Showing papers on "Acetic acid published in 1996"
TL;DR: Data indicate that plant cells are able to modulate over a large range their auxin content by modifying the activity of each carrier, and the relative contributions of diffusion and carrier-mediated influx and efflux to the membrane transport of 2,4-D, 1-NAA, and IAA have been quantified.
Abstract: Accumulation of radiolabelled naphthalene-1-acetic acid (1-NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and indole-3-acetic acid (IAA) has been measured in suspension-cultured tobacco (Nicotiana tabacum) cells. In this paper is presented a simple methodology allowing activities of the auxin influx and efflux carriers to be monitored independently by measuring the cellular accumulation of [3H]NAA and [14C]2,4-D. We have shown that 1-NAA enters cells by passive diffusion and has its accumulation level controlled by the efflux carrier. By contrast, 2,4-D uptake is mostly ensured by the influx carrier and this auxin is not secreted by the efflux carrier. Both auxin carriers contribute to IAA accumulation. The kinetic parameters and specificity of each carrier have been determined and new information concerning interactions with naphthylphthalamic acid, pyrenoylbenzoic acid, and naphthalene-2-acetic acid are provided. The relative contributions of diffusion and carrier-mediated influx and efflux to the membrane transport of 2,4-D, 1-NAA, and IAA have been quantified, and the data indicate that plant cells are able to modulate over a large range their auxin content by modifying the activity of each carrier.
396 citations
TL;DR: The lower-range values of the theoretically calculated yields of glycerol were in good agreement with the experimental yields, which may indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential.
Abstract: To prevent the loss of raw material in ethanol production by anaerobic yeast cultures, glycerol formation has to be reduced. In theory, this may be done by providing the yeast with amino acids, since the de novo cell synthesis of amino acids from glucose and ammonia gives rise to a surplus of NADH, which has to be reoxidized by the formation of glycerol. An industrial strain of Saccharomyces cerevisiae was cultivated in batch cultures with different nitrogen sources, i.e., ammonium salt, glutamic acid, and a mixture of amino acids, with 20 g of glucose per liter as the carbon and energy source. The effects of the nitrogen source on metabolite formation, growth, and cell composition were measured. The glycerol yields obtained with glutamic acid (0.17 mol/mol of glucose) or with the mixture of amino acids (0.10 mol/mol) as a nitrogen source were clearly lower than those for ammonium-grown cultures (0.21 mol/mol). In addition, the ethanol yield increased for growth on both glutamic acid (by 9%) and the mixture of amino acids (by 14%). Glutamic acid has a large influence on the formation of products; the production of, for example, alpha-ketoglutaric acid, succinic acid, and acetic acid, increased compared with their production with the other nitrogen sources. Cultures grown on amino acids have a higher specific growth rate (0.52 h-1) than cultures of both ammonium-grown (0.45 h-1) and glutamic acid-grown (0.33 h-1) cells. Although the product yields differed, similar compositions of the cells were attained. The NADH produced in the amino acid, RNA, and extracellular metabolite syntheses was calculated together with the corresponding glycerol formation. The lower-range values of the theoretically calculated yields of glycerol were in good agreement with the experimental yields, which may indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential.
360 citations
TL;DR: In this article, a solution method for the pervaporation separation of acetic acid-water mixtures was proposed, in which dry PVA films were crosslinked by immersion for two days at 40°C in reaction solutions which contained different contents of GA, acetone and a catalyst, HCl.
357 citations
TL;DR: Chitosan films were acylated under heterogeneous conditions in methanol with acetic and hexanoic anhydrides and characterized by proton nuclear magnetic resonance, elemental analysis, and multiple internal reflective Fourier transform infrared spectroscopy as discussed by the authors.
Abstract: Chitosan films were acylated under heterogeneous conditions in methanol with acetic and hexanoic anhydrides and characterized by proton nuclear magnetic resonance, elemental analysis, and multiple internal reflective Fourier transform infrared spectroscopy. The disappearance of the NH2 vibrational band at 1590 cm-1, the appearance of the amide II band at 1555 cm-1, and the relatively low intensity of the ester band at 1735 cm-1 showed that acylation at the surface was site-selective for the amino (N) functionalities. Furthermore, N-acylation at the surface region appeared complete within 1 h. The acylated chitosan films were fractionated in aqueous acetic acid for compositional analysis. Acetylation of chitosan films for 3 h gave 52% of aqueous acetic acid insoluble chitin (outer film region) and 48% unreacted chitosan. In contrast, 3 h hexanoylation reactions resulted in 99% aqueous acetic acid soluble product. Thus, film N-acetylation was more rapid than N-hexanoylation. Moreove...
251 citations
TL;DR: Cells of the yeast Saccharomyces cerevisiae IGC 4072 grown in medium with acetic acid produced a mediated transport system that behaved as an electroneutral proton symport for the anionic form of the acid, subject to repression by glucose, fructose, sucrose, maltose or galactose.
Abstract: Cells of the yeast Saccharomyces cerevisiae IGC 4072 grown in medium with acetic acid produced a mediated transport system for acetic acid that behaved as an electroneutral proton symport for the anionic form of the acid. The system could transport propionate and formate but not lactate and pyruvate. Uptake of labelled lactic acid was negligible, no mediated transport system activity for this acid being found. The acetate transporter was also found in cells grown in lactic acid or ethanol media, suggesting that the carrier did not require the presence of an external inducer. When cells were grown in lactic acid medium, uptake of labelled acetic acid, at pH 5.0, was biphasic and consistent with the presence of two distinct transport modes for the acid. One of these components corresponded to the acetate/proton symport, and the higher affinity system corresponded to a more general monocarboxylate carrier that could also transport lactate, pyruvate and propionate. Both systems were subject to repression by glucose, fructose, sucrose, maltose or galactose. In glucose-repressed cells, the undissociated form of the acids appeared to be the only one that could cross the plasma membrane, a diffusion mechanism being involved in the acid uptake. Under these growth conditions and when the extracellular pH was lower than that of the cytosol, accumulation of the acid could also be observed, it being a function of the delta pH.
190 citations
TL;DR: Strain TT4B has been isolated from anaerobic sediments known to be contaminated with a variety of organic solvents and grew anaerobically with acetate as the electron donor and tetrachloroethylene as the electrons acceptor in a mineral medium.
Abstract: Strain TT4B has been isolated from anaerobic sediments known to be contaminated with a variety of organic solvents. It is a gram-negative, rod-shaped bacterium and grew anaerobically with acetate as the electron donor and tetrachloroethylene as the electron acceptor in a mineral medium. cis-Dichloroethylene was the halogenated product. This strain did not grow fermentatively and used only acetate or pyruvate as electron donors. Tetrachloroethylene and trichloroethylene were used as electron acceptors, as were ferric nitriloacetate and fumarate. Nitrogen and sulfur oxyanions were not able to substitute as the electron acceptor for this organism. Modest growth occurred in a two-phase system with 1 ml of hexadecane containing 50 to 200 mM tetrachloroethylene (aqueous concentrations, 25 to 100 microM) and 10 ml of anaerobic mineral solution with Na2S as the reducing agent. Growth was completely inhibited at tetrachloroethylene levels above 100 microM.
188 citations
Patent•
22 Mar 1996TL;DR: In this paper, a method is provided to improve the quality of recycle of certain residues by modifying the separation of alkanes and alkane-like materials and carbonyl-containing impurities from the recycle during the manufacture of acetic acid by the carbonylation of methanol.
Abstract: A method is provided to improve the quality of recycle of certain residues by modifying the separation of alkanes and alkane-like materials and carbonyl-containing impurities from the recycle during the manufacture of acetic acid by the carbonylation of methanol. The improvement comprises partitioning the residues by the addition of water obtained from aqueous streams containing up to 50 wt.% acetic acid and which have been treated in a catalytic distillation unit to react the acetic acid with methanol to form recyclable methyl acetate and water and wherein the water is separated from the organics by distillation.
187 citations
TL;DR: In this article, the formation of acids from aldehydes in photocatalytic oxidation is different from known homogeneous chemistry and demonstrates the ability of the solid surface to stabilize energized transient species.
Abstract: The kinetics of photocatalytic oxidation of ethanol has been studied, and the formation and destruction rates of products have been measured. The important intermediates were identified as acetaldehyde, acetic acid, formaldehyde, and formic acid. Minor reaction channels resulted in the formation of methyl formate, ethyl formate, and methyl acetate. Kinetic and “dark” adsorption parameters were measured for ethanol and all of the important intermediates. We have modeled the complete oxidation process using a sequential chemical reaction mechanism. This mechanism is based primarily upon known homogeneous chemistry. However, the formation of acids from aldehydes in photocatalytic oxidation is different from known homogeneous chemistry and demonstrates the ability of the solid surface to stabilize energized transient species. We have measured the adsorp tion isotherms for ethanol and the oxidized intermediates and have concluded that there are two adsorption sites for some of the chemical species. We think it...
183 citations
TL;DR: Ru, Pt and Rh catalysts supported on titania, ceria or active carbon and a Mn/Ce composite oxide catalysts were prepared and their catalytic behavior in Wet Air Oxidation (20 bar O 2 ) of phenol and acetic acid were investigated.
181 citations
TL;DR: The volatile compounds extracted from both traditional and industrial chorizo-a dry fermented sausage-were analysed by gas chromatography/mass spectrometry, and most of the volatiles increased during ripening, especially acids, alcohols, esters, phenols, ketones and terpenes.
161 citations
TL;DR: It was found that the autoclaved yeast cells and ethanol produced by yeasts were helpful forAcetobacterto grow or produce acetic acid and the symbiosis phenomenon between the yeast and Acetobacter was studied.
TL;DR: In this paper, a complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed, which can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.
Abstract: Computer simulation showed that catalytic distillation is an attractive process for the removal of dilute acetic acid from wastewater. Selection of catalysts and kinetic data have been obtained for the design of the catalytic distillation column.
Kinetic measurements were conducted in a batch reactor. Methanol was added to the dilute acetic acid solutions and reacted with the acid in water to form methyl acetate and water. The reaction can be catalyzed by solid acid catalysts. It was found that Amberlyst 15 was an effective catalyst for this reaction. The effects of stirrer speed, reaction temperature, reactant concentration and catalyst loading on reaction rate were investigated. A complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed. This equation can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.
TL;DR: The shift of charge states of oligonucleotide negative ions formed in electrospray ionization mass spectrometry to higher mass-to-charge ratio has been accomplished by addition of organic acids and bases to the solution as mentioned in this paper.
TL;DR: In this article, low-rank coals using hydrogen peroxide at low temperature under ambient pressure is a promising method of producing small molecule fatty acids in high yield and in high selectivity.
Abstract: Oxidation of low-rank coals using hydrogen peroxide at low temperature under ambient pressure is a promising method of producing small molecule fatty acids in high yield and in high selectivity. Five low-rank coals (C% = 65.1−74.7 on daf basis) served to test the validity of the method. When Argonne Premium Beulah Zap lignite was oxidized with 20 volumes of 30% H2O2 aqueous solution for 24 h at 60 °C, the carbon conversion to water-soluble organics reached 0.71. About a half of the water-soluble organics were small molecules: methanol, formic acid, acetic acid, glycolic acid, and malonic acid. The high yields of these compounds are closely related to the structure of low-rank coals. Obtaining these products in such high yield and high selectivity under mild reaction conditions may give us a new route for utilizing low-rank coals.
TL;DR: In this paper, a benzamidines were prepared from benzonitriles in good yield via catalytic hydrogenation of intermediate benzamideoximes in acetic acid/acetic anhydride.
TL;DR: In this paper, it was shown that in the presence of several equivalents of Cl- and I- ions, catalyzed the direct formation of methanol and acetic acid from methane, carbon monoxide, and dioxygen at 80−85 °C in a 6:1 mixture of perfluorobutyric acid and water (approximate turnover rate: 2.9/h based on Rh).
Abstract: RhCl3, in the presence of several equivalents of Cl- and I- ions, catalyzed the direct formation of methanol and acetic acid from methane, carbon monoxide, and dioxygen at 80−85 °C in a 6:1 mixture of perfluorobutyric acid and water (approximate turnover rate: 2.9/h based on Rh). It was possible to selectively form either methanol or acetic acid by a simple change in the solvent system. As might be anticipated, ethane was more reactive than methane, and under similar reaction conditions formed methanol, ethanol, and acetic acid (approximate turnover rate: 7.5/h based on Rh). For both methane and ethane, the product alcohols were less reactive than the starting alkanes. Methyl iodide was also less reactive than methane. Most significantly, for ethane and higher alkanes products derived from C−C cleavage dominated over those derived from C−H cleavage on a per bond basis. Indeed, C−C cleavage products were virtually all that were observed with butane, isopentane, and 2,3-dimethylbutane. While the mechanism...
TL;DR: In this article, the results of two forest soil samples from the German Environmental Specimen Bank (DEBS) were presented, and the results indicated that reducible oxides and organics retained the major mobile fraction of the elements investigated.
TL;DR: In this paper, a three-step process was used to extract 20% of the total Eicosapentaenoic acid (EPA) from the marine microalgae Phaeodactylum tricornutum.
Abstract: Eicosapentaenoic acid (EPA, 20∶5n-3) was obtained from the marine microalgaePhaeodactylum tricornutum by a three-step process: fatty acid extraction by direct saponification of biomass, polyunsaturated fatty acid (PUFA) concentration by formation of urea inclusion compounds, and EPA isolation by semipreparative high-performance liquid chromatography (HPLC). Alternatively, EPA was obtained by a similar two-step process without the PUFA concentration step by the urea method. Direct saponification of biomass was carried out with two solvents that contained KOH for lipid saponification. An increase in yield was obtained because the problems associated with emulsion formation were avoided by separating the biomass from the soap solution before adding hexane for extraction of insaponifiables. The most efficient solvent, ethanol (96%) at 60°C for 1 h, extracted 98.3% of EPA. PUFA were concentrated by the urea method with a urea/fatty acid ratio of 4∶1 at a crystallization temperature of 28°C and by using methanol and ethanol as urea solvents. An EPA concentration ratio of 1.73 (55.2∶31.9) and a recover yield of 78.6% were obtained with methanol as the urea solvent. This PUFA concentrate was used to obtain 93.4% pure EPA by semipreparative HPLC with a reverse-phase, C18, 10 mm i.d.×25-cm column and methanol/water (1% acetic acid), 80∶20 w/w, as the mobile phase. Eighty-five percent of EPA loaded was recovered, and 65.7% of EPA present inP. tricornutum biomass was recovered in highly pure form by this three-step downstream process. Alternatively, 93.6% pure EPA was isolated from the fatty acid extract (without the PUFA concentration step) with 100% EPA recovery yield. This two-step process increases the overall EPA yield to 98.3%, but it is only possible to obtain 20% as much EPA as that obtained by three-step downstream processing.
TL;DR: In this article, the respiratory denitrification activity of activated sludge bacteria with different carbon sources (acetic acid, crude syrup, hydrolyzed starch, methanol) was studied in long-term continuous cultivations and batch tests.
TL;DR: In this article, a series of adsorbents, known as good catalysts for the selective hydrogenation of carboxylic acids to corresponding aldehydes, were studied.
TL;DR: In this paper, catalytic wet-air oxidation of aqueous solutions (5 g · l−1) of car-ylic acids (formic, oxalic, and maleic) was carried out with air at 293-463 K on carbon-supported platinum catalysts.
Abstract: Catalytic wet-air oxidation (CWAO) of aqueous solutions (5 g · l−1) of car☐ylic acids (formic, oxalic, and maleic) was carried out with air at 293–463 K on carbon-supported platinum catalysts. Platinum was loaded on active charcoal by cationic exchange, then reduced under H2. Homogeneous dispersions of 1–2 nm metal particles were obtained. CWAO reactions were performed at 1 or 15 bar air pressure in stirred, batch reactors. Total conversion of formic and oxalic acids into carbon dioxide was obtained under very mild conditions (air at atmospheric pressure, 326 K). The Pt/C catalyst was almost inactive for the oxidation of acetic acid but maleic acid was oxidized under moderate conditions (15 bar of air pressure, 405 K) which indicates that the degradation of this acid does not occur via acetic acid.
TL;DR: It was concluded that in Z. bailii, ethanol plays a protective role against the possible negative effects of acetic acid by inhibiting its transport and accumulation, and the intracellular concentration of the acid could be maintained at levels lower than those expected if the acid entered the cells only by simple diffusion.
Abstract: Cells of Zygosaccharomyces bailii ISA 1307 grown in a medium with acetic acid, ethanol, or glycerol as the sole carbon and energy source transported acetic acid by a saturable transport system. This system accepted propionic and formic acids but not lactic, sorbic, and benzoic acids. When the carbon source was glucose or fructose, the cells displayed activity of a mediated transport system specific for acetic acid, apparently not being able to recognize other monocarboxylic acids. In both types of cells, ethanol inhibited the transport of labelled acetic acid. The inhibition was noncompetitive, and the dependence of the maximum transport rate on the ethanol concentration was found to be exponential. These results reinforced the belief that, under the referenced growth conditions, the acid entered the cells mainly through a transporter protein. The simple diffusion of the undissociated acid appeared to contribute, with a relatively low weight, to the overall acid uptake. It was concluded that in Z. bailii, ethanol plays a protective role against the possible negative effects of acetic acid by inhibiting its transport and accumulation. Thus, the intracellular concentration of the acid could be maintained at levels lower than those expected if the acid entered the cells only by simple diffusion.
TL;DR: If POME is used for PHA production, a pH should be maintained at 7 in the anaerobic sludge treatment step, so that no formic acid is produced which would affect the maximum yield of PHA.
TL;DR: In this paper, the authors developed models for two samples of Swiss cheese which differed in their ripening stage and flavour profile, based on an unripened, freeze-dried cheese of the Mozzarella type.
Abstract: Flavour models were developed for two samples (A and B) of Swiss cheese which differed in their ripening stage and flavour profile. The models were based on an unripened, freeze-dried cheese of the Mozzarella type. Compounds which, in previous studies had been screened as contributors to the odour and taste of Swiss cheese, were added to the base in various combinations and at concentrations equal to those found in Swiss cheeses A and B. Models composed of methional, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, acetic acid, propionic acid, lactic acid, succinic acid, glutamic acid, sodium, potassium, calcium, magnesium, ammonium, phosphate and chloride were judged to meet the flavour of Swiss cheese very well.
TL;DR: The thermally-induced conversion of chitosonium acetate in film form into a water-insoluble chitin film was examined by thermal analysis (DMTA, TGA, DSC, and TMA) and by solid state 13C-NMR spectroscopy as mentioned in this paper.
Abstract: The water-soluble solids comprised of the ionic complex between chitosan and acetic acid, chitosonium acetate, are converted into chitin by heating. The thermally-induced conversion of a water-soluble chitosonium acetate in film form into a water-insoluble chitin film was examined by thermal analysis (DMTA, TGA, DSC, and TMA) and by solid state 13C-NMR spectroscopy. Results indicate that tan δ-transitions occur at increasingly high temperatures, and over progressively wider temperature ranges, as the transformation progresses. Likewise, the storage modulus, log E′, increases as the chitosonium acetate film undergoes “cure” and converts to chitin. Cure kinetic parameters are obtained using the model proposed by Provder et al. modified for glass transition temperature (Tg). The results suggest the existence of two sequential first order reactions, an initial and a late cure reaction, having activation energies of approximately 15 and 21 kcal/mol, respectively. © 1996 John Wiley & Sons, Inc.
TL;DR: In this paper, a chiral modifier, (R)-1-(1-naphthyl)ethylamine, has been tested in the enantioselective hydrogenation of ethyl pyruvate to ethyl lactate over 5 wt% Pt/Al2O3.
TL;DR: In this article, the chemical reactions underlying the formation of a water-based alkoxide sol gel solution for lead zirconate titanate thin films have been evaluated using infra-red spectroscopy and viscosity measurements.
Abstract: The chemical reactions underlying the formation of a water based alkoxide sol gel solution for lead zirconate titanate thin films have been evaluated using infra-red spectroscopy and viscosity measurements. Titanium isopropoxide and zirconium propoxide are modified by acetic acid in order to use water as a solvent. Substitution reactions initially take place with the formation of titanium or zirconium alkoxide acetate and alcohol. The titanium or zirconium alkoxide acetate gradually associate through the formation of M-O-M linkages to increase the viscosity of the solution.
TL;DR: In this paper, the conductance of SDS in water in the presence of pyridine and acetic acid at temperatures between 15 and 45 °C has been measured and from the conductivity data, the critical micellar concentration (cmc), degree of counter-ion association (α), molar conductivities at infinite dilution (Λ0) and free energy of transfer of the surfactant hydrocarbon chain from medium to the micelle (FEC) have been computed.
Abstract: The conductances of sodium dodecyl sulfate (SDS) have been determined in water in the presence of various additives, such as strong nitrogen organic bases (pyridine, 3- and 4-methylpyridines, and 2,6-dimethylpyridine), carboxylic acids (acetic acid, propionic acid, and butyric), and alcohols (methanol (MeOH), 1-butanol (BuOH), 2-methyl-1-propanol, 2-methyl-2-propanol, and 2-methyl-2-butanol) at 25 °C. The conductances of SDS in water in the presence of pyridine and acetic acid at temperatures between 15 and 45 °C have also been measured. From the conductivity data, the critical micellar concentration (cmc), degree of counter-ion association (α), molar conductivities at infinite dilution (Λ0), limiting ionic molar conductivities (), free energy of transfer of the surfactant hydrocarbon chain from medium to the micelle (), free energy of transfer of surface contributions (), and standard enthalpies of micellisation () of SDS have been computed. It has been found that the presence of strong nitrogen organic ...
TL;DR: In this article, a one-pot, three-step procedure was developed for the synthesis of peracetylated glycal derivatives from various reducing sugars including D-glucose, D-galactose, L-rhamnose and L-arabinose.
Patent•
01 Mar 1996TL;DR: In this paper, the authors proposed a method for administering chemical compositions to patients and to medical aids for the treatment and prevention of blood and other disorders, which can be used to treat or prevent the symptoms associated with anemia, sickle cell diseases, thalassemia and other blood disorders.
Abstract: The invention relates to compositions containing chemical compounds having the structure R1-C(O)-R2-R3, phenyl-R5-R6-R7 or phenyl-R9-R10 wherein: R1 is SH2, NH2 or OH; R2 is a branched or linear alkyl; R3 is CONH2, COSH, COOH, COOR4, C(O)R4 or OR4; R4 is a branched or linear alkyl; R5 is O, SH or NH; R6 is a branched or linear alkyl; R7 is COOH, CONH2, COSH, COOR8, C(O)R8 or OR8; R8 is a branched or linear alkyl; R9 is a branched alkyl of 2 to 4 carbon atoms or an unbranched alkyl of 2 or 4 carbon atoms; R10 is COOH, CONH2, COSH, COOR11, C(O)R11 or OR11; and R11 is a branched or linear alkyl, e.g. cinnamic acid, hydrocinnamic acid, alpha-methyl hydrocinnamic acid, phenoxy acetic acids and amides, thiophenoxy acetic acid and acid amide, thiophenoxy propionic acid, thiophenoxy butyric acid, methoxy acetic acid, phenyl butyric acid, fumaric acid, fumaric acid monoamide and diamide, fumaric acid monoethyl ester, succinic acid, succinic acid monoamide (succinamic acid), succinic acid diamide (succinamide), ethyl phenyl acetate, acids and amides of butyric acid ethyl ester, trifluorobutyric acid, tributyrin, ethyl-phenyl acetic acid, indol-3-butyric acid and indol-3-propionic acid and compositions containing steel factor. The compositions stimulate the expression of hemoglobin or globin protein such as embryonic or fetal globin, or the proliferation of hemoglobin expressing and other cells. These compositions can be used to treat or prevent the symptoms associated with anemia, sickle cell diseases, thalassemia and other blood disorders. The invention also relates to methods for administering these compositions to patients and to medical aids for the treatment and prevention of blood and other disorders.