least 87.2% for both substances. Intra-day and inter-day accuracy values for both hydroxyzine and cetirizine were ranged from −1.2 to 3.8% and −2.7 to 2.0%, respectively, at the three concentration levels studied, whereas their respective intra-day and inter-day precision values were less than 9.9 and 6.5%, respectively, in terms of relative standard deviation (%RSD). The developed method was successfully applied for the quantification of hydroxyzine and cetirizine concentrations in whole blood, during the investigation of clinical cases where these two antihistamines were detected.

Analysis of Adiabatic Batch Reactor

A mixture of acetic anhydride is reacted with excess water in an adiabatic batch reactor to form an exothermic reaction. The concentration of acetic anhydride and the temperature inside the adiabatic batch reactor are calculated with an initial temperature of 20°C, an initial temperature of 30°C, and with a cooling jacket maintaining the temperature at a constant of 20°C. The graphs of the three different scenarios show that the highest temperatures will cause the reaction to occur faster.

Amidoalkylation of phosphorous acid

A convenient approach to prepare N-protected α-aminophosphonic acids (phospho-isosteres of natural amino acids) via amidoalkylation of phosphorous acid in a mixture of acetic anhydride and acetyl chloride upon cooling has been developed.

Reaction of N-Isopropyl-N-phenyl-2,2′-bipyridin-6-amine with K2PtCl4: Selective C–H Bond Activation, C–N Bond Cleavage, and Selective Acylation

The selective C–H bond activation of N-isopropyl-N-phenyl-2,2′-bipyridin-6-amine promoted by Pt(II) was complicated by the low selectivity of sp2 C–H bond activation in acetonitrile and low yield of sp3 C–H activation in acetic acid. The use of a base was found to effectively suppress the competing sp3 C–H bond activation in acetonitrile, improving the selectivity of sp2 C–H bond activation from 70% to 99%. In the reaction in acetic acid, the low yield was due to the competing C–N bond cleavage. The use of a base reduced the C–N bond cleavage, but not completely. The reaction of N-tert-butyl-N-phenyl-2,2′-bipyridin-6-amine with K2PtCl4 in acetic acid produced the cyclometalated complex with complete C–N bond cleavage and its acylated derivative. These results indicated that the C–N bond cleavage might proceed via heterolytic C–N bond dissociation. The acylation following the C–N cleavage in the reaction in acetic acid is regioselective. Further experiments showed that the reaction of N-phenyl-2,2′-bipyridin-6-amine with K2PtCl4 in acetic acid produced the cyclometalated complex, while the reaction in a mixture of acetic anhydride and acetic acid produced the acylated cyclometalated complex. An X-ray crystal structure study revealed strong intramolecular H bonding in the acylated complexes. The regioselectivity was explained in terms of H bonding and the electron distribution predicted by the DFT calculations.

Palladium-Catalyzed Regioselective ortho-Acetoxylation of 3-Aryl-1,2,4-Benzotriazines via C-H Activation

A highly regioselective <i>ortho</i>-acetoxylation has been achieved in the presence of 10 mol% Pd(OAc)₂ and a stoichiometric amount of PhI(OAc)₂ in a mixture of acetic anhydride and acetic acid via C–H activation to produce the corresponding acetoxy-substituted 3-aryl-1,2,4-benzotriazines derivatives in good yields.

Preparation and Properties of Oligomeric Sulfonated Chitosan

In the homogeneous system, the low molecular weight Chitosan is obtained by H2O2 oxidation degradation method. Acetyl Sulface reacted by the mixture of Acetic Anhydride and Concentrated Sulfuric Acid at equal proportion is the reagent. low molecular weight Chitosan being as raw materials, Vulcanized Oligomer Chitosan is sulfonated with good water-solubility and high sulfur content under certain conditions. It has been tested for the influence of the usage of sulfonated reagent, reaction temperature and reaction time on Sulfer content. The best condition for preparation Vulcanized Oligomer Chitosan is 5ml of Acetyl Sulface with the reaction temperature of 25°C and time of 5 Hours. It’s a new potential heparin with around 100 nm particale size tested by spectral analysis and SEM measurements, which could be a new reagent in other fields.

SYNTHESIS AND POLYMERIZATION OF SOME NEW IMIDES CONTAINING AZO GROUPS OF SULFA DRUGS .

In this work , the synthesis of " four " imides from dehydration of the corresponding amic acids . Sodium acetate – acetic anhydride mixture as dehydrating agent . Then addition azo group in the sulfa drug compounds to this imides resulted (16) new monomers . Free radical polymerization using AIBN initiator have done to all new obtained monomers containing azo – sulfa . The resulted (16) new polymers , were characterized with IR , softening points and intrinsic viscosities .

Regioselective ortho-acetoxylation/methoxylation of N-(2-benzoylphenyl)benzamides via substrate directed C–H activation

A highly regioselective ortho-acetoxylation of N-(2-benzoylphenyl)benzamides has been achieved using a catalytic amount of Pd(OAc) 2 (10 mol %) and a stoichiometric amount of PhI(OAc) 2 in a mixture of acetic anhydride and acetic acid via C–H activation to produce the corresponding 2-acetoxybenzamides in good yields. ortho-Methoxylation has been accomplished using methanol under similar conditions.

Amidoalkylation of hydrophosphoryl compounds

A new mild procedure of the amidoalkylation of hydrophosphoryl compounds in a mixture of acetic anhydride and acetyl chloride was developed as a convenient method of constructing the α-aminophosphoryl fragment of the pseudo-α,α′-dipeptide molecule. The reaction intermediates N,N′-benzylidene- and N,N′-alkylidenebiscarbamates were detected, isolated, and identified. The report presents the results of studying the direct interaction of hydrophosphoryl compounds previously synthesized with biscarbamates in acetic anhydride and other solvents, the influence of the structure of phosphorus component and biscarbamate, and the effect of acid catalysis on the course of this two-component reaction. A new version of the mechanism of the three-component reaction of amidoalkylation of hydrophosphoryl compounds is suggested: it is regarded as a multistage process involving the stage of biscarbamate formation followed by the stage of Arbuzov-type reaction with the intermediate formation of acyliminium cation and P-OAc derivative with trivalent phosphorus.

Preparation and characterization of ternary copolyimide fibers via partly imidized method

A series of copolyamic acid (PAA) were synthesized from various ratios of two diamines p-phenylene diamine and 4,4′-oxydianiline (ODA) via copolymerization with pyromellitic dianhydride (PMDA) in polar solvent dimethylacetamide. A mixture of acetic anhydride and triethylamine was used as the cyclizing agent and added to the PAA in order to chemically convert it into partly imidized PAA, which then was spun into fibers by dry-jet wet-spinning. Finally, polyimide (PI) fibers were prepared after the as-spun fibers had been heat-treated. The results indicated that the intrinsic viscosity of partly imidized PAA was higher than that of pure PAA. Moreover, when the partly imidized PAA was spun into a suitable composition coagulation bath, the as-spun fibers gained a circular and dense internal morphology. The tensile strength and initial modulus of the heat-treated PI fibers were better than those of the homo-PI PMDA-ODA fibers, respectively, and the thermal stability of the PI fibers was also enhanced.