Carboxylic Acid Salts Research Articles

Investigations on the catalytic carboxylation of olefins with CO2 towards α,β-unsaturated carboxylic acid salts: characterization of intermediates and ligands as well as substrate effects.

The carboxylation of olefins beyond ethylene towards α,β-unsaturated carboxylic acid salts and a detailed investigation on the critical steps in the catalysis are reported. The influence of two chelating phosphine ligands and several olefins on the elemental steps of the catalysis is shown. The work focusses on the formation of intermediate olefin complexes, lactone formation and base induced elimination of the lactone. The direct carboxylation of olefins is possible using nickel catalysts, which opens a new route towards the desired α,β-unsaturated carboxylic acid salts. The reaction works particularly well for 1,3-dienes and proceeds via the formation of allyl-carboxylates. The ability to form such allyl-type lactone complexes seems in this case to be the most challenging step towards satisfactory turnover numbers.

Chemical characterization of agroforestry solid residues aiming its utilization as adsorbents for metals in water

In this work, a study of the correlation between the functional groups present in the chemical structure of the fibers of coconut shells, cocoa and eucalyptus, and their adsorption capacity of Cd+2 and Cu+2 ions from water was performed. The content of soluble solids and reactive phenols in aqueous extracts were determined. The chemical functional groups present in the fibers were examined using the IR spectra. The adsorption capacity of the peels was determined using atomic absorption spectrophotometer. For Cd+2, a significant correlation between the adsorption capacity and some specific chemical functional groups present in the fiber was verified. The potential use of these peels, as adsorbent of Cd+2 ions, is based on the presence of OH functional groups such as aryl-OH, aryl-O-CH2 of phenol carboxylic acids, as well as carbonyl groups derived from carboxylic acid salts, in these fibers.

Simultaneously Converting Carbonate/Bicarbonate and Biomass to Value-added Carboxylic Acid Salts by Aqueous-phase Hydrogen Transfer

A novel approach to coproduce value-added carboxylic acids has been developed via a “one-pot” aqueous-phase hydrogen transfer (APHT) process, in which hydrogen in biomass molecules is transferred to carbonate/bicarbonate ions over supported noble metal nanocatalysts. In mild hydrothermal media, a variety of biomass derived alcohols or polyols have been efficiently converted to carboxylic acids, while simultaneously, formates have been obtained from the reduction of carbonates/bicarbonate salts without using external H2. In an APHT process at the optimized reaction conditions, a high yield of lactate, ∼55%, was achieved using glycerol as the hydrogen donor, and simultaneously, ∼30% of formate was produced by the reduction of sodium bicarbonates over the Pd on a carbon catalyst. The catalyst was stable after three-time consecutive reuse without regeneration, and the possible APHT reaction mechanism was proposed.

Pithecellobium Clypearia Benth Fiber/Recycled Acrylonitrile-Butadiene-Styrene (ABS) Composites Prepared in a Vane Extruder: Analysis of Mechanical Properties and Morphology

The effect of compatibilizer types and concentrations on the mechanical properties and morphology of Pithecellobium Clypearia Benth Fiber (PCBF)/recycled ABS composites prepared by a vane extruder were characterized. In addition, the percentage of compatibilizer was fixed at 8%, and the effect of lubricant concentrations on the mechanical properties and torque behaviors of the composites was also studied. Maleic anhydride grafted ABS (ABS-g-MAH) and maleic anhydride grafted PS (PS-g-MAH) were used as compatibilizers; the lubricant used was Struktol TPW 604 (blend of aliphatic carboxylic acid salts and mono diamides). The composite with 8% ABS-g-MAH showed superior mechanical properties compared to the composite without compatibilizer and the 8% PS-g-MAH compatibilized composites. Compared with PS-g-MAH, ABS-g-MAH was more effective for the composites to improve the interfacial interaction and mechanical properties. The comprehensive mechanical properties of PCBF/recycled ABS composite filled with 4% lubricant were better than the composites without lubricant and the composites with any other content of TPW 604. Moreover, the torque of the composites in an internal mixer decreased with an increasing lubricant content.

Sequential multicomponent synthesis of α-ketoimides, from acyl chlorides, isocyanides, and silver salts of carboxylic acids

A sequential multicomponent synthesis among acyl chlorides, isocyanides, and silver salts of carboxylic acids was developed to synthesize α-ketoimides. The latter undergo an intramolecular aza-Wittig reaction to afford 2-acylquinazolinones.

Nickel-catalyzed direct carboxylation of olefins with CO2 : one-pot synthesis of α,β-unsaturated carboxylic acid salts.

The nickel-catalyzed direct carboxylation of alkenes with the cheap and abundantly available C1 building block carbon dioxide (CO2 ) in the presence of a base has been achieved. The one-pot reaction allows for the direct and selective synthesis of a wide range of α,β-unsaturated carboxylates (TON>100, TOF up to 6 h(-1) , TON=turnover number, TOF=turnover frequency). Thus, it is possible, in one step, to synthesize sodium acrylate from ethylene, CO2 , and a sodium salt. Acrylates are industrially important products, the synthesis of which has hitherto required multiple steps.

Aggregation enhanced emission (AEE) in organic salt: A structure-property correlation based on single crystal studies

Salt formation has been shown as a simple strategy to induce aggregated induced emission or aggregated enhanced emission in primary ammonium salts derived from 9-anthracene carboxylic acid, 1-pyrene carboxylic acid, 3-coumarin carboxylic acid and histamine. All the salts displayed enhanced fluorescence in their solid state compared to that in their solution state. Single crystal structure of the salt of 9-anthracene carboxylic acid i.e., His-anthracene revealed that restricted intramolecular rotation of the fluorphoric moiety (anthracene) was responsible for such radiative pathway leading to enhanced emission. A simple strategy of salt formation has been exploited to induce aggregation-induced emission or aggregation-enhanced emission in primary ammonium salts derived from 9-anthracene carboxylic acid, 1-pyrenecarboxylic acid, coumarin-3-carboxylic acid and histamine.

Influence of the cation type on the DFB lasing performance of dye-doped azobenzene-containing polyelectrolytes

The well-known commercially available azobenzene-containing polyelectrolyte poly{1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt} (PAZO-Na) has been easily modified by converting it into carboxylic acid and different salts. These new materials, similar to original PAZO-Na, were used as matrices to create DFB lasers based on polarization gratings. Such matrix modification allowed us to obtain laser generation with the laser dye 1,2,3,5,6,7-hexamethyl-8-cyanopyrromethene-difluoroborate complex (pyrromethene 650), to increase the laser device stability (up to a half-life time of 4 × 104 pulses) and to considerably increase the laser efficiency (up to 9%). Therefore, these polymer composites can be considered as cheap and promising materials for photonics, optoelectronics, and sensor applications.

Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

Abstract. We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas-phase Master Chemical Mechanism version 3.2 (MCMv3.2), an aerosol dynamics and particle-phase chemistry module (which considers acid-catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion-limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study (1) the evaporation of liquid dioctyl phthalate (DOP) particles, (2) the slow and almost particle-size-independent evaporation of α-pinene ozonolysis secondary organic aerosol (SOA) particles, (3) the mass-transfer-limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), and (4) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. In the smog chamber experiments, these salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar-like amorphous-phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if the concentration of low-volatility and viscous oligomerized SOA material at the particle surface increases upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass-transfer-limited uptake of condensable organic compounds onto wall-deposited particles or directly onto the Teflon chamber walls of smog chambers can have a profound influence on the observed SOA formation. During the early stage of the SOA formation the wall-deposited particles and walls themselves serve as an SOA sink from the air to the walls. However, at the end of smog chamber experiments the semi-volatile SOA material may start to evaporate from the chamber walls. With these four model applications, we demonstrate that several poorly quantified processes (i.e. mass transport limitations within the particle phase, oligomerization, heterogeneous oxidation, organic salt formation, and chamber wall effects) can have a substantial influence on the SOA formation, lifetime, chemical and physical particle properties, and their evolution. In order to constrain the uncertainties related to these processes, future experiments are needed in which as many of the influential variables as possible are varied. ADCHAM can be a valuable model tool in the design and analysis of such experiments.

Synthesis and Properties of Cross-Linkable Waterborne Polyurethane/HMMM-CNT Nanocomposite

A series of cross-linked waterborne polyurethane/hexamethoxymethylmel-amine-carbon nanotube nanocomposites (WBPU/HMMM-CNT) were synthesized using carboxylic group functionalized CNT. The carboxylic groups on CNT were reacted with the methoxy groups of HMMM to get bonded HMMM-CNT. Unreacted methoxy group of HMMM-CNT was crosslinked with the carboxylic acid salt groups of WBPU and made crosslinked WBPU/HMMM-CNT nanocomposite. The mechanical properties (tensile strength and Young’s modulus) of conventional WBPU, crosslinked WBPU/HMMM, WBPU/CNT and WBPU/HMMM-CNT nanocomposites were compared under three conditions: untreated, wet and dried. It was observed that the mechanical properties of the crosslinked WBPU/HMMM-CNT nanocomposites were the least affected by water compared to conventional WBPU, crosslinked WBPU/HMMM, and WBPU/CNT nanocomposites. Differential scanning calorimetry (DSC) analysis also confirmed that the WBPU/HMMM-CNT nanocomposite can absorbed least water which can be easily removed by heating without destroying their crystalline structure. Crosslinked WBPU/HMMM-CNT nanocomposite recovered most of its mechanical properties of (with optimum HMMM-CNT content) after drying.

Reaction of (ethoxycarbonylfuryl)methanephosphonates with diethyl carbonate in presence of sodium foil

Reaction of (ethoxycarbonylfuryl)methanephosphonates with diethyl carbonate in presence of sodium foil is studied. It is shown that if the acidifying group is conjugated with the carbanion center of 2-furylmethanephosphonate, addition of the carbanion to the carbonyl group of diethyl carbonate takes place to give 2-furylacetic acid derivatives in high yield. Sodium salts of these CH-acids are synthesized, isolated, and characterized. Their alkylation with alkyl bromoacetates is carried out. If ethoxycarbonyl group is not conjugated with the carbanion center, conversion of starting phosphonate and yield of adduct sharply decreases. Alkyl (2- and 4-ethoxycarbonylfur-3-yl)methanephosphonates immediately after acylation with diethyl carbonate are reduced with sodium-diethyl carbonate system to form alkyl 1-(2- and 4-ethoxycarbonylfur-3-yl)-ethanephosphonates. Formation of intermediate reduction product, the phosphorylated furylacetic aldehyde is also fixed spectroscopically. Simultaneously with the reduction dealkylation of ester group of starting phosphonates and alkyl 1-(3-furyl)ethanephosphonates takes place leading to the carboxylic acid salts. Alkyl (2-methyl-5-ethoxycarbonylfur-3-yl)methanephosphonate does not take part in condensation. It gives only the products of dealkylation under the action of sodium ethylate forming from diethyl carbonate.

Partial Recovery of Aliphatic Carboxylic Acids and Sodium Hydroxide from Hardwood Black Liquor by Electrodialysis

The partial recovery of sodium as NaOH and sodium-free aliphatic carboxylic acids (formic and acetic acids together with various hydroxy carboxylic acids) from alkaline hardwood black liquor (BL, pH about 14) was studied by using electrodialysis (ED). In the first phase, the lignin was partly (about 59% of the initial lignin) precipitated from BL by carbonation (pH to 8.5). Furthermore, the carbonated liquor, mainly containing NaHCO3/Na2CO3 and Na salts of aliphatic carboxylic acids and lignin, was subjected to ED for recovering NaOH and sodium-free aliphatic acids. In the second phase, the carbonated BL was further acidified with H2SO4 (pH to about 2.5) for precipitating more lignin (about 90% of the initial lignin) with the simultaneous liberation of aliphatic acids. The Na2SO4 that was formed was then separated from the acidified liquor by precipitation with methanol and treated by ED to produce NaOH and H2SO4. For ED experiments, a batch laboratory-scale apparatus containing cation selective and bipolar membranes was used at 20 V. Within an ED treatment time of 5 h the recovery rate of sodium from carbonated BL, model Na2SO4, and precipitated Na2SO4 was 0.044, 0.110, and 0.104 mol Na/h, corresponding to an energy consumption of 1.76, 0.38, and 0.43 kWh/mol Na, respectively. In each case, the total amount of sodium recovered was about 90%.

Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide.It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25nm ZnO thin film deposited with ozone at 100°C were quite close to those obtained earlier with ALD Al2O3 of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al2O3 thin films and bacteria promoted antibacterial activity.

Hydrogen-bonded two- and three-dimensional polymeric structures in the ammonium salts of 3,5-dinitrobenzoic acid, 4-nitrobenzoic acid and 2,4-dichlorobenzoic acid

The structures of ammonium 3,5-dinitrobenzoate, NH4(+) · C7H3N2O6(-), (I), ammonium 4-nitrobenzoate dihydrate, NH4(+) · C7H4NO4(-) · 2H2O, (II), and ammonium 2,4-dichlorobenzoate hemihydrate, NH4(+) · C7H3Cl2O2(-) · 0.5H2O, (III), have been determined and their hydrogen-bonded structures are described. All three salts form hydrogen-bonded polymeric structures, viz. three-dimensional in (I) and two-dimensional in (II) and (III). With (I), a primary cation-anion cyclic association is formed [graph set R4(3)(10)] through N-H...O hydrogen bonds, involving a carboxylate group with both O atoms contributing to the hydrogen bonds (denoted O,O'-carboxylate) on one side and a carboxylate group with one O atom involved in two hydrogen bonds (denoted O-carboxylate) on the other. Structure extension involves N-H...O hydrogen bonds to both carboxylate and nitro O-atom acceptors. With structure (II), the primary inter-species interactions and structure extension into layers lying parallel to (001) are through conjoined cyclic hydrogen-bonding motifs, viz. R4(3)(10) (one cation, an O,O'-carboxylate group and two water molecules) and centrosymmetric R4(2)(8) (two cations and two water molecules). The structure of (III) also has conjoined R4(3)(10) and centrosymmetric R4(2)(8) motifs in the layered structure but these differ in that the first motif involves one cation, an O,O'-carboxylate group, an O-carboxylate group and one water molecule, and the second motif involves two cations and two O-carboxylate groups. The layers lie parallel to (100). The structures of salt hydrates (II) and (III), displaying two-dimensional layered arrays through conjoined hydrogen-bonded nets, provide further illustration of a previously indicated trend among ammonium salts of carboxylic acids, but the anhydrous three-dimensional structure of (I) is inconsistent with that trend.

Unexpected reaction of 2-bromomethyl-1,3-thiaselenole with salts of carboxylic acids

Unexpected reaction of 2-bromomethyl-1,3-thiaselenole with salts of carboxylic acids

Hydrocarbon-soluble metal corrosion inhibitors. II. Physicochemical aspects of inhibitor action. Amides and salts of carboxylic acids

Some molecular aspects of protective action and specific behavior of hydrocarbon-soluble amides and salts of certain amines and morpholine with carboxylic acids in aqueousorganic environments are considered. The electron densities on those heteroatoms which are presumably responsible for adsorption and inhibition, as well as the Hansch -constants have been calculated. Hypothetical adsorption models have been suggested for tridecanoic acid amides with hexylamine, cyclohexylamine, piperidine, piperazine, morpholine and the cyclohexylamine quaternary salt. Hypothetical adsorption schemes and the probable inhibitor efficiency of the products have been analyzed with consideration for data on the electronic charges and hydrophobicity of the molecules.

New crystalline salt forms of levofloxacin: conformational analysis and attempts towards the crystal structure prediction of the anhydrous form

Structural information on the anhydrous forms of levofloxacin, a broad spectrum fluoroquinolone antibiotic drug, is limited as it readily converts into the more stable hemihydrate form. Obtaining single crystals of the anhydrous form will be a challenge in this situation. Herein, we report six novel carboxylic acid salt forms of levofloxacin and our attempts towards the crystal structure prediction of its anhydrous form. In-depth analysis of various possible conformations of levofloxacin was performed with the help of high level density functional theory calculations. Useful structural insights obtained from crystal structure analysis of two known hydrates and six new salt forms of levofloxacin were utilized to identify the most probable supramolecular synthons. Synthon information obtained from these crystalline forms was used in the re-ranking of computationally generated crystal structures to arrive at a set of most probable crystal structures for the anhydrous form. A comparison of the crystal structures of the two hydrate forms with the predicted anhydrous form of levofloxacin was performed to understand the hydration–dehydration behaviour.

Optimized preparation for large surface area activated carbon from date (Phoenix dactylifera L.) stone biomass

The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L−1) and activation temperature, 900 °C. The Brunauer–Emmett–Teller (BET) surface area of optimized activated carbon was found to be 1225 m2 g−1, and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 °C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt ʋ(CO) 1561.22 cm−1 and 1384.52 cm−1, aliphatic hydrocarbons ʋ(C–H) 2922.99 cm−1 (C–H sym./asym. stretch frequency), aliphatic phosphates ʋ(P–O–C) 1054.09 cm−1, and secondary aliphatic alcohols ʋ(O–H) 3419.81 cm−1 and 1159.83 cm−1.

High-temperature alkaline stability of cement set retarders and their performance at 70–90°C

Hydroxycarboxylic acid salt (sodium gluconate), sodium lignosulfonate and a combination of carboxylic acid and sulfonate-type retarder (poly(4-styrenesulfonic acid-co-maleic acid) sodium salt) are typical set retarders for oil-well cement. The potential high-temperature alkali degradation of these retarders is assessed, and its role in altering the kinetics of cement hydration at temperatures between 70 and 90°C. The high-temperature alkaline stability of cement set retarders is poorly studied. However, it may represent one way to understand the delay in hydration induced by such additives, and the discontinuity of cement hydration, with the longer setting times at higher temperatures in that range. Degradation products are identified and their thermal stability is evaluated. Retarders containing carboxylic acid become partially fragmented at high pH and 90°C. The effect on cement setting kinetics is similar for hydrolysed retarders containing carboxylic acid groups: the setting times are longer at 80°C than at 70 and 90°C. The sulfonate groups of lignosulfonate-type retarder, treated at pH 13·4, 90°C, are partially converted to sulfate and the ether groups to alkoxides. The setting time changes linearly with temperature for the high-pH-treated lignosulfonate retarder in the studied temperature range.

Conformation of the umifenovir cation in the molecular and crystal structures of four carboxylic acid salts

The umifenovir salts of maleic, salicylic, glutaric, and gentisic acid as well as the chloroform solvate of the salicylate were prepared. Single crystals of the five compounds were obtained and their molecular and crystal structures determined by X-ray diffraction. In each structure the conformation of phenyl ring with respect to the indole group of the umifenovir moiety is different. The water solubility and melting points of the studied umifenovir salts have been determined.