Hydroxy Acetate Research Articles

Effects of acetate and nitrate ions on radical and intercalation reactions initiated by CuZn hydroxy double salts

The role of hydroxy double salts (HDS) in the effective removal of organic contaminants from water is still controversial among researchers. In this work HDS materials, copper-zinc hydroxy acetate (CuZn-HA), and copper-zinc hydroxy nitrate (CuZn-HN) were produced and treated with aqueous methyl orange (MO), acid red 44 (AR44), or congo red (CR) under ambient conditions. Evidence from dye removal testing, materials analyses, and spin trapping measurements suggested possible three removal processes, dye sorption, intercalation reactions, and ·OH radicals assisted oxidation for suitable matching between dye and HDS material. Such three processes are responsible for the complete color (from the aqueous 500 ppm MO and AR44) and TOC removal achieved by using the CuZn-HN. The structural stability of the dye and HDS chemical composition play a key role on the oxidative reactivity and the intercalation ability of the dye in HDS structure.

Effect of Repeated Contact to Food Simulants on the Chemical and Functional Properties of Nano ZnO Composited LDPE Films for Reusable Food Packaging

The effect of repeated contact with food simulants on the properties and functionality of zinc oxide (ZnO) in nanocomposite films was investigated to examine possible safety hazards from the point of view of long-term use as food packaging. Low-density polyethylene (LDPE) embedded with 5 wt% nano-ZnO was immersed in distilled water, 50% ethanol, 4% acetic acid, and n-heptane. The cycle of immersion-rinse-dry was repeated up to 40 times for same sample under constant condition. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), field emission-scanning electron microscopy (FE-SEM), and UV-Vis spectroscopy analyses were performed to identify the changes in the chemical and functional properties of the nanocomposite film. Acetic acid had the greatest impact on the LDPE-ZnO nanocomposite films, while other food simulants caused little change. A new carboxylate bond was formed by the reaction of ZnO with acetic acid, as evidenced by the FTIR spectra. In addition, XRD and XAS confirmed the phase changes of nano-ZnO into zinc salts such as zinc hydroxy acetate or zinc acetate dihydrate. Furthermore, the light barrier property of the nanocomposite film drastically decreased, owing to the change in the bandgap of ZnO and film morphology.

Supramolecular Assembly of Morpholin-4-ium hydroxy(diphenyl)acetate—Structural, Spectral and Nonlinear Optical Analyses

A supramolecular assembly of Morpholin-4-ium hydroxy(diphenyl)acetate (MHA) was synthesized by acquiring morpholine and benzilic acid in equimolar ratio via solvent vaporization technique using methanol as a solvent. The structure of MHA was analyzed by single-crystal X-ray diffraction analysis, which confirms that the crystal is crystallized in a monoclinic crystal system with C2/c centrosymmetric space group. The molecule was stabilized via NH….O and OH..O supramolecular assembly networks. Close contacts are observed over dnorm surface with red spots, from Hirshfeld analysis which are owing to OH…O and NH…O intermolecular interactions. 1H NMR analysis confirmed the migration of proton from benzilic acid to morpholine and in 13C NMR analysis, the signal at δ 176.36 ppm confirmed the presence of highly deshielded carboxylate carbon in the molecule. The vibrational frequencies associated with the functional groups in the MHA crystal are estimated using Fourier transform infrared spectroscopy. Refractive index (n) and extinction coefficient (K), bandgap, optical conductivity (σop), electrical conductivity (σel), optical susceptibility (χop) and polarization (P) were estimated using UV–vis spectroscopy. Fluorescence peaks were observed at 334 and 380 nm via photoluminescence spectroscopy. The third order nonlinear optical properties were obtained using Z-scan studies. The Z-scan curve in the closed aperture configuration indicates the change in refractive index of the MHA crystal with a strong self-defocusing effect.

Solid-Phase Adsorption of Curcumin from Turmeric Extracts by Lamellar Solids and Magnesium Oxide and Hydroxide

Solid-phase extraction and solid-phase adsorption are currently convenient experimental techniques employed to the concentration and purification of secondary metabolites of plant, microbial, and fungal origin. The aim of this research article was the screening of the capacity by 16 solid sorbents including layered structures (hydrotalcites and zirconium phosphates), magnesium oxide and hydroxide, and the phyllosilicates talc and bentonite to selectively concentrate curcumin from raw extract solutions of turmeric, Curcuma longal. (Fam. Zingiberaceae). HPLC analysis, coupled to PDA detection, showed that, among the sorbents employed, magnesium oxide was the most effective one reaching a percentage of adsorption of 96.6%. Other solids able to concentrate curcumin on their surface in percentages varying from48.9 to 68.7% included the hydrotalcites magnesium aluminum hydroxy acetate, magnesium aluminum acetate, magnesium aluminum hydroxy chloride, and magnesium aluminum nitrate, and finally magnesium hydroxide (47.0%). We have finally shown that these sorbents can be readily recovered an recycled without significant losses of adsorption capacities. Although a similar procedure has been recently described using anthraquinones from laxative plants as substrates, the application of these supports for the extraction in the solid phase of curcumin as a representative compound of the diarylheptanoid family is reported herein for the first time in the literature.

Crystal structure of the coordination polymer catena-poly[[bis-[hy-droxy(phen-yl)acetato-κ2 O 1,O 2]zinc(II)]-μ2-1,2-bis-(pyridin-4-yl)ethane-κ2 N:N'

In the title polymeric ZnII compound, [Zn(C8H7O3)2(C12H12N2)] n , the Zn cation is coordinated by two N atoms from 1,2-bis-(pyridin-4-yl)ethane unit and four O atoms from two mandelate [or hy-droxy(phen-yl)acetate] anions in a slightly distorted octa-hedral coordination geometry. The 1,2-bis-(pyridin-4-yl)ethane unit bridges two ZnII cations, related by an inversion centre, to form a polymeric chain along [110]. The crystal structure features extensive O-H⋯O and weak C-H ⋯O hydrogen bonds, with C-H ⋯ π inter-actions and π-π inter-actions also being present. The centroid-centroid distance between the phenyl ring of the mandelate group and the 1,2-bis-(pyridine-4-yl)ethane moiety is 4.951 (2) Å. The 1,2-bis-(pyridin-4-yl)ethane ligand is disordered over two positions, with a refined occupancy of 0.578 (14) for the major component.

Development of a novel comprehensive analytical method for volatile compounds using supercritical fluid chromatography/mass spectrometry with a highly cross-linked styrene divinylbenzene polymer-based column.

Analytical techniques to determine volatile compounds such as flavor, aroma, and fragrances are in high demand due to their wide range of applications in industry, the chemical properties of them are very diverse. Supercritical fluid chromatography (SFC) is capable of high speed, high peak capacity separation and has a high separation coverage. It is also an advantageous for preparative purifications due to its unique mobile phase conditions. However, there is no column commercially available for SFC that is suitable to comprehensively separate volatile compounds. SFC is limited to the use of silica-based columns due to weak retentions and polymer-based column issues such as pressure, swelling and shrinkage tolerances. This study demonstrated comprehensive analytical method for volatile in SFC using a highly cross-linked styrene divinylbenzene (SDVB) polymer-based column, newly developed for SFC. In this study, 23 typical volatile compounds with a wide variety of chemical properties were selected as model compounds. The newly developed SDVB column showed, compared to conventional silica-based columns (k > 0.3), an excellent overall and substantial improved retentions (k > 1.6) under SFC mobile phase conditions. It was also able to retain esters (hydroxy acetate, pentyl butylate, methyl salicylate) and non-polar terpenes (limonene, pinene) that did not show sufficient retention in any other commercially available silica-based columns. Aldehydes reacting on NH2 column due to Schiff base formation were also successfully eluted. It was confirmed that SDVB column provided comprehensive separation and wide coverage for volatile compounds.

Nickel-zinc hydroxy salts with varying amounts of octahedral Zn2+: trends in stability and selectivity in anion exchange reaction

Nickel-zinc hydroxy acetates with varying amounts of octahedral zinc, Ni(3-x)Zn(2+x)(OH)8(OAc)2·mH2O, with x varying from 0 to 2, have been synthesized. The crystallographic ‘a’ parameter increases linearly with octahedral zinc content in the series. While the thermal stability is almost the same for the entire series of compounds, the stability of the compound in the alkaline medium increases with a decrease in octahedral zinc content. The selectivity for chloride ion from a mixture of chloride and bromide ions increases linearly with an increase in octahedral zinc content. The stability of Ni-Zn hydroxy acetate in alkaline medium decreases with increased octahedral substitution of Zn2+, while its selectivity for chloride in anion exchange increases.

The effect of modified Cu(II) kaolinite on interactions with rubberizing components

The interactions of modified Cu(II) kaolinite with rubberizing components, such as stearic acid (SA), zinc oxide (ZnO), sulphur (S) and benzothiazole (Btz) after heating to 150 °C cure temperature were investigated. More over the given prepared modified kaolinite was used for investigation of its effect in model rubber composites. Commercially calcined kaolinite (Kaol) was chemically treated using 0.5 M copper acetate solution in presence of NaOH solution. The modified resulting sample was designated as KCu sample. Different techniques such as Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction patterns analysis (XRD), thermogravimetry/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM) were used to characterize kaolinite and KCu samples. The different techniques (mainly FTIR an XRD) demonstrated that the copper acetate treatment of kaolinite resulted in formation of monohydrate copper hydroxy acetate complex, which influenced the clay surface. XRD pattern and FTIR spectrum of the modified KCu proved that copper acetate treatment did not affect the clay structure significantly. High-temperature X-ray diffraction patterns analysis (HTXRD) was also used for investigate the interactions of modified KCu with rubberizing components. Heating process of KCu and SA without or with ZnO caused the formation of copper stearate and zinc stearate respectively and it let to the occurrence of the stretching vibrations of the carboxyl group (νCOO−). K-Cu2(OH)3Ac·H2O complex on the clay surface influenced the mutual interaction with benzothiazole and it can be seen in IR spectra involving stretching vibrations (νCH) of aromatic ring and the stretching vibrations of functional groups ν(N=CS) and ν(C=N). Finally, for the supplementation of the results, the model rubber composites, filled with kaolinite and KCu and ranged 5, 10 and 20 phr, were prepared. The effect of modified kaolinite on the curing characteristics (minimum torque – ML, maximum torque – MH, optimal vulcanization time – t90, coefficient of vulcanization rate – Rv) and mechanical properties (tensile strength at break – TSb, elongation at break – Eb and hardness) in sulphur-cured natural rubber (NR) composites was investigated. A low viscosity of the NR compounds was achieved throughout the kaolinite and KCu fillers used. The cure time increased by KCu dosing in amount of 10 and 20 phr. The decrease of the maximum torque (MH) value indicates a lower stiffness as well as the viscosity of the mixture at the end of vulcanization. However, the mechanical properties of the vulcanizates with KCu showed significant improvement of TSb and Eb, compared with standard and mixtures with non-modified kaolinite. The modified Cu(II) form of kaolinite had positive effect on the properties of rubber compounds in amount of 5 and 10 phr.

E6130, a Novel CX3C Chemokine Receptor 1 (CX3CR1) Modulator, Attenuates Mucosal Inflammation and Reduces CX3CR1+ Leukocyte Trafficking in Mice with Colitis.

The chemokine fractalkine (CX3C chemokine ligand 1; CX3CL1) and its receptor CX3CR1 are involved in the pathogenesis of several diseases, including inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, rheumatoid arthritis, hepatitis, myositis, multiple sclerosis, renal ischemia, and atherosclerosis. There are no orally available agents that modulate the fractalkine/CX3CR1 axis. [(3S,4R)-1-[2-Chloro-6-(trifluoromethyl)benzyl]-3-{[1-(cyclohex-1-en-1-ylmethyl)piperidin-4-yl]carbamoyl}-4-methylpyrrolidin-3-yl]acetic acid (2S)-hydroxy(phenyl)acetate (E6130) is an orally available highly selective modulator of CX3CR1 that may be effective for treatment of inflammatory bowel disease. We found that E6130 inhibited the fractalkine-induced chemotaxis of human peripheral blood natural killer cells (IC50 4.9 nM), most likely via E6130-induced down-regulation of CX3CR1 on the cell surface. E6130 had agonistic activity via CX3CR1 with respect to guanosine 5'-3-O-(thio)triphosphate binding in CX3CR1-expressing Chinese hamster ovary K1 (CHO-K1) membrane and had no antagonistic activity. Orally administered E6130 ameliorated several inflammatory bowel disease-related parameters in a murine CD4+CD45RBhigh T-cell-transfer colitis model and a murine oxazolone-induced colitis model. In the CD4+CD45RBhigh T-cell transfer model, E6130 inhibited the migration of CX3CR1+ immune cells and decreased the number of these cells in the gut mucosal membrane. These results suggest that E6130 is a promising therapeutic agent for treatment of inflammatory bowel disease.

A new zinc hydroxy acetate hydrogen carbonate lamellar phase for growing large and clean ZnO nanorod arrays.

A novel zinc hydroxy acetate hydrogen carbonate Zn5(OH)8.2(CH3COO)(HCO3)0.8·1.9H2O, isomorphous to Zn5(OH)8(CH3COO)2·xH2O, has been obtained by the reaction of zinc acetate dihydrate in aged ethylenediamine. This phase allows the growth of large arrays of oriented and crystallized nanorods up to 8 μm in length on a substrate, without crystallization of additional particles.

Epoxidation of castor oil with peracetic acid formed in situ in the presence of an ion exchange resin

The influence of reaction variables on the epoxidation of castor oil (CO) in benzene with peracetic acid (P) generated in situ from acetic acid (A) and hydrogen peroxide (H) in the presence of an ion exchange resin as catalyst was examined. The highest relative epoxy yield (REY) of 78.32% was achieved at 323K after 8h when 0.5mol of acetic acid and 1.5mol of 30wt% aqueous hydrogen peroxide per mol of double bond in oil were used in the presence of 15wt% of Amberlite IR-120. The experimental data were fitted by proposed pseudo-homogeneous kinetic model which considers the side reaction of epoxy ring cleavage involving the formation of hydroxy acetate in addition to reactions of the peracetic acid and epoxy compound formation. Temperature dependency of the kinetic parameters is expressed by a reparameterized Arrhenius equation. The constants of the Arrhenius equation were determined by fitting experimental data using the Marquardt method. An increase of all rate coefficients for considered reactions with temperature and good agreement of the calculated reactant and product concentrations with experimental data, indicate the correctness of the proposed kinetic model. The model was compared with pseudo-homogeneous models reported in the literature.

Study of zinc hydroxy acetate as catalyst in the esterification reaction of fatty acids

In this work, the esterification of oleic acid (OA) with methanol (MOH) using layered heterogeneous catalysts under various reaction conditions to produce biodiesel was studied. The zinc hydroxy nitrate salt Zn5(OH)8(NO3)2 · 2H2O (abbreviated Zn-N) and zinc hydroxy acetate Zn5(OH)8(CH3COO)2 · 4H2O (abbreviated Zn-A), which have a layered structure, were synthesized (chemical precipitation) and characterized. Tests for the selection of reaction conditions that maximize the yield to methyl esters were performed. The variables considered were temperature, OA:MOH molar ratio and catalyst loading, selecting the study intervals within the range of feasible operating conditions for the catalysts. The layered solid Zn-A was seen to be more active than Zn-N for the esterification of OA. When working at 140°C, 1:30 OA:MOH molar ratio and catalyst loading of 3% w/w, conversions of 87.0 and 73.4% were obtained for Zn-A and Zn-N, respectively.

Molecular Structural Information of the Atmospheric Corrosion of Zinc Studied by Vibrational Spectroscopy Techniques: I. Experimental Approach

As the nature of the interactions taking place on a metal surface during atmospheric corrosion is inherently complex, it imposes demands on the analytical studies that are needed to understand the fundamentals on a molecular level. Corrosion products may spread on the metal surface forming two- and three-dimensional structures. Thus, it is imperative to use different techniques to resolve the different types of growth. In this first part of a series of two papers, a systematic investigation is made to obtain detailed information on the mechanisms of the onset of atmospheric corrosion of zinc exposed to 115 ppb acetic acid in either dry or humidified air. The vibrational spectroscopy techniques used were vibrational sum frequency spectroscopy (VSFS, interface sensitive), infrared reflection absorption spectroscopy (IRAS, near-surface sensitive), and confocal Raman microspectroscopy (CRM, bulk sensitive). The VSFS selectively targeted the two-dimensional structures, IRAS followed the growth of three-dimensional corrosion products, and CRM could provide a laterally resolved chemical map on localized aggregates of zinc hydroxy acetate and ZnO with bulk character.

ChemInform Abstract: Hydrolytic and Reductive Action of Fermenting Yeast on a Keto Acetate: Synthesis of (+)-endo-Brevicomin.

The keto acetate 1 in fermenting yeast gives the diol 2 with high enantiomeric excess. The product arises from hydrolysis–reduction and is transformed into (+)-endo-brevicomin. The hydroxy acetate from direct reduction of 1 is racemic.

ChemInform Abstract: Aldol Reactions with Erythrulose Derivatives: Stereoselective Synthesis of Differentially Protected syn-α,β-Dihydroxy Esters.

Boron enolates of 1-O-silylated erythrulose 3,4-acetonides prepared with Brown's chloro-dicyclohexylborane/tertiary amine system have been shown to react with achiral aldehydes in a highly stereoselective way to yield a 1,2-syn/1,3-syn stereoisomer. Through oxidative cleavage of the aldol adducts with periodic acid hydrate, enantiopure syn-α,β-dihydroxy esters with either hydroxyl group differently protected have been prepared. These erythrulose derivatives therefore behave as a chiral hydroxy acetate (glycolate) enolate equivalent.

Total Synthesis of Englerin A

Total synthesis of englerin A, a recently reported sesquiterpenoid exhibiting potent and selective growth inhibition against renal cancer cell lines, has been accomplished. The successful strategy featured a [5 + 2] cycloaddition reaction to cast the seven-membered oxabicyclic key intermediate in both racemic and optically active forms. Synthetic (+/-)-englerin A, (+/-)-englerin B, (+/-)-englerin B acetate, a hydroxy acetate, a tert-butyldimethylsilyl ether, and hydrogenated (+/-)-englerin A (31) were tested for their cytotoxicity against a selected panel of cancer cell lines, and the results are path-pointing to more focused structure-activity relationship studies.

Evidence for the formation of anhydrous zinc acetate and acetic anhydride during the thermal degradation of zinc hydroxy acetate, Zn 5(OH) 8(CH 3CO 2) 2·4H 2O to ZnO

Zinc hydroxy acetate, Zn 5(OH) 8(CH 3CO 2) 2·4H 2O, has been prepared by the precipitation method. It has been demonstrated by FTIR analysis that, contrary to previous reports, the interaction of the acetate anion with the matrix cation is ionic. TG analysis, mass spectral analysis of the evolved gases, and in situ variable temperature PXRD and FTIR analysis have shown that decomposition of the material to ZnO involves the formation of Zn 5(OH) 8(CH 3CO 2), Zn 3(OH) 4(CH 3CO 2) 2 and anhydrous zinc acetate (Zn(CH 3CO 2) 2) as some of the acetate-containing intermediate solid products. The acetate anion is finally lost, at temperatures below 400 °C, as acetic anhydride, (CH 3CO) 2O.

Epoxidation of karanja (Pongamia glabra) oil catalysed by acidic ion exchange resin

AbstractKaranja oil with an iodine value of 89 g/100 g was epoxidised in situ with aqueous hydrogen peroxide and acetic acid in the presence of Amberlite IR‐120 acidic ion exchange resin as catalyst. The effect of the operating variables on the oxirane oxygen content, as well as on the oxirane ring stability and the iodine value of the epoxidised karanja oil, were determined. The variables studied were stirring speed, hydrogen peroxide‐to‐ethylenic unsaturation molar ratio, acetic acid‐to‐ethylenic unsaturation molar ratio, temperature, and catalyst loading. The effects of these parameters on the conversion to the epoxidised oil were studied and the optimum conditions for the maximum oxirane content were established. The proposed kinetic model takes into consideration the two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups, and the reaction between the peroxyacid and the epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using Marquardt's algorithm. Good agreement between experimental and predicted data validates the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for the epoxidation reaction was found to be 11 kcal/mol.

Kinetics of epoxidation of jatropha oil with peroxyacetic and peroxyformic acid catalysed by acidic ion exchange resin

The kinetics of epoxidation of jatropha oil by peroxyacetic/peroxyformic acid, formed in situ by the reaction of aqueous hydrogen peroxide and acetic/formic acid, in the presence of an acidic ion exchange resin as catalyst in or without toluene, was studied. The presence of an inert solvent in the reaction mixture appeared to stabilise the epoxidation product and minimise the side reaction such as the opening of the oxirane ring. The effect of several reaction parameters such as stirring speed, hydrogen peroxide-to-ethylenic unsaturation molar ratio, acetic/formic acid-to-ethylenic unsaturation molar ratio, temperature, and catalyst loading on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidised jatropha oil were examined. The multiphase process consists of a consecutive reaction, acidic ion exchange resin catalysed peroxyacid formation followed by epoxidation. The catalytic reaction of peroxyacetic/peroxyformic acid formation was found to be characterised by adsorption of only acetic (or formic) acid and peroxyacetic/peroxyformic acid on the active catalyst sites, and the irreversible surface reaction was the overall rate determining step. The proposed kinetic model takes into consideration two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups and the reaction of the peroxyacid and epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using nonlinear regression method. Good agreement between experimental and predicted data validated the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for epoxidation reaction was found to be 53.6 kJ/mol. This value compares well with those reported by other investigators for the same reaction over similar catalysts.

Divergent Asymmetric Synthesis of 3,5-Disubstituted Piperidines

A divergent synthesis of various 3,5-dioxygenated piperidines with interesting pharmacological properties is described. A mixture of the achiral cis- and racemic trans-3,5-piperidine diol could be efficiently obtained from N-benzylglycinate in five steps by the use of chemoenzymatic methods. In the subsequent enzyme- and Ru-catalyzed reaction, the rac/meso diol mixture was efficiently transformed to the cis-(3R,5S)-diacetate with excellent diastereoselectivity and in high yield. Further transformations of the cis-diacetate selectively delivered the cis-piperidine diol and the cis-(3R,5S)-hydroxy acetate. Alternatively, the DYKAT could be stopped at the monoacetate stage to give the trans-(3R,5R)-hydroxy acetate.