Excess Of Carboxylic Acid Research Articles

Исследование и получение соединений карбоновых кислот из смол узгенских углей

In the article, sodium acetate was studied and obtained from carboxylic acids from coal tar of brown coal by the method of neutralization and drying and crystallization were made. Investigated and obtained ethyl acetate from carboxylic acids from the resin of Uzgen brown coal, by the esterification method and by the low-temperature distillation method. Excess carboxylic acids and azeotropic substances were checked, repeated purification was done, and pure ethyl acetate was obtained at a temperature of 77–78 °C.

Long-Range Ferromagnetic Exchange Interactions Mediated by Mn-CeIV-Mn Superexchange Involving Empty 4f Orbitals.

Reactions involving reductive aggregation of MnO4- in methanol in the presence of CeIV and an excess of carboxylic acid have led to the synthesis of structurally related Ce/Mn clusters, [Ce3Mn5O8(OMe)(O2CBut)13(MeOH)] (1) and [Ce2Mn3O5(O2CPh)9(MeOH)3] (2), containing at least one {Mn2Ce2O4} cubane unit. The cores of both clusters contain Mnx units separated by three (1) or two (2) CeIV ions. Fits of variable-temperature, solid-state dc and ac magnetic susceptibility data reveal dominant ferromagnetic interactions within 1 and 2, resulting in the maximum S = 17/2 and S = 5 ground state spins, respectively, and thus suggesting significant ferromagnetic (F) interactions between the Mnx units that are ≥6 Å apart and separated by four intervening bonds through diamagnetic CeIV. Fits of magnetic susceptibility data also revealed unusual long-range F interactions, and this finding was further supported by high-field EPR measurements and simulations. Density functional theory calculations and a Wannier function analysis confirm long-range interactions and indicate a Mn-Ce-Mn superexchange pathway via Mn-d/Ce-f orbital overlap/hybridization.

Functionalized Graphene Oxide Bridging between Enzyme and Au-Sputtered Screen-Printed Interface for Glucose Detection

This work reports the fabrication of an electrochemical glucose biosensor based on functionalized graphene, assembled onto a gold-sputtered screen-printed electrode. With the aim of simplicity, versatility, and low cost, biosensors dually functionalized with graphene oxide containing excess carboxylic acids and thiol functionality were synthesized and characterized by Fourier transform infrared, Raman, and UV–vis spectroscopy. The increased carboxylic groups of the graphene backbone provided more active sites for the remote functional groups of glucose oxidase during 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide-assisted immobilization. The modified electrode interface was characterized by scanning electron microscopy, atomic force microscopy, and cyclic voltammetry. This hybrid electrode interface showed higher sensitivity for glucose (3.1732 μA mM–1 cm–2) with a detection limit of 0.3194 mM (S/N = 3). Furthermore, the fabricated biosensor demonstrated a linear response in 3–9 mM glucose concentration ...

A convenient stereoselective access to novel 1,2,4-triazepan-3-ones/thiones via reduction or reductive alkylation of 7-membered cyclic semicarbazones and thiosemicarbazones.

A general stereoselective approach to previously unknown 1,2,4-triazepane-3-thiones/ones based on reduction or reductive alkylation of readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones has been developed. The approach involved the treatment of tetrahydrotriazepines with sodium cyanoborohydride in MeOH at pH 3 or with sodium borohydride and excess of carboxylic acid in THF to give 1-unsubstituted or 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones, respectively. The latter were also prepared by the reaction of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones with sodium cyanoborohydride and an aldehyde in MeOH in the presence of AcOH. The stereochemistry of the triazepane-3-thiones/ones obtained was established in DMSO solution and in the solid state using NMR spectroscopy and single-crystal X-ray diffraction. These data and DFT B3LYP/6-311++G(d,p) calculations show that the gauche effect plays a significant role in stabilization of preferred conformations of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones.

Impact of dissolved and undissolved organics on foaming of industrial amine

The effect of soluble and insoluble organics i.e. liquid paraffin, carboxylic acids, and BTEX on foaming behavior of industrial fresh and lean amine solution was investigated. Different fresh and lean amine samples were saturated with different organics through mixing the amine solution with the organics in thermodynamic cell until equilibrium. Saturated amine samples were extracted from the equilibrium cell and foaming study was carried out for each saturated amine solution. The effect of insoluble organics on the amine foaming behavior was tested through adding excess organics to the saturated amine. The results of this study showed that dissolved organics increased the foam volume in fresh 50wt% MDEA solution. However, adding excess organics, above the solubility limit, into the fresh amine decreased the foam volume. Interestingly, saturated industrial lean amine with normal liquid paraffin (C6–C7) decreased the foam volume of the industrial lean amine. Moreover, the foaming tendency decreased significantly when the concentration of normal liquid paraffin exceeded the solubility limit in the tested lean amine solution. It is noted that cyclohexane has more influence in amine foaming than n-hexane. Saturated industrial lean amine solution with carboxylic acids dramatically increased the foam volume. Adding excess carboxylic acids above the solubility limit decreased the foam volume of the saturated amine, however, it remains higher than the foam volume of the original lean amine. Soluble toluene and xylene increased the foam volume from 120ml to 647ml and 471ml, respectively. Adding excess BTEX over the solubility limit to the saturated lean amine reduced the foaming tendency of the saturated amine. However, as observed with the carboxylic acids the foam volume with excess BTEX still showing higher volume over the original lean amine. The findings of this study highlight the importance of controlling the concentration of BTEX compound entering to the amine unit over the liquid hydrocarbons as a common foaming mitigation practice. Also, the findings of this study highlight the importance of monitoring the generation of carboxylic acids due to amine degradation and control its concentrations for smoother operation.

ChemInform Abstract: Palladium‐Catalyzed Aerobic Aminooxygenation of Alkenes for Preparation of Isoindolinones.

AbstractA series of functionalized alkenes is treated with excess carboxylic acid including amino acids (X) in the presence of molecular oxygen under conditions A) (oxidation mechanism).

Carboxylation and Decarboxylation of Aluminum Oxide Nanoparticles Using Bifunctional Carboxylic Acids and Octylamine

The carboxylation of alumina nanoparticles (NPs), with bifunctional carboxylic acids, provides molecular anchors that are used for building more complexed structures via either physisorption or chemisorption. Colloidal suspensions of the NPs may be prepared by covalently bonding a series of carboxylic acids with secondary functional groups (HO2C-R-X) to the surface of the NPs: lysine (X = NH2),p-hydroxybenzoic acid (X = OH), fumaric acid (X = CO2H), and 4-formylbenzoic acid (X = C(O)H). Subsequent reaction with octylamine at either 25°C or 70°C was investigated. Fourier transform IR-attenuated reflectance spectroscopy (FTIR-ATR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) along with energy dispersive X-ray (EDX) analysis were used to characterize the bifunctionalized monolayers and/or multilayer corona surrounding the alumina NPs and investigate the reaction mechanism of octylamine with the functional groups (X) of the NPs. Except for the fumaric functionalized NPs, addition of octylamine to the functionalized NPs leads to removal of excess carboxylic acid corona from the surface via an amide formation. The extent of the multilayer is dependent on the strength of the acid⋯acid interaction.

Microwave-Assisted Esterification: A Discovery-Based Microscale Laboratory Experiment

An undergraduate organic chemistry laboratory experiment has been developed that features a discovery-based microscale Fischer esterification utilizing a microwave reactor. Students individually synthesize a unique ester from known sets of alcohols and carboxylic acids. Each student identifies the best reaction conditions given their particular reagents (either excess alcohol or excess carboxylic acid) as well as the ideal workup procedure for their reaction. Products are analyzed using 1H NMR spectroscopy, IR spectroscopy, and scent. This modern adaptation of the classic Fischer esterification provides the opportunity for discussion of important chemistry concepts, including acid catalysis, Le Châtelier’s principle, and green chemistry.

Facile One-Pot Synthesis of Triphenylbismuth(V) Bis(carboxylate) Complexes

Triphenylbismuth(V) bis(carboxylates), Ph3Bi(O2CR)2 (R = 5-Br-2-OH-C6H3 (1), 2-OH-C6H4 (2), 2,6-(OH)2-C6H3 (3), 3-Me-2-NH2-C6H3 (4), Ph (5), Me (6)), were obtained from the reaction of triphenylbismuth with hydrogen peroxide and excess carboxylic acid in wet 2-propanol. The synthesis avoids the use of halogens as oxidants, and the products crystallize directly from the solution as pure compounds. They crystallize from solution without further need for purification. The structures of 1–5 were confirmed by single-crystal X-ray diffraction. Compounds 2 and 5 exhibit a polymorph different from that previously reported in the literature. While all of the Bi(V) compounds adopt a trans-axial trigonal-bipyramidal configuration with the carboxylates in axial positions, there is considerable variation in the coordination of the carboxylate that ranges from simple η1 to a mixture of mono- and bidentate chelating bonding modes.

Thermal analysis and FTIR studies of volatile corrosion inhibitor model systems

Abstract Model compounds simulating amine–carboxylic acid-based volatile corrosion inhibitors were characterized by thermogravimetric analysis and Fourier transform infrared spectroscopy. These systems are usually employed as equimolar mixtures to protect ferrous metals against atmospheric corrosion. The key finding of this study was that the vapors released by such equimolar mixtures initially contain almost free amine only. After prolonged vaporization a steady-state azeotrope-like composition is approached. It contains excess carboxylic acid and features impaired corrosion inhibition efficiency according to the Skinner test. In part, this behavior can be attributed to the mismatch in the volatilities of the amine and carboxylic acid constituents.

Ionic liquids as solvent for efficient esterification of carboxylic acids with alkyl halides

Esterification of carboxylic acids is one of the most important reactions in organic synthesis, and more environmentally benign alternative approaches to those currently used by the chemical industry are in great demand. Conventional esterification is conducted with excess carboxylic acids (or alcohols) against a counterpart in the presence of an acid catalyst, or with stoichiometric dehydrating reagents or activated carboxylic acid derivatives. The use of excess substrates wastes these compounds, and the use of stoichiometric dehydrating reagents or activated carboxylic acid derivatives produces significant amounts of byproducts from the reagents. Salts of the carboxylic acids may also be converted into esters by heating them with alkyl halides. This reaction is most successful with primary halides, but secondary and tertiary halides given ester with olefin as a byproduct by loss of hydrogen halide from the alkyl halide. The contamination of crude products with excess substrates or byproducts requires substantial materials, energy, and time for the purification of ester. Recently, efforts ∗Corresponding author

An asymmetric synthesis of carboxylic acid derivatives, including lactic acid and α-amino acid derivatives, from optically active 1-chlorovinyl p-tolyl sulfoxides and ester lithium enolates with creation of chirality at the α-position

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones or methyl formate and ( R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent (alkyl, alkoxy, or dibenzylamino group) at the α-position with high 1,4-chiral induction from the sulfur chiral center. The adducts were converted to optically active esters, lactic acid, and α-amino acid derivatives having a chiral center at the α-position. When this addition reaction was carried out with an ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolate, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, ( R)-(−)-chloromethyl p-tolyl sulfoxide, was achieved.

Hydrolysis of Acyloxy Nitroso Compounds Yields Nitroxyl (HNO)

Nitroxyl (HNO/NO(-)), the reduced form of nitric oxide, has gained attention based on its separate chemistry and biology from nitric oxide. The inherent reactivity of HNO requires new and mechanistically unique donors for the detailed study of HNO chemistry and biology. Oxidation of cyclohexanone oxime with lead tetraacetate yields 1-nitrosocyclohexyl acetate, whereas oxidation of oximes in the presence of excess carboxylic acid gives various acyloxy nitroso compounds. These bright blue compounds exist as monomers as indicated by their infrared, proton, and carbon NMR spectra, and X-ray crystallographic analysis reveals the nitroso groups possess a "nitroxyl-like" bent configuration. Hydrolysis of these compounds produces nitrous oxide, the dimerization and dehydration product of HNO, and provides evidence for the intermediacy of HNO. Both thiols and oxidative metal complexes inhibit nitrous oxide formation. Hydrolysis of these compounds in the presence of ferric heme complexes forms ferrous nitrosyl complexes providing further evidence for the intermediacy of HNO. Kinetic analysis shows that the rate of hydrolysis depends on pH and the structure of the acyl group of the acyloxy nitroso compound. These compounds relax pre-constricted rat aortic rings similar to known HNO donors. Together, these results identify acyloxy nitroso compounds as a new class of HNO donors.

A novel method for asymmetric synthesis of both enantiomers of α-substituted carboxylic acid derivatives from optically active 1-chlorovinyl p-tolyl sulfoxides and lithium ester enolates with 1,4-chiral induction from the sulfur chiral center

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones and ( R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent at the α-position with high 1,4-chiral induction from the sulfur chiral center in high yields. The adducts were converted to optically active esters and carboxylic acids having a chiral center at the α-position. When this addition reaction was carried out with the ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolates, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, ( R)-(−)-chloromethyl p-tolyl sulfoxide, was realized.

Synthesis and characterization of novel tricarboxylatoplatinum(IV) complexes. Nucleophilic substitution of (diamine)-tetrahydroxoplatinum(IV) with carboxylic acid

The reaction of [Pt(IV)(dach)(OH) 4] (dach= trans-(±)-1,2-diaminocyclohexane) with an excess of carboxylic acid at room temperature afforded tricarboxylatoplatinum(IV) complexes, [Pt(dach)(L) 3(OH)] (L=acetato, propionato, valerato) in contrast to the carboxylation reaction with excess carboxylic anhydrides, which gave only tetracarboxylatoplatinum(IV) complexes as a major product. The protonation on hydroxo ligand of the platinum(IV) complex to form aqua ligand seems to be followed by nucleophilic substitution by carboxylate or chloride anion. Such nucleophilic substitution afforded only partially substituted tricarboxylatoplatinum(IV) complexes in carboxylic acid solvent whereas the reaction in 0.1 M HCl solution gave tetrachloroplatinum(IV) complex. This difference is explainable by different p K a values of the four aqua ligands, among which the last aqua ligand may have sufficiently low p K a value allowing the protonation only in strong acidic media like hydrochloric acid.

Facile radiolabelling and purification of 2β‐[O‐11CH3]‐carbomethoxy‐3β‐aryltropanes: Radiotracers for the dopamine transporter

AbstractTwo potent dopamine transporter ligands, 2β‐[O‐11CH3]‐carbomethoxy‐3β‐(4‐methylphenyl)tropane and its 4‐chlorophenyl analogue, were synthesized by O‐alkylation at the 2β‐carboxy position with [11C]‐iodomethane. Separation of the [11C]‐labelled tropane from excess carboxylic acid precursor was readily achieved by semipreparative HPLC providing pure radiotracers at high specific activities (800–3000 mCi/μmole) suitable for in vivo PET studies. Radiosynthesis of this class of compounds by [O‐11CH3]‐methylation offers advantages over previously reported [N‐11CH3]‐methylation methods.

ChemInform Abstract: Anodic Oxidation of Active Methylene Groups in the Presence of Excess Carboxylic Acid.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Anodic Oxidation of Active Methylene Groups in the Presence of Excess Carboxylic Acid

Abstract The anodic oxidation of anthrone, (9,(10H)-anthracenone), 9,10-dihydroanthracene and 1-tetralone in acetonitrile was studied under the presence of excess carboxylic acids. The oxidation of anthrone with acetic acid gave anthraquinone, 10-acetoxyanthrone and 10-methyl-10-acetoxyanthrone. A similar reaction of anthrone with propionic acid yielded 10-propionyloxyanthrone. The electronic oxidation of 9,10-dihydroanthracene yielded anthraquinone, anthrone, and 9-acetoxyanthrone under the same conditions. Also, 1-tetralone reacted with acetic acid and propionic acid at the 4 position of the carbonyl group, giving 4-acetoxy- and 4-propionyloxy-1-tetralone, respectively.

From Minierals to Materlals: A Facile Synthetic Route to Preceraic Polymers for Aluminum Oxide

ABSTRACTReaction of boehmite, [AI(O)(OH)]n, with an excess of carboxylic acid (HO2CR) results in the formation of the carboxy substituted alumoxanes, [AI(O)x(OH)y(O2CR)z)]n where 2x + y + z = 3 and R = alkyl substituents. The alumoxanes have been fully characterized by SEM, elemental analysis, IR and multinuclear NMR spectroscopy. The physical properties of the alumoxanes are highly dependent on the identity of R, and range from insoluble crystalline powders, e.g. R = CH3, to powders which readily form solutions or gels in hydrocarbon solvents, e.g. R = C5H11. All of the alumoxanes decompose under mild thermolysis to yield γ-alumina.

Pyryliumverbindungen. 37. Arylbenzene aus 2,4,6‐Triaryl‐pyryliumsalzen und Carbonsäureanhydriden

Pyrylium Compounds. 37. Arylbenzenes from 2,4,6‐Triarylpyrylium Salts and Carboxylic Acid AnhydridesRefluxing 2,4,6‐triarylpyrylium salts 1 with excess carboxylic acid anhydrides (RCH2CO)2O (2a: R = H, 2b: R = Me) in the presence of condensing agents like sodium or potassium acetate, sodium carbonate or methoxide, triethylamine or pyridine results in 1,3,5‐triarylbenzenes 3 (R = H, Me). Under similar conditions, phenylacetic acid anhydride (2c), generated in situ from sodium phenylacetate and excess 2a or 2b, yields 1,2,3,5‐tetraarylbenzenes 3 (R = Ph). Thus, the reaction 1 + 2 → 3 represents a new and simple method for replacing the pyrylium heteroatom =O⊕– by the =CR– moiety (R = H, Me, Ph). The structure of the arylbenzenes 3 was proved by spectroscopic methods, by comparison with literature data or by independent synthesis. As by‐products 2‐acyloxy‐benzophenones 10 are formed. Reaction of 3,5‐dimethyl‐2,4,6‐triphenyl‐pyrylium perchlorate (11) with acetic acid anhydride/sodium acetate (or sodium phenylacetate) takes another course leading to 2‐acetoxy‐3,5‐dimethyl‐4,6‐diphenyl‐benzophenone (15), whereas treatment of 11 with propionic acid anhydride/sodium acetate follows the reaction scheme 1 + 2 → 3 giving 1,3,5‐trimethyl‐2,4,6‐triphenylbenzene (16). The mechanisms of the different pyrylium ring transformations are discussed.