Mixture Of Carboxylic Acids Research Articles

Liquid–liquid equilibria measurements of ternary systems (acetonitrile + a carboxylic acid + dodecane) at 303.15 K

Liquid–liquid equilibrium (LLE) data are reported for the ternary mixtures of (acetonitrile+a carboxylic acid+dodecane) at 303.15K under atmospheric pressure, where a carboxylic acid refers to acetic acid, propanoic acid, butanoic acid, 2-methylpropanoic acid, pentanoic acid and 3-methylbutanoic acid. The area of the two-phase heterogeneous region for the carboxylic acid mixtures decreases in the order: acetic acid>propanoic acid>butanoic acid>2-methylbutanoic acid>pentanoic acid>3-methylbutanoic acid. The relative mutual solubility of each of the carboxylic acids is higher in acetonitrile layer than in dodecane layer. Three 3-parameter equations have been fitted to the binodal curve data. The NRTL and UNIQUAC models were used to correlate the experimental data. The NRTL model fitted the experimental data far better than the UNIQUAC model with the average mean square deviation of 0.0030 mole fraction as compared to 0.2870 mole fraction for UNIQUAC. Selectivity values for solvent separation efficiency were calculated from the tie-line data and show that separation of carboxylic acids from dodecane is feasible by extraction with acetonitrile.

Conversion of glucose into 5-hydroxymethylfurfural with boric acid in molten mixtures of choline salts and carboxylic acids

The conversion of glucose into a potential platform chemical for fuels and plastics, 5-hydroxymethylfurfural (HMF), has been studied using B(OH)3 as a promoter in different solvents, namely molten mixtures made of choline salts and carboxylic acids, with the aim of developing an inexpensive and less harmful alternative to Cr/ionic liquid systems. Choline chloride-based molten mixtures afforded poor yields of HMF, whereas the yields were improved by replacing choline chloride with choline dihydrogen citrate. The combination of choline dihydrogen citrate and glycolic acid was the best choice, providing an HMF yield of ∼60% at 140 °C within 4 h by adding a small volume of water as a co-solvent.

Consideration of dimerization for property prediction with COSMO-RS-DARE

With COSMO-RS, interactions between molecules are described with statistical thermodynamics of interacting surface segments. Thereby, all spatial information is neglected. Hence, concerted multiple contacts of molecules, and therefore dimerization, are not captured with COSMO-RS.In this study COSMO-RS-DARE, an extension of COSMO-RS for consideration of dimerization when predicting liquid phase properties, is evaluated for binary mixtures of dimerizing carboxylic acids and nonpolar components. For this extension two new parameters are introduced. These dimerization parameters are determined for the above-mentioned mixtures. Furthermore, a generalization of these parameters for a general application to that type of systems observed in this study is investigated.For this purpose activity coefficients for the binary mixtures of carboxylic acids and nonpolar components, calculated with COSMO-RS-DARE, are fitted to activity coefficients determined using experimental data by varying the new parameters.A better description of mixtures containing a dimerizing carboxylic acid and a nonpolar component can be achieved with COSMO-RS-DARE. If the dimerization parameters are determined for a single system, this system can be described with a high accuracy. Good results are achieved also with dimerization parameters generalized for a general application. This holds for systems used to determine these parameters as well as for systems not used to determine these parameters.Therefore, it can be stated that activity coefficients calculated with COSMO-RS-DARE have a higher accuracy than activity coefficients calculated with COSMO-RS without this extension. Nevertheless, further investigations with more systems are necessary to evaluate portability of COSMO-RS-DARE to a broader range.

Influence of water matrix on copper-catalysed continuous ozonation and related ecotoxicity

The continuous ozonation of a mixture of carboxylic acids (formic, acetic, oxalic and maleic) has been performed under non-catalytic and copper-catalysed ozonation using a synthetic water matrix and a real sewage treatment plant (STP) effluent. The aim was to study the effect of water matrix on catalytic performance, particularly considering the toxicity of treated water to aquatic organisms. The non-catalytic ozonation of carboxylic acids in synthetic water resulted in a low reduction (36%) of the total organic carbon (TOC), the main feature being the accumulation oxalic acid due to the partial oxidation of maleic acid. Catalytic ozonation, adding copper concentration of 20μgL−1, achieved a TOC reduction of 75%, mainly due to the total depletion of oxalic acid. In wastewater effluent, the same general pattern was found with oxalic acid as the main by-product and its almost complete removal in catalytic ozonation. However, to attain the latter it was necessary to use copper concentrations as high as 100μgL−1. Copper proved to be a good catalyst for the oxidation of oxalic at near neutral pH, with short reaction times and matrix with high scavenging rate. The aquatic toxicity of treated mixtures was studied by means of five standard species placed on different trophic levels: Vibrio fischeri, Pseudomonas putida, Pseudokirchneriella subcapitata, Tetrahymena thermophila and Daphnia magna. The results showed that copper in STP effluent was less toxic than in synthetic water, an effect attributed to copper complexation with organic and inorganic compounds present in the matrix. The reduced biological availability could also explain the lower catalytic effect observed in real wastewater.

Mixed Micelles of Tetrameric Acids and Naphthenic Acids in Water

This article presents a characterization of the structures formed in aqueous solution by a mixture of carboxylic acid and a tetrameric acid molecule: either C80-tetraacid (also known as ARN), which is an aliphatic molecule present in crude oil and responsible for the formation of deposits, or BP-10, a molecule designed to mimic the properties of the C80-tetraacid. These molecules have four carboxylic functions at the end of four interconnected hydrocarbon chains and can be dissolved in aqueous solution in basic media. The structures have been analyzed by dynamic light scattering (DLS) and small-angle neutron scattering (SANS) techniques. It has previously been shown from SANS measurements that BP-10 in sodium form (Na4BP-10) self-associate in solution to form nanosized micelles. We show here that sodium carboxylates, when present, can be incorporated into the BP-10 micelles. This incorporation is a function of the CMC of the sodium carboxylates. In contrast, the other tetrameric acid—C80-TA in sodium form...

Unravelling the surface chemistry of metal oxide nanocrystals, the role of acids and bases.

We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting nanocrystals could be transferred to nonpolar media using a mixture of carboxylic acids and amines. Using solution (1)H NMR, FTIR, and elemental analysis, we studied the details of the transfer reaction and the surface chemistry of the resulting sterically stabilized nanocrystals. As-synthesized nanocrystals are charge-stabilized by protons, with chloride acting as the counterion. Treatment with only carboxylic acids does not lead to any binding of ligands to the HfO2 surface. On the other hand, we find that the addition of amines provides the basic environment in which carboxylic acids can dissociate and replace chloride. This results in stable, aggregate-free dispersions of HfO2 nanocrystals, sterically stabilized by carboxylate ligands. Moreover, titrations with deuterated carboxylic acid show that the charge on the carboxylate ligands is balanced by coadsorbed protons. Hence, opposite from the X-type/nonstoichiometric nanocrystals picture prevailing in literature, one should look at HfO2/carboxylate nanocrystals as systems where carboxylic acids are dissociatively adsorbed to bind to the nanocrystals. Similar results were obtained with ZrO2 NCs. Since proton accommodation on the surface is most likely due to the high Brønsted basicity of oxygen, our model could be a more general picture for the surface chemistry of metal oxide nanocrystals with important consequences on the chemistry of ligand exchange reactions.

Degradation of 2,4-D herbicide in a recirculation flow plant with a Pt/air-diffusion and a BDD/BDD cell by electrochemical oxidation and electro-Fenton process

Here, 2.5L of solutions of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide of pH 3.0 have been degraded by electrochemical oxidation (EO) and electro-Fenton (EF) using a recirculation flow plant equipped with a single Pt/air-diffusion or BDD/BDD cell containing electrodes of 20cm2 area. In EO, organics were mainly oxidized by OH formed at the anode surface from water oxidation, whereas in EF they were also destroyed in the bulk by OH generated from Fenton’s reaction between added Fe2+ and H2O2 produced at the cathode. In both treatments, the use of a single BDD/BDD cell always allowed larger decontamination due to the higher ability of OH at the BDD surface to mineralize organic intermediates. The most potent EF process with this cell gave 59% mineralization with 23% efficiency and 0.42kWhg−1 TOC specific energy after 300min at 0.5A. The coupling of Pt/air-diffusion and BDD/BDD cells with equal individual current in EF led to similar mineralization degree to that found for the Pt/air-diffusion one at the same total current, but in much shorter time. The effect of current on the mineralization rate, mineralization current efficiency and specific energy of each method was examined. The influence of herbicide concentration on the EF performance of the coupled cell at 2.0A/2.0A was also studied and 83% mineralization was obtained as maximal for 276mgL−1 2,4-D. The herbicide decay always obeyed a pseudo-first-order reaction. A mixture of short-linear carboxylic acids was detected in all final electrolyzed solutions, which were the major organic by-products generated using the single BDD/BDD cell but formed in minor proportion in the EF processes with the Pt/air-diffusion and coupled ones.

Effect of temperature on density, sound velocity, refractive index and their derived properties for the binary systems (heptanoic acid + propanoic or butanoic acids)

In this work, the effect of temperature on density (ρ), sound velocity (u), refractive index (n) and their derived properties for carboxylic acid mixtures was studied. The thermophysical properties: density, sound velocity and refractive index were measured over the entire composition range at T=(293.15, 298.15, 303.15, 308.15 and 313.15)K and at p=0.1MPa for the binary systems (heptanoic acid+propanoic or butanoic acids). The mass fraction of water was found to be unusually large and could not be reduced further. The Lorentz–Lorenz approximation was used to predict the density from refractive index or the refractive index from density of the binary mixtures. Sound velocity mixing rules were applied to the experimental sound velocity data. Excess molar volumes, VmE, isentropic compressibilities, κs, excess isentropic compressibilities, κsE, and deviation in refractive indices, Δn, were also calculated from the experimental data. The Redlich–Kister polynomial equation was fitted to the excess properties and the deviation in refractive index data. Thermophysical properties are useful in understanding the intermolecular interactions between the components of mixtures.

Novel precursors for production of 3-hydroxyvalerate-containing poly[(R)-hydroxyalkanoate

Polyhydroxyalkanoates (PHAs) with tailored properties are needed to meet consumer demands regarding the use of eco-compatible biobased polymeric materials and relevant plastic items. Inserting 3-hydroxvalerate (3HV) monomeric units in PHA biopolyesters results in poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (PHBHV) copolyesters aimed at their conversion into production of biodegradable eco-friendly plastic items. As inexpensive novel precursor substrate structurally related to 3HV, a mixture of odd-numbered carboxylic acids with 9–17 carbon atoms was produced by oxidative ozonolysis of alkenes. This mixture was successfully applied for biomediated PHBHV production by Cupriavidus necator. Applying this mixture as carbon substrate, a molar 3HV fraction exceeding 0.12 was obtained. The isolated copolyesters featured a low degree of crystallinity, narrow molar mass distribution, and low melting temperatures. These properties should make application of the novel 3HV-precursors interesting for large-scale production of easily processable copolyesters.

A Single-Pot Synthesis of Atovaquone: An Antiparasitic Drug of Choice

The present article relates to a practical, economically viable, and validated at industrial scale, single-pot synthetic route for preparation of atovaquone, one of the most versatile antiparasitic drugs of choice used for the prophylaxis and treatment of diseases such as pneumocystis, toxoplasmosis, babesiosis, coccidiosis, and malaria. However, owing to the extremely poor yields of synthesis and very high doses of treatment (due to poor bioavailability) the cost of treatment with this drug is not affordable by the patients in need, particularly in the third world countries where these diseases are most prevalent. Unlike most of the reported processes which use 2-chloronaphthoquinone and pure trans-4-chlorophenyl cyclohexane carboxylic acid, our process is based on the decarboxylative alkylation of isomeric mixture of 4-chlorophenyl cyclohexane carboxylic acid with 1,4-naphthoquinone to give 42% overall yield of atovaquone, 10 times higher than from the reported process (4%) from the innovators of this drug.

Biodegradation of naphthenic acids in oils sands process waters in an immobilized soil/sediment bioreactor

Aqueous extraction of bitumen in the Alberta oil sands industry produces large volumes of oil sands process water (OSPW) containing naphthenic acids (NAs), a complex mixture of carboxylic acids that are acutely toxic to aquatic organisms. Although aerobic biodegradation reduces NA concentrations and OSPW toxicity, treatment times are long, however, immobilized cell reactors have the potential to improve NA removal rates. In this study, two immobilized soil/sediment bioreactors (ISBRs) operating in series were evaluated for treatment of NAs in OSPW. A biofilm was established from microorganisms associated with sediment particles from an OSPW contaminated wetland on a non-woven textile. At 16months of continuous operation with OSPW as the sole source of carbon and energy, 38±7% NA removal was consistently achieved at a residence time of 160h at a removal rate of 2.32mgNAsL−1d−1. The change in NA profile measured by gas chromatography–mass spectrometry indicated that biodegradability decreased with increasing cyclicity. These results indicate that such treatment can significantly reduce NA removal rates compared to most studies, and the treatment of native process water in a bioreactor has been demonstrated. Amplification of bacterial 16S rRNA genes and sequencing using Ion Torrent sequencing characterized the reactors’ biofilm populations and found as many as 235 and 198 distinct genera in the first and second bioreactor, respectively, with significant populations of ammonium- and nitrite-oxidizers.

Effect of an active packaging with citrus extract on lipid oxidation and sensory quality of cooked turkey meat

An antioxidant active packaging was prepared by coating a citrus extract, consisting of a mixture of carboxylic acids and flavanones, on polyethylene terephthalate trays. The effect of the packaging in reducing lipid oxidation in cooked turkey meat and on meat pH, colour characteristics and sensorial parameters was investigated. An untrained sensory panel evaluated the odour, taste, tenderness, juiciness and overall acceptability of the meat, using triangle, paired preference and quantitative response scale tests. A comparison between the antioxidant effects of the different components of the extract was also carried out. The packaging led to a significant reduction in lipid oxidation. After 2days of refrigerated storage the sensory panel detected differences in odour and, after 4days, rated the meat stored in the active packaging higher for tenderness and overall acceptability. Citric acid appeared to be the most important component of the extract with regard to its antioxidant potency.

ChemInform Abstract: Ruthenium‐Catalyzed Oxidation of Alcohols by Bromate in Water.

AbstractAn efficient catalyst is applied to the oxidation of secondary‐ and primary alcohols to the corresponding ketones (II) or mixtures of aldehydes (IV) and carboxylic acids (V) with excellent conversions at room temperature.

Indigenous microbes survive in situ ozonation improving biodegradation of dissolved organic matter in aged oil sands process-affected waters

The oil sands industry faces significant challenges in developing effective remediation technologies for process-affected water stored in tailings ponds. Naphthenic acids, a complex mixture of cycloaliphatic carboxylic acids, have been of particular concern because they concentrate in tailings ponds and are a component of the acutely toxic fraction of process water. Ozone treatment has been demonstrated as an effective means of rapidly degrading naphthenic acids, reducing process water toxicity, and increasing its biodegradability following seeding with the endogenous process water bacteria. This study is the first to examine subsequent in situ biodegradation following ozone pretreatment. Two aged oil sands process-affected waters from experimental reclamation tailings ponds were ozonated to reduce the dissolved organic carbon, to which naphthenic acids contributed minimally (<1mgL−1). Treatment with an ozone dose of 50mgL−1 improved the 84d biodegradability of remaining dissolved organic carbon during subsequent aerobic incubation (11–13mgL−1 removed from aged process-affected waters versus 5mgL−1 when not pretreated with ozone). The ozone-treated indigenous microbial communities were as capable of degrading organic matter as the same community not exposed to ozone. This supports ozonation coupled with biodegradation as an effective and feasible treatment option.

Thermophysical Properties of Binary Liquid Systems of Ethanoic Acid, Propanoic Acid, and Butanoic Acid with Benzene or Acetophenone

The density (), viscosity (), and surface tension () of binary mixtures of carboxylic acids (CAs) (ethanoic acid (EA), propanoic acid (PA), butanoic acid (BA)) + benzene (BEN) or acetophenone (ACT) have been measured at 298.15, 308.15, and 318.15 K. From the experimental results, excess values of molar volume (), viscosity (), Gibb's free energy for the activation of low (), and surface tension () were evaluated and fitted to a Redlich-Kister type of equation. The parameter “” of Grunberg and Nissan expression has also been calculated. From the sign and magnitude of , , , , and “” values, it is concluded that specific interactions are present in CA+ACT system and these interactions are absent in CA + BEN mixtures. Various viscosity and surface tension models have been used to test the consistency of the data.

Interaction between the Cesium Cation and Cesium Carboxylates: An Extended Cs+ Basicity Scale.

The interaction between the cesium cation and fulvic or humic acids is supposed to play a role in cesium mobility in the environment, which is of importance in the context of geographical dispersion or concentration of the corresponding radionuclides. Among the singly charged positive clusters generated by electrospray ionization of mixtures of carboxylic acids (AH) and cesium salts (nitrate, iodide, or trifluoroacetate), the cluster [A- Cs+ ]Cs+ [A'- Cs+ ] was subjected to collision-induced dissociation. The fragmentation into Cs+ [A- Cs+ ] and Cs+ [A'- Cs+ ] was treated using the kinetic method. A gas-phase basicity ladder was built by a step-by-step addition of the relative basicity data. The relative basicity scale deduced from the kinetic method was calibrated using the affinity and basicity (the enthalpy and Gibbs energy scales, respectively) obtained from DFT calculations. The enhanced basicity of the polyacid salts, relative to their monoacid salts, as well as the substituent effects on aliphatic and aromatic structures, are discussed.

Thiol containing carboxylic acids remove the CTAB surfactant onto the surface of gold nanorods: An FTIR spectroscopic study

Gold nanorods are mostly synthesized by chemical methods, using a directing agent: CTAB (cetyl-trimethyl-ammonium bromide). Due to the various applications of gold nanorods, the necessity to modify the surface functionalization appears. Thiol containing molecules are used as direct or cross-linking agents in the functionalization of gold nanorods. In this study we show that a thiol containing carboxylic acid mixture is able to remove a large part of CTAB molecules that surround the gold nanorods, and not only to cover the CTAB protecting layer. Using a simple FTIR spectroscopic method, it is possible to quantitatively determine the percentage of CTAB that is replaced by the functionalizing agent.

Selective biodegradation of naphthenic acids and a probable link between mixture profiles and aquatic toxicity

The toxicity of oil sands process-affected waters (OSPW) from the Athabasca Oil Sands (AOS) in northern Alberta, Canada, is related to a relatively persistent group of dissolved organic acids known as naphthenic acids (NAs). Naphthenic acids are a complex mixture of carboxylic acids, with a general formula C(n)H(2n+Z)O2, where n indicates the carbon number and Z specifies the number of rings in the molecule. The present study is the first to evaluate the potential for the selective biodegradation of NAs and the associated reduction in aquatic toxicity of 2 OSPWs, maintained under 2 different hydraulic retention times and increased nutrient availability (nitrate and phosphate), using flow-through laboratory wetland microcosms over a 52-wk test period. High-performance liquid chromatography/quadrupole time of flight-mass spectrometry analysis was used to track the changes in NA mixture profiles, or "fingerprints," in each treatment over time. Based on first-order degradation kinetics, more rapid degradation was observed for NAs that had lower carbon numbers and fewer degrees of cyclization (NA congeners with carbon numbers 11-16 and Z series -2 to -4; half-lives between 19 and 28 wk). Within the NA mixture fingerprints, the 2 most persistent groups of homologues were also identified (NAs with carbon numbers 17-20 and Z series -6 to -12; half-lives between 37 and 52 wk). The persistence of this group of NAs may aid in explaining the residual chronic toxicological response as measured by the Microtox bioassay (effective concentration for 20%), after the degradation of the more labile fractions of NA mixtures in OSPW.

Influence of Cyclic Dimer Formation on the Phase Behavior of Carboxylic Acids. II. Cross-Associating Systems

The doubly bonded dimer association scheme (DBD) proposed by Sear and Jackson is extended to mixtures exhibiting both self- and cross-associations. The PC-SAFT equation of state is combined with the new DBD association contribution to describe the vapor-liquid equilibria of binary mixtures of carboxylic acids + associating compounds (water, alcohols, and carboxylic acids). The effect of doubly bonded dimers on the phase behavior in such systems is less important than in mixtures of carboxylic acids with nonassociating compounds, due to the cross-associations that compete with the formation of DBDs. Nevertheless, a clear improvement in the description of vapor-liquid coexistence curves is achieved over the classical 2B association model, particularly for the dew point curves.

Esterification Catalysis by Pyridinium p-Toluenesulfonate Revisited—Modification with a Lipid Chain for Improved Activities and Selectivities

The lipid analogs of pyridinium p-toluenesulfonate (PPTS) were examined for catalysis of the condensation of an equimolar mixture of carboxylic acids and alcohols under mild conditions without removal of water. Although PPTS is a poor catalyst, the introduction of a lipid chain and nitro group significantly improved the activity of PPTS and led to selectivity at suppressing the elimination side reactions of alcohols. 2-Oleamido-5-nitro-pyridinium p-toluenesulfonate (6) is a lead catalyst that promoted various esterification reactions with yields up to 99%. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]