Alkaline Aqueous Ethanol Research Articles

Screening and characterization of an acid polysaccharide with antioxidant activity in vitro and in vivo from Dendrobium aurantiacum var. denneanum (Kerr)

Aim: We aimed to monitor an acid polysaccharide with antioxidant activity. Materials and Methods: Three acidic polysaccharides (DAP-A40, DAP-A60, and DAP-A80) were extracted from D. aurantiacum imbricate by alkaline aqueous solution extraction and ethanol precipitation. The structure characterization and antioxidant activity in vitro and in vivo were examined. Results: The molecular weight (MW) of three polysaccharides was 1.70 mol5 Da, 5.78 mol4 Da, and 1.36 mol4 Da, respectively, by high-performance gel chromatography. The consequences of infrared spectrum displayed that three polysaccharides enclosed uronic acid and sulfuric acid groups. DAP-A40 and DAP-A60 were collected of α-configuration pyranose. DAP-A80 was composed of β-configuration pyranose. Antioxidant test exhibited that DAP-A80 had outstanding antioxidant activity. The half-maximal inhibitory concentration of DAP-A80 in dipping power and scavenging the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), DPPH, and OH radicals was 163.5 μg/mL, 613.2 μg/mL, 583.2 μg/mL, and 365.1 μg/mL, respectively. The grades of correlation analysis showed that the ability of DAP-A80 to scavenge ABTS, DPPH, and OH radicals was negatively connected with the MW of polysaccharides and certainly correlated with the content of sulfate group. The results of in vivo experiments exposed that DAP-A80 might knowingly decline the formation of malondialdehyde. High levels of DAP-A80 could evocatively upsurge the activity of superoxide dismutase and GSH-Px in mouse serum. Conclusion: DAP-A80 has an antioxidant effect and can be reconnoitered as a health medicine and food.

Selection of electrode materials for membrane less fuel cells based on immiscible liquids

The possibility of using various materials as electrodes for membraneless fuel cells based on immiscible liquids, both from the standpoint of the thermodynamic possibility of the process and from the point of view of their corrosion resistance, is considered. The corrosion resistance of materials from alloys based on iron, as well as carbon was investigated for use as electrodes in membraneless fuel cells based on immiscible liquids. The possibility of using them instead of electrodes based on ruthenium and platinum in the studied alkaline aqueous ethanol system was shown. It was found that the highest electromotive force in the system occurs when using an activated carbon anode in the top ethanol phase and a carbon steel 10 cathodes in the bottom aqueous phase. The possibility of using activated carbon instead of a ruthenium-coated titanium electrode and platinum-coated titanium electrode, at almost equal exchange currents, will significantly reduce the cost of manufacturing a fuel cell. Thus under certain conditions, this type of fuel cell can compete with membrane fuel cells that have received industrial implementation

Recovery of γ-Oryzanol from Rice Bran Acid Oil by an Acid-base Extraction Method with the Assistance of Response Surface Methodology.

A rapid and low energy consumption method for the recovery of γ-oryzanol from rice bran acid oil (RBAO), a byproduct of rice bran oil (RBO) refining, is presented. The RBAO was converted to the fatty acid ethyl ester (FAEE) and was used as the starting material. The dissolved γ-oryzanol was separated from the FAEE using an acid-base extraction method with alkaline aqueous ethanol and hexane as extraction media. A systematic investigation of the extraction yield was carried out by applying response surface methodology (RSM) based on central composite design (CCD) and Derringer's desirability function. The concentration of NaOH, the percentage of ethanol in water, the hexane content and their interactions showed significant effects on the yield of γ-oryzanol and FAEE. The optimal extraction conditions were as follows: extraction time of 1 min at room temperature (28-32°C); extraction medium: 1.855 M NaOH; 75.91% ethanol in water and 20.59% hexane in the total volume of the extractant; and FAEE to extractant ratio of 1:10 corresponding to a maximum γ-oryzanol yield of 75.82±3.44% and the desired FAEE yield of 54.42±7.80%. The γ-oryzanol-rich fraction was further purified by washing with a 2% Na2CO3 solution, obtaining 69.94% recovery yield with 89.90% purity of γ-oryzanol. The purified γ-oryzanol showed good scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and the ABTS radical and was comparable to the commercial product, clearly suggesting that the presented process was efficient and feasible.

Injectable sodium pentobarbital: Stability at room temperature

IntroductionSodium pentobarbital (Nembutal) is a barbiturate used in research as an anesthetic in many animal models. The injectable form of this drug has lately become difficult to procure and prohibitively expensive. Due to this lack of availability, researchers have begun to compound injectable sodium pentobarbital from so-called “nonpharmaceutical” pentobarbital. Some oversight agencies have objected to this practice, claiming a lack of quality control and degradation of the drug. We sought with this study to establish both: 1) a protocol for the preparation of injectable sodium pentobarbital, and 2) standard operating procedures to monitor the quality of the preparation and degradation of the drug over time. MethodsOur preparation consists of a mixture of sodium pentobarbital in alkaline aqueous solution, propylene glycol, and ethanol. Pentobarbital content in this preparation was assayed by high-pressure liquid chromatography (HPLC). We also assayed pentobarbital content over time in preparations of various ages up to 6years old. ResultsWe determined that the drug degraded at a maximum of 0.5% per year in our preparation (alkaline water/propylene glycol/ethanol) when stored in the dark at room temperature. A yellow discoloration developed after about 2years, which we have arbitrarily determined disqualifies the preparation from use as an anesthetic. Attempts to spectroscopically assay this discoloration were not successful. ChemicalsPentobarbital sodium (CID: 14075609)

Physicochemical characterization of lignin fractions sequentially isolated from bamboo (Dendrocalamus brandisii) with hot water and alkaline ethanol solution

AbstractNine lignin fractions from bamboo (Dendrocalamus brandisii) were sequentially isolated with hot water at 80, 100, and 120°C for 3 h and 60% aqueous ethanol containing 0.25, 0.5, 1.0, 2.0, 3.0, and 5.0% NaOH at 80°C for 3 h. Molecular weight and purity analysis revealed that the lignin fractions isolated by hot water (L1, L2, and L3) had lower weight‐average molecular weights (between 1350 and 1490 g mol−1) and contained much higher amounts of associated hemicelluloses (between 9.26 and 22.29%), while the lignin fractions isolated by alkaline aqueous ethanol (L4, L5, L6, L7, L8, and L9) had higher weight‐average molecular weights (between 2830 and 3170 g mol−1) and contained lower amounts of associated hemicelluloses (between 0.63 and 1.66%). Spectroscopy (UV, FTIR, 13C‐NMR, and HSQC) analysis showed that the bamboo (Dendrocalamus brandisii) lignin was typical grass lignin, consisting of p‐hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. The major interunit linkages presented in the alkaline aqueous ethanol extractable bamboo lignin were β‐O‐4′ aryl ether linkages (about 74.3%), followed by β‐β′ resinol‐type linkages and β‐1′ spirodienone‐type linkages (both for 7.8%), together with small amounts of β‐5′ phenylcoumaran (6.8%) and p‐hydroxycinnamyl alcohols end groups (3.1%). In addition, a small percentage (1.0%) of the lignin side‐chain was found to be acetylated at the γ‐carbon, predominantly over syringyl units. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Kinetic study of a complex triangular reaction system in alkaline aqueous-ethanol medium using on-line transmission FTIR spectroscopy and BTEM analysis

The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methyl 4-hydrozybenzoate (MP) to form ethyl 4-hydroxybenzoate (EP) as an intermediate and sodium 4-hydroxybenzoate as a final product. The pure component spectra of the reactive species involved in the reaction were reconstructed using BTEM technique. Their corresponding real concentrations were calculated and subsequently used for analyzing the kinetics of this triangular reaction system. The effects of temperature and solvent mixture compositions were studied. In general, the results show that the rates of both hydrolysis and ethanolysis reactions increase with temperature. Addition of ethanol to the solvent mixture also reduces the rates of the hydrolysis reactions. The effect of solvent mixture on the rate of ethanolysis reaction is more complex and influenced by at least two competing factors, namely the concentration of ethoxide ion in the solution and the stabilization effect on the reactant. The enthalpy and entropy activation parameters, ΔH‡ and ΔS‡, of both the hydrolysis and ethanolysis reactions were determined using the Eyring equation and the activation parameters confirm the associative nature in the elementary steps in these reactions. Finally, it is shown that the dominant synthetic pathway in this triangular system changes from direct hydrolysis of methyl 4-hydrozybenzoate to the indirect pathway via ethanolysis and then hydrolysis depending on the solvent mixture composition.

Preparation of Poly(t-butyl methacrylate)-Polyimide Particles by Dispersion Polymerization of t-Butyl Methacrylate Using Poly(amic acid) as a Stabilizer and Subsequent Imidization

Dispersion polymerization of t-butyl methacrylate (BMA) and a cationic comonomer, 4-(vinylbenzyl)trimethylammonium chloride (VBA) was conducted in alkaline aqueous ethanol using various aromatic poly(amic acid)s (PAA) as stabilizers. The monodisperse particles were obtained in high yield using the optimum composition of solvent mixture depending on the PAA structure. By using a cationic comonomer (VBA), PAA was quantitatively incorporated into the particles. The imidization of PAA on the particles proceeded with acetic anhydride and 4-(dimethylamino)pyridine to form PBMA-polyimide (PBMA-PI) particles. The PBMA-PI particles were maintained in spherical shape by the thermal treatment up to 280 °C.

The co-dispersion of silicon carbide with nano-C and B 4C in aqueous ethanol solution

In this paper, the mixture of de-ionized water and ethanol was used as the solvent for SiC particles. SiC can be well co-dispersed in alkaline aqueous ethanol solution with the sintering aids nano-C and B 4C, especially when the pH value is between 9 and 10. Polyethylene glycol (PEG) as the dispersant, it can improve the dispersion of SiC slurry. The adsorption of polyethylene glycol in SiC slurries was measured by thermal gravimetric (TG) and differential thermal analysis (DTA) in argon atmosphere. It was found that the adsorption of polyethylene glycol on the surface of SiC, nano-C and B 4C decreased with the increase of pH value and most free dispersant remained in the suspension at higher pH value. The granulated and flowable powder was prepared by spraying processing.

Preparation of Polystyrene-Polyimide Particles by Dispersion Polymerization of Styrene Using Poly(amic acid) as a Stabilizer

Dispersion polymerization of styrene (S) and a cationic comonomer, 4-(vinylbenzyl)trimethylammonium chloride (VBA) was conducted in alkaline aqueous ethanol using various aromatic poly(amic acid)s (PAA) as stabilizers. The monodisperse particles were obtained in high yield using the optimum composition of solvent mixture depending on the PAA structure. By using a cationic comonomer (VBA), PAA was incorporated quantitatively into the particles. On the other hand, using cationic methacrylates as a comonomer, PAA was not incorporated effectively. The imidization of PAA on the particles proceeded with acetic anhydride and 4-(dimethylamino)pyridine to form PS-polyimide (PS-PI) particles. The PS-PI particles were maintained in spherical shape by the thermal treatment up to 240 °C. PI hollow particles were also obtained by washing PS-PI particles with toluene.

Spectroscopic Characterization of Hydroxide and Aqua Complexes of Fe(II)-Protoheme, Structural Models for the Axial Coordination of the Atypical Heme of Membrane Cytochrome b6f Complexes

Electronic absorption and resonance Raman (RR) spectra are reported for hydroxide and aqua complexes of iron(II)-protoporphyrin IX (Fe(II)PP) respectively formed in alkaline and neutral aqueous solutions. These compounds with weak axial ligand(s) represent a biomimetic approach of the unusual coordination of the atypical heme c(i) of membrane cytochrome b6f complexes. Absorption spectra and spectrophotometric titrations show that Fe(II)PP in alkaline aqueous cetyltrimethylammonium bromide (CTABr) binds one hydroxide ion, forming a five-coordinated high-spin (HS) complex. In alkaline aqueous ethanol, we confirm the formation of a dihydroxy complex of Fe(II)PP. In the RR spectra of Fe(II)PP dissolved in neutral aqueous CTABr, a mixture of a four-coordinated intermediate spin form with an HS monoaqua complex (Fe(II)PP(H2O)) was observed. The spectroscopic information obtained for Fe(II)PP(OH-), Fe(II)PP(H2O), and Fe(II)PP(OH-)2 was compared with that previously reported for the 2-methylimidazole and 2-methylimidazolate complexes of Fe(II)PP, representative of the most common axial ligation in HS heme proteins. This investigation reveals a very remarkable analogy in the spectral properties of, in one hand, the Fe(II)PP(H2O) and mono-2-methylimidazole complexes and, in the other hand, the Fe(II)PP(OH-) and mono-2-methylimidazolate complexes. The comparisons of the absorption and RR spectra of Fe(II)PP(OH-) and Fe(II)PP(OH-)2 clearly establish that both a redshift of the pi-pi electronic transitions and an upshift of the v8 RR frequency are spectral parameters indicative of porphyrin doming in HS ferrous complexes. Based upon isotopic substitutions (16OH-,16OD-, and 18OH-), stretching modes of the Fe-OH bond(s) of a ferrous porphyrin were assigned for the first time, i.e., at 435 cm(-1) for Fe(II)PP(OH-) (nu(Fe(II)-OH-)) and at 421 cm(-1) for Fe(II)PP(OH-)2 (nu(s)(Fe(II)-(OH-)2). The spectroscopic and redox properties of Fe(II)PP(H2O), Fe(II)PP(OH-), and heme c(i) were discussed and favor a water coordination for the heme c(i) iron.

Photocatalytic degradation of lignin and lignin models, using titanium dioxide: the role of the hydroxyl radical

The role of hydroxyl radicals on the degradation of lignins during a cellulosic pulp bleaching process including a photocatalytic stage, was assessed using peroxyformic acid lignins EL1 and REL1 and two phenolic biphenyl lignin models 1 and 2 . The irradiations were performed in the absence of photocatalyst TiO 2 and H 2O 2 (condition a), in the presence of TiO 2 (condition b) and in the presence of H 2O 2 (condition c). The experiments were conducted in alkaline (pH ≈ 11) aqueous ethanol solutions with oxygen bubbling. The relative phenolic content of the irradiated solutions, which is indicative of the involvement of hydroxyl radicals, was determined by ionization absorption spectroscopy. The results obtained show that the catalyzed reaction involves both degradation of the phenolate groups by electron transfer and hydroxylation of the lignin aromatic structure. Benzyl alcohol structural elements in sodium borohydride reduced lignin REL1 and compound 2 were also found as good trapping agents for the hydroxyl radicals. The degradation of EL1 was studied by measuring its fluorescence emission by comparison to the fluorescence of compound 2 . The emission spectra indicate that some biphenyl phenolate anions in EL1 are reacting under UV/visible irradiation and some others, probably polyphenolic chromophores emitting less fluorescence, are formed.

Optimizing multisteps mechanical-chemical fractionation of wheat straw components

Wheat straw was refined into fibres, hemicellulosic sugars and lignin oligomers by means of a multi-stage fractionation treatment: mechanical separation of the botanical components followed by one or two stage chemical fractionation process. Yellow winter wheat straw was initially separated into two fractions by milling in a Disc Mill: (a) chips, containing mostly internodes and (b) meal, consisting mainly of ground leaves and nodes. The internode fraction (63% of the whole straw) contained 8% more cellulose, 9% more lignin and 10% less ash compared with the unfractionated material. Disc mill fractionation was particularly effective with respect to the separation of the non-lignocellulosic components, i.e. protein, extractives, etc. Wheat straw internodes as well as whole straw were treated with acidic or alkaline aqueous ethanol in one or two stages; two-stage treatment involved the introduction of a pretreatment step with dilute acid improving, both, the production of hemicellulose derived sugars, and the aqueous-ethanol delignification to follow. The fibre yield in the case of internode chemical fractionation was generally higher in comparison with the one of the whole straw. The fibrous fractionation residues from internodes were in all cases enriched in cellulose compared with whole straw fibres. In spite of the higher initial lignin content of the internodes, delignification was more extensive than in the case of whole straw. Moreover, variations in the residual lignin composition were found, reflecting the intensity of the chemical fractionation process, as well as the origin of the raw material.

Short Communication: Kinetics and Mechanism of Oxidation of Diallylamine by Alkaline Hexacyanoferrate (III)

The kinetics of oxidation of diallylamine by hexacyanoferrate (III) in alkaline aqueous ethanol at constant ionic strength has been studied. The rate of the reaction was dependent on the first power of the concentration of diallylamine, but was independent of hexacyanoferrate (III) concentration. The rate was enhanced by an increase in the pH value The effects of added hexacyanoferrate (II), ionic strength, types of anion and cation, and the solvent composition have also been investigated. The activation parameters were evaluated. A mechanism consistent with the kinetic results is proposed and discussed.

Alkaline Oxygen Oxidation of Dioxane Lignin and Creosol in Aqueous Ethanol

Abstract The degradation of dioxane lignin with oxygen in alkaline aqueous ethanol was studied. An increase in the ethanol concentration resulted in an accelerated degradation of lignin. Separate experiments with creosol (2-methoxy-4-methylphenol) indicated that this effect can at least partly be ascribed to the inhibition of the coupling of phenoxy radicals, which prevents the recondensation of the lignin fragments.

Electron spin resonance spectroscopy as an analytical tool

Monomethoxy- and dimethoxy-p-benzoquinones have been investigated in alkaline aqueous methanol and ethanol by electron spin resonance spectroscopy. All compounds show solvent exchange of the methoxy group(s). 2,6-Dimethoxy-p-benzoquinone dissolved in aqueous ethanol exhibits spectra of three radicals, due to partial exchange of none, one and two methoxy groups. Computer simulations demonstrate that γ-protons of the ethoxy group(s) give rise to splittings comparable to the linewidths. Monomethoxy-p-benzoquinone undergoes alkoxylation solely leading to the 2,5 analogue.

The conformation of o‐benzosemiquinone radical and its assignment of the proton hyperfine coupling constants by using the indo and the molecular geometry adjusting methods

AbstractThe minimal energy conformations of o‐benzosemiquinone anion radical were calculated for several cases of assignments by using the INDO method and the molecular geometry adjusting method. In order to know the effect of lithium ion in the solvent, the minimal energy conformations of the system of LiOH and o‐benzosemiquinone anion radical were calculated. The calculations of the minimal energy conformations of this radical in t‐butyl alcohol, alkaline aqueous ethanol, alkaline water, neutral methanol, and acetonitrile were carried out. The total energies of the minimal energy conformations in the assignment |A3| > |A4| were lower than those in the assignment |A3| < |A4|.

The role of oxygen in the mechanism of the intramolecular photoredox reaction of Fe III protoporphyrin IX in alkaline aqueous ethanol

The evidence of superoxide formation during the irradiation of FeIII protoporphyrin IX in oxygenated alkaline aqueous ethanol and the very short re-oxidation time of the photoredox FeII porphyrin product are consistent with a photoinduced electron transfer from ethanol to oxygen occurring with the assistance of an FeIII porphyrin ethanolate complex.

Transesterification kinetics of phenyl salicylate

The degradation of phenyl salicylate in alkaline aqueous ethanol is shown to proceed via competing transesterification and hydrolysis processes. The transesterified product, ethyl salicylate, also undergoes hydrolysis, but at a slower rate and a kinetic model is presented which allows the simultaneous determination of all three rate constants. These results are contrasted with those of an earlier literature study and show the necessity for specific assay systems in kinetic analysis.

Photochemical Electron Transport from Water Layer to Organic Layer via Sodium Anthraquinone-2-sulfonate by Stepwise Two Photon Excitation

Abstract Photochemical electron transport from hydroxide ion to organic acceptor molecule via an anthraquinone derivative as an electron carrier was investigated in homogeneous, cationic micellar, and cationic reversed micellar systems. In homogeneous alkaline aqueous ethanol, the photochemically generated radical anion of sodium anthraquinone-2-sulfonate (1) was stable against further irradiation with visible light (λ>450 nm), while the dianion of 1 was reversibly converted to the radical anion by visible light irradiation. The reversible conversion was accelerated by the addition of an organic acceptor molecule such as 1,4-dicyanobenzene. In a cationic hexa-decyltrimethylammonium micellar system, an effective photoreduction of 1 by an electron transfer from hydroxide ion concentrated on the micellar surface to the excited 1 located in the surface area of the micelle was observed. In a reversed micellar system an electron was effectively transported from the water layer to the organic layer; an electron was transfered from hydroxide ion in the water layer incorporated in a benzylhexadecyldimethylammonium reversed micelle to 1 at the micellar surface by irradiation with light of λ=365 nm. Successive visible light irradiation (λ>450 nm) caused an electron ejection from the radical anion of 1 to benzonitrile as a bulk phase solvent. The possibility of the incorporation of carbon dioxide into the acceptor cycle of the electron transport system was also examined. In pyridine solution, carbon dioxide caused the disappearance of the reduced species of 1 on visible light irradiation (λ>450 nm). Trace amounts of dihydropyridinedicarboxylic acid derivatives were obtained.

放射線前照射木材のクラフト蒸解 ＩＩ リグニンおよび炭水化物の挙動

Pre-irradiation of wood in alkaline aqueous ethanol increases kraft pulp yield by up to 1.2 %, as already reported. In order to clarify the mechanism of the pulp yield gain, the behaviors of lignin and carbohydrates during pre-irradiation and cooking were investigated.The results are summarized as follows : 1) γ-Irradiation of guaiacylethane in alkaline agueous ethanol produced 5- (1-hydroxyethyl) -guaicylethane, which is formed by radical coupling between α-hydroxyethyl radical from ethanol and guaiacylethane radical having an unpaired electron at C-5. 5, 5'-Dehydrodiguaiacylethane, which may be a predominant product produced by γ-irradiation in the absence of ethanol, was also detected.2) The yield of vanillin obtained by nitrobenzene oxidation of MWL decreased with an increase of γ-ray dosage. The presence of ethanol during γ-irradiation lessened the extent of this decrease and also the degradation of cellobiose.3) Gel filtration of the products obtained by γ-irradiation of MWL and cellobiose in the presence of 14C-ethanol showed the possible combination between ethanol and MWL or cellobiose.4) Molecular weight distributions of kraft lignin obtained from pre-irradiated beech chips were compared with those obtained from unirradiated chips. This result shows that γ-irradiation in the presence of ethanol decreases the ability of lignin to condense during kraft cooking.