Use Of Carboxylic Acids Research Articles

Pyrylium sulfonate based ionic liquids

Pyrylium salts represent a new group of ionic liquids (ILs) containing a positive charge on the oxygen atom. The novel ILs were obtained starting with 4-pyrones from petroleum feedstock and renewable resources and sulfonic acids. The use of carboxylic acids instead of salts resulted in the formation of cocrystals. The synthesized pyrylium ionic liquids were stable in air and in contact with water and common organic solvents. The permanganate indices which are characteristic for prepared sulfonates were also investigated. The pyrylium ionic liquids were useful as immobilizers and dissolving agents in hydrosilylation reactions.

Anodic aqueous electrophoretic deposition of titanium dioxide using carboxylic acids as dispersing agents

The dispersion of anatase phase TiO 2 powder in aqueous suspensions was investigated by zeta-potential and agglomerate size analysis. The iso-electric point (IEP) of anatase was determined to be at pH 2.8 using monoprotic acids for pH adjustment. In comparison, it was found that the use of carboxylic acids, citric and oxalic, caused a decrease in zeta-potential through the adsorption of negatively charged groups to the particle surfaces. The use of these reagents was shown to enable effective anodic electrophoretic deposition (EPD) of TiO 2 onto graphite substrates at low pH levels with a decreased level of bubble damage in comparison with anodic EPD from basic suspensions. The results obtained demonstrate that the IEP of TiO 2 varies with the type of reagent used for pH adjustment. The low pH level of the IEP and the ability to decrease the zeta-potential through the use of carboxylic acids suggest that the anodic EPD of anatase is more readily facilitated than cathodic EPD.

Corrosion protection of AA2024 sealed anodic layers using the hydrophobic properties of carboxylic acids

The present study investigates the use of carboxylic acids as a post-treatment for sealed AA2024 anodised in tartaric–sulphuric acid electrolyte. Four monocarboxylic acids with different carbon chain lengths were tested ((CH 3–(CH 2) n–COOH with n = 4, 8, 12 and 16). Hydrophobic surface properties after the post-treatment were characterized by contact angle measurements. Electrochemical impedance spectroscopy (EIS) was performed to assess the ability of the four carboxylic acids to form protective films. It was shown that stearic acid ( n = 16) used in its pure molten state was the most efficient. The organic film formed very rapidly (under 5 min) and contributed to the enhancement of the protection in terms of corrosion resistance of the sealed anodic layers. EIS measurements showed the presence of the organic films on the specimen surface.

Alkali‐catalyzed low temperature wet crosslinking of plant proteins using carboxylic acids

We report the development of a new method of alkali-catalyzed low temperature wet crosslinking of plant proteins to improve their breaking tenacity without using high temperatures or phosphorus-containing catalysts used in conventional poly(carboxylic acid) crosslinking of cellulose and proteins. Carboxylic acids are preferred over aldehyde-containing crosslinkers for crosslinking proteins and cellulose because of their low toxicity and cost and ability to improve the desired properties of the materials. However, current knowledge in carboxylic acid crosslinking of proteins and cellulose requires the use of carboxylic acids with at least three carboxylic groups, toxic phosphorous-containing catalysts and curing at high temperatures (150-185 degrees C). The use of high temperatures and low pH in conventional carboxylic acid crosslinking has been reported to cause substantial strength loss and/or undesired changes in the properties of the crosslinked materials. In this research, gliadin, soy protein, and zein fibers have been crosslinked with malic acid, citric acid, and butanetetracarboxylic acid to improve the tenacity of the fibers without using high temperatures and phosphorus-containing catalysts. The new method of wet crosslinking using carboxylic acids containing two or more carboxylic groups will be useful to crosslink proteins for various industrial applications.

Catalytic aza-Wittig Cyclization

The authors report examples of phenanthridine 1 and benzoxazole 2 synthesis by iminophosphorane generation followed by intramolecular aza-Wittig cyclization catalyzed by commercially available phospholene oxide 3. Both azine and azole heterocycles have been synthesized in moderate to good yields (30-87%yield) with attractively low catalyst loadings down to 1 mol%. Furthermore, the use of carboxylic acid derived isocyanates offers a novel disconnection for the synthesis of (benz)oxazoles.

Carboxylic acid-assisted solid-state synthesis of LiFePO4/C composites and their electrochemical properties as cathode materials for lithium-ion batteries

To enhance the capability of LiFePO4 materials, we attempted to coat carbon by incorporating various organic carboxylic acids as carbon sources. The purity of LiFePO4 was confirmed by XRD analysis. Galvanostatic cycling, cyclic voltammetry, electric impedance spectroscopy, and conductivity measurements were used to evaluate the material’s electrochemical performance. The best cell performance was delivered by the sample coated with 60 wt.% malonic acid. Its first-cycle discharge capacity was 149 mA h g−1 at a 0.2 C rate or 155 mA h g−1 at a 0.1 C rate. The presence of carbon in the composite was verified by total organic carbon and Raman spectral analysis. The actual carbon content of LiFePO4 was 1.90 wt.% with the addition of 60 wt.% malonic acid. The LiFePO4/C samples sintered with 60 wt.% various carboxylic acids were measured by Raman spectral analysis. The intense broad bands at 1,350 and 1,580 cm−1 are assigned to the D and G bands of residual carbon in LiFePO4/C composites, respectively. The peak intensity (I D/I G) ratio of the synthesized powders is from 0.907 to 0.935. Carbon coatings of LiFePO4 with low I D/I G ratios can be produced by incorporating carboxylic acid additives before the final calcining process. The use of carboxylic acid as a carbon source increases the overall conductivity (∼10−4 S cm−1) of the material.

Highly Selective Enzymatic Kinetic Resolution of Primary Amines at 80 °C: A Comparative Study of Carboxylic Acids and Their Ethyl Esters as Acyl Donors

Optimization of the kinetic resolution of 2-amino-4-phenyl-butane was achieved at 80 degrees C using CAL-B-catalyzed aminolysis of carboxylic acids and their ethyl esters. The reactions carried out with long chain esters and the corresponding acids as acyl donors proceeded with remarkably high enantioselectivity. The use of carboxylic acids as acylating agents led to a marked acceleration of the reaction rate compared to their ester counterparts. Lauric acid led to enantiomeric excesses superior to 99.5% for both the remaining amine and the corresponding lauramide at 50% conversion (reached in 3 h). These optimized conditions were applied to the resolution of a series of aliphatic and benzylic amines.

Suppression of β‐Hydride Elimination in the Intramolecular Hydrocarboxylation of Alkynes leading to the Formation of Lactones

AbstractPalladium‐catalyzed intramolecular cyclization of the alkynoic acids was studied which gave the five‐ and six‐membered lactones in moderate yields. The reaction can be conducted simply by heating a toluene solution of alkynoic acids at 100 °C in the presence of catalytic amounts of Pd(PPh3)4 and (o‐tol)3P. The key for this transformation is the use of phosphines, instead of carboxylic acids, as an additive. Similar to our previously developed catalytic system the use of carboxylic acid, instead of (o‐tol)3P, resulted into the exclusive formation of the diene.

Synthesis of Copper Sulphide Nanoparticles in Carboxylic Acids as Solvent

A novel method for the preparation of CuS nanoparticles based on the fast nucleation of the sulphide has been developed. The particles have been synthesized by reaction of thioacetic acid with water and copper carboxylates (acetate, propionate) in the corresponding carboxylic acid (acetic, propionic) as a solvent. The use of carboxylic acids presents several advantages: (i) the hydrolysis of the C-S bond is favoured thus producing a fast CuS supersaturation and a high nucleation rate; (ii) the mobility of the precursor molecules is limited so that nucleation events are favoured with respect to particle growth; (iii) the low dielectric constant of the medium stabilises the nanoparticles dispersion by reducing the critical coagulation concentration. The prepared nanoparticles were investigated by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and dynamic light scattering. The nanoparticle suspensions are clear and characterized by a blue-shifted adsorption edge with respect to bulk CuS. Light scattering measurements performed on acetic acid suspensions evidence the formation of monodispersed nanoparticles with an average diameter of about 5 nm.

Formation of α-Tetralone by Intramolecular Friedel-Crafts Acylation

A microscale procedure is described for the formation of the industrially-important compound α-tetralone. This is an example of an intramolecular Friedel–Crafts acylation, utilizing 4-phenylbutanoic acid and a proton source. The title reaction demonstrates the concept of ring-forming reactions and highlights the use of carboxylic acids as an electrophile precursor in electrophilic aromatic substitution reactions.

Cis-Dihydroxylation and Epoxidation of Alkenes by [Mn2O(RCO2)2(tmtacn)2]: Tailoring the Selectivity of a Highly H2O2-Efficient Catalyst

The carboxylic acid promoted cis-dihydroxylation and epoxidation of alkenes catalyzed by [MnIV2O3(tmtacn)2]2+ 1 employing H2O2 as oxidant is described. The use of carboxylic acids at cocatalytic levels not only is effective in suppressing the inherent catalase activity of 1, but also enables the tuning of the catalyst's selectivity. Spectroscopic studies and X-ray analysis confirm that the control arises from the in situ formation of carboxylate-bridged dinuclear complexes, for example, 2 {[MnIII2O(CCl3CO2)2(tmtacn)2]2+} and 3 {[MnII2(OH)(CCl3CO2)2(tmtacn)2]+}, during catalysis. For the first time, the possibility to tune, through the carboxylate ligands employed, both the selectivity and activity of dinuclear Mn-based catalysts is demonstrated. To our knowledge, the system 1/2,6-dichlorobenzoic acid (up to 2000 turnover numbers for cis-cyclooctanediol) is the most active Os-free cis-dihydroxylation catalyst reported to date.

Allylation of Carbon Pronucleophiles with Alkynes in the Presence of Palladium/Acetic Acid Catalyst

AbstractWe have developed an efficient and eco‐chemical process for the allylation of carbon pronucleophiles with alkynes. The reaction of alkynes with various active methynes and methylenes in the presence of Pd(PPh3)4/acetic acid gave the corresponding allylated products in high yields and high regioselectivities. In the present catalytic system, the key is the use of carboxylic acid which dramatically enhances the rate of the reactions. One of the important features of this process is that neither a leaving group is liberated nor is a stoichiometric amount of base needed to generate the nucleophiles.

Infrared methods for monitoring the protonation state of carboxylic amino acids in the photocycle of bacteriorhodopsin.

This review deals with the role of carboxylic amino acids in the proton-transport activity of bacteriorhodopsin. The main focus is on the infrared data, which allow direct monitoring of the protonation/deprotonation of specific residues during the proton movement in the course of the photocycle. Additional attention is paid to the potential use of carboxylic acids in proteins as internal sensors, based on the sensitivity of their IR frequencies to the immediate environment.

Selective monoacylation of ferrocene

A simple, efficient and environment-friendly procedure has been developed for acylation of ferrocene with direct use of carboxylic acid in the presence of trifluoroacetic anhydride on the solid phase of alumina. A wide range of structurally varied carboxylic acids have been found to provide selectively the monoacylated products in high yields.

Determination of inorganic anions on porous graphitic carbon using evaporative light scattering detection: Use of carboxylic acids as electronic competitors

Different volatile carboxylic acids have been investigated as electronic competitors to optimize the separation of 12 common anions (F −, H 2PO 4 −, Cl −, IO 3 −, IO 4 −, Br −, BrO 3 −, SO 4 2−, ClO 3 −, NO 3 −, I −, ClO 4 −) on a porous graphitic carbon (PGC) column with evaporative light scattering detection. The addition of pyridine in the aqueous acidic mobile phase improves the efficiency of the separation and the detector response. The retention of inorganic anions on non-modified PGC is dominated by electronic interactions based purely on donor–acceptor (charge transfer) interaction between the lone pair electrons of the solute and the π-electrons of the PGC.

Liquid-phase oxidation of cyclohexane over CoAPO-5: Synergism effect of coreactant and solvent effect

Cyclohexanone was employed as a coreactant in the liquid-phase oxidation of cyclohexane using glacial acetic acid as a solvent and CoAPO-5 as a catalyst at 105-135°C and 10 kg/cm 2. Addition of cyclohexanone increases the rate of cyclohexane oxidation and selectivity to adipic acid. When the cyclohexanone concentration increases, the rate will increase at 115°C but decrease at 135°C, while the cyclohexanone concentration has no obvious effect on the rate at 125°C. The apparent activation energy for cyclohexane oxidation in the cooxidation system is lower than that of cyclohexane oxidation in the system without the addition of cyclohexanone. An increase of catalyst loading in the cooxidation system, though, increases the rate of cyclohexane oxidation but decreases the yield of adipic acid. Use of carboxylic acid, except formic acid, as the solvent is necessary for the oxidation of cyclohexane. Of acetic acid, propionic acid, butyric acid and n-pentanic acid, the use of propionic acid results in the highest reaction rate when the temperature is below 135°C, while these four carboxylic acids give almost the same conversion after 2 h at 135°C.

The Effects of Carboxylic Acids and their Carboxylates on the Growth of Sargassum horneri and the Use of Carboxylic Acids for Artificial Formation of Seaweed Bed

The Effects of Carboxylic Acids and their Carboxylates on the Growth of Sargassum horneri and the Use of Carboxylic Acids for Artificial Formation of Seaweed Bed

The absorption of phase change substances into commonly used building materials

The absorption of phase change substances into commonly used building materials was studied with the aid of a small series. The phase change materials comprised certain technical grades of carboxylic acids and polyalcohols. The specimens used in the absorption tests were prepared from ordinary Finnish building materials. The use of carboxylic acids makes it possible to achieve considerable increases in capacity. However, in order to prevent drainage or leakage, manufactured products must be coated in one way or another after absorption has occured. Porous wallboard exhibits a particularly strong increase in its storage capacity, and that of gypsum board also increases considerably. Storage capacities achieved with polyalcohols such as neopentylglycol (NPG) were not as high as with carboxylic acids. The largest increase in storage capacity with NPG occured in the porous wallboard. Depending on the building material, more or less of the NPG evaporated with the water.

ChemInform Abstract: Use of Carboxylic Acids as Chiral Solvating Agents for the Determination of Optical Purity of Chiral Amines by NMR Spectroscopy.

ChemInformVolume 20, Issue 18 Preparative Organic Chemistry ChemInform Abstract: Use of Carboxylic Acids as Chiral Solvating Agents for the Determination of Optical Purity of Chiral Amines by NMR Spectroscopy. S. C. BENSON, S. C. BENSON Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorP. CAI, P. CAI Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. COLON, M. COLON Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. A. HAIZA, M. A. HAIZA Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. TOKLES, M. TOKLES Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorJ. K. SNYDER, J. K. SNYDER Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this author S. C. BENSON, S. C. BENSON Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorP. CAI, P. CAI Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. COLON, M. COLON Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. A. HAIZA, M. A. HAIZA Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorM. TOKLES, M. TOKLES Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this authorJ. K. SNYDER, J. K. SNYDER Dep. Chem., Boston Univ., Boston, MA 02215, USASearch for more papers by this author First published: May 2, 1989 https://doi.org/10.1002/chin.198918081AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue18May 2, 1989 RelatedInformation

Use of carboxylic acids as chiral solvating agents for the determination of optical purity of chiral amines by NMR spectroscopy

Use of carboxylic acids as chiral solvating agents for the determination of optical purity of chiral amines by NMR spectroscopy