Showing papers on "Acetic acid published in 2008"

An efficient succinic acid production process in a metabolically engineered Corynebacterium glutamicum strain

Abstract: A Corynebacterium glutamicum strain (ΔldhA-pCRA717) that overexpresses the pyc gene encoding pyruvate carboxylase while simultaneously exhibiting a disrupted ldhA gene encoding l-lactate dehydrogenase was investigated in detail for succinic acid production. Succinic acid was shown to be efficiently produced at high-cell density under oxygen deprivation with intermittent addition of sodium bicarbonate and glucose. Succinic acid concentration reached 1.24 M (146 g l−1) within 46 h. The yields of succinic acid and acetic acid from glucose were 1.40 mol mol−1 (0.92 g g−1) and 0.29 mol mol−1 (0.10 g g−1), respectively. The succinic acid production rate and yield depended on medium bicarbonate concentration rather than glucose concentration. Consumption of bicarbonate accompanied with succinic acid production implied that added bicarbonate was used for succinic acid synthesis.

Oxidation of Aniline: Polyaniline Granules, Nanotubes, and Oligoaniline Microspheres

Abstract: Aniline was oxidized with ammonium peroxydisulfate in solutions of strong acid (0.1 M sulfuric acid), weak acid (0.4 M acetic acid), or alkali (0.2 M ammonium hydroxide). The properties of the oxidation products and their morphology are controlled by the initial acidity of the medium and the acidity profile during the oxidation; the acidity increases because sulfuric acid is a byproduct. Conducting polyaniline nanogranules, nanotubes, or nonconducting oligoaniline microspheres were obtained, respectively. FTIR spectra suggest that the oligomers produced by the oxidation of neutral aniline molecules at the beginning of oxidation are similar, regardless of the acidity of the medium. Neutral aniline molecules, prevailing under alkaline conditions, are easily oxidized to aniline oligomers composed of ortho- and para-coupled aniline constitutional units. Ortho-coupled units are further converted by oxidative intramolecular cyclization to phenazines. It is proposed that, in acidic media, N-phenylphenazine units...

Effect of Inhibitors Released during Steam‐Explosion Treatment of Poplar Wood on Subsequent Enzymatic Hydrolysis and SSF

Abstract: Steam-exploded (SE) poplar wood biomass was hydrolyzed by means of a blend of Celluclast and Novozym cellulase complexes in the presence of the inhibiting compounds produced during the preceding steam-explosion pretreatment process. The SE temperature and time conditions were 214 degrees C and 6 min, resulting in a log R(0) of 4.13. In enzymatic hydrolysis tests at 45 degrees C, the biomass loading in the bioreactor was 100 g(DW)/L (dry weight) and the enzyme-to-biomass ratio 0.06 g/g(DW). The enzyme activities for endo-glucanase, exo-glucanase, and beta-glucosidase were 5.76, 0.55, and 5.98 U/mg, respectively. The inhibiting effects of components released during SE (formic, acetic, and levulinic acids, furfural, 5-hydroxymethyl furfural (5-HMF), syringaldehyde, 4-hydroxy benzaldehyde, and vanillin) were studied at different concentrations in hydrolysis runs performed with rinsed SE biomass as model substrate. Acetic acid (2 g/L), furfural, 5-HMF, syringaldehyde, 4-hydroxybenzaldehyde, and vanillin (0.5 g/L) did not significantly effect the enzyme activity, whereas formic acid (11.5 g/L) inactivated the enzymes and levulinic acid (29.0 g/L) partially affected the cellulase. Synergism and cumulative concentration effects of these compounds were not detected. SSF experiments show that untreated SE biomass during the enzymatic attack gives rise to a nonfermentable hydrolysate, which becomes fermentable when rinsed SE biomass is used. The presence of acetic acid, vanillin, and 5-HMF (0.5 g/L) in SSF of 100 g(DW) /L biomass gave rise to ethanol yields of 84.0%, 73.5%, and 91.0% respectively, with respective lag phases of 42, 39, and 58 h.

The Production of Myco-Diesel Hydrocarbons and Their Derivatives by the Endophytic Fungus Gliocladium Roseum (NRRL 50072)

Abstract: An endophytic fungus, Gliocladium roseum (NRRL 50072), produced a series of volatile hydrocarbons and hydrocarbon derivatives on an oatmeal-based agar under microaerophilic conditions as analysed by solid-phase micro-extraction (SPME)-GC/MS. As an example, this organism produced an extensive series of the acetic acid esters of straight-chained alkanes including those of pentyl, hexyl, heptyl, octyl, sec-octyl and decyl alcohols. Other hydrocarbons were also produced by this organism, including undecane, 2,6-dimethyl; decane, 3,3,5-trimethyl; cyclohexene, 4-methyl; decane, 3,3,6-trimethyl; and undecane, 4,4-dimethyl. Volatile hydrocarbons were also produced on a cellulose-based medium, including heptane, octane, benzene, and some branched hydrocarbons. An extract of the host plant, Eucryphia cordifolia (ulmo), supported the growth and hydrocarbon production of this fungus. Quantification of volatile organic compounds, as measured by proton transfer mass spectrometry (PTR-MS), indicated a level of organic substances in the order of 80 p.p.m.v. (parts per million by volume) in the air space above the oatmeal agar medium in an 18 day old culture. Scaling the PTR-MS profile the acetic acid heptyl ester was quantified (at 500 p.p.b.v.) and subsequently the amount of each compound in the GC/MS profile could be estimated; all yielded a total value of about 4.0 p.p.m.v. The hydrocarbon profile of G. roseum contains a number of compounds normally associated with diesel fuel and so the volatiles of this fungus have been dubbed ‘myco-diesel’. Extraction of liquid cultures of the fungus revealed the presence of numerous fatty acids and other lipids. All of these findings have implications in energy production and utilization.

Quantitative reconstruction of the nonvolatile sensometabolome of a red wine.

Abstract: The first comprehensive quantitative determination of 82 putative taste-active metabolites and mineral salts, the ranking of these compounds in their sensory impact based on dose-over-threshold (DoT) factors, followed by the confirmation of their sensory relevance by taste reconstruction and omission experiments enabled the decoding of the nonvolatile sensometabolome of a red wine. For the first time, the bitterness of the red wine could be demonstrated to be induced by subthreshold concentrations of phenolic acid ethyl esters and flavan-3-ols. Whereas the velvety astringent onset was imparted by three flavon-3-ol glucosides and dihydroflavon-3-ol rhamnosides, the puckering astringent offset was caused by a polymeric fraction exhibiting molecular masses above >5 kDa and was found to be amplified by the organic acids. The perceived sourness was imparted by l-tartaric acid, d-galacturonic acid, acetic acid, succinic acid, l-malic acid, and l-lactic acid and was slightly suppressed by the chlorides of potass...

A Novel Sulfonated Carbon Composite Solid Acid Catalyst for Biodiesel Synthesis

Abstract: A novel sulfonated carbon composite solid acid was successfully prepared by the pyrolysis of a polymer matrix impregnated with glucose followed by sulfonation. The title catalyst has higher acid site density, better esterification activity of both small and large free fatty acids (acetic acid and palmitic acid), and better reusability than the previously reported carbon-based catalyst prepared by sulfonating pyrolyzed sugar. This catalyst also exhibited higher esterification activity than tungstated zirconia (WZ) and Silica-Supported Nafion (Nafion®SAC-13). The higher activity of the sulfonated carbon composite solid acid catalyst was clearly due to the presence of a much higher acid site density than any of the other catalysts.

Sensors for 5-hydroxytryptamine and 5-hydroxyindole acetic acid based on nanomaterial modified electrodes

Abstract: Simultaneous voltammetric determination of serotonin and 5-hydroxyindole acetic acid has been described at single walled carbon nanotube modified glassy carbon electrode and gold nanoparticles modified indium tin oxide electrode. The method described is fast, simple, accurate with detection limits as low as 32 nM for 5-hydroxytryptamine (5-HT) at single-walled carbon nanotube modified glassy carbon electrode and 27 nM for 5-hydroxyindole acetic acid (5-HIAA) at gold nanoparticles modified indium tin oxide electrode. Linear variation of peak current with change in concentration was observed in the concentration range 0.1–100 μM for 5-HT and 5-HIAA. Application of the method for non-invasive determination of the compounds in urine samples has also been described. The inter- and intra-day stability of the electrodes were also determined and electrodes were found to be sufficiently stable for 1 week.

Production of electrospun gelatin nanofiber by water-based co-solvent approach.

Abstract: In this study, gelatin, was successfully electrospun from a newly developed water-based co-solvent composed of ethyl acetate and acetic acid in water. Since natural polymers including gelatin exhibit limited solubility in water, toxic or highly acidic solvents are normally used to dissolve them for electrospinning. Instead of using those solvents, we used ethyl acetate in concert with acetic acid in water, and investigated the beneficial effect of its use in terms of the spinnability of the nanofiber and the acidity of the solvent. The replacement of acetic acid with ethyl acetate was observed to improve the spinnability of the nanofiber by reducing the surface tension of the solution as well as to increase the pH of the solvent significantly. The optimal composition of the co-solvent was found to correspond to a ratio of ethyl acetate to acetic acid of 2:3. Under this solvent condition, the gelatin could be dissolved at concentrations of up to approximately 11 wt% and electrospun successfully to produce nanofibers with various diameters (47-145 nm on average) depending on the gelatin concentration. The water-based co-solvent method proposed herein may be useful for generating other nanofibrous natural polymers as well as being applicable in delivery systems for bioactive molecules within the nanofiber matrices.

Ageing of Mineral Oil Impregnated Cellulose by Acid Catalysis

Abstract: Acid catalyzed ageing of oil impregnated kraft paper has been studied experimentally. Five different carboxylic acids (formic, acetic, laevulinic, stearic and naphtenic acid) have been added to mineral oil to arrive at a neutralization value of 0.4 mg KOH/g. Thereafter, kraft paper of two different humidities has been allowed to equilibrate with the oil. The results show that the lower the molecular weight of the carboxylic acids is the more is absorbed by the paper. Furthermore, a clear synergy for the paper ageing rates between moisture and the lower molecular weight acids is found, while for the higher molecular weight acids almost no effects were found. It is concluded that present techniques for measuring acidity of oils do not reflect these detailed conditions. It is suggested to introduce a new measuring technique for neutralization value where water rinsing is used to identify the content of low molecular weight, water soluble acids.

Epoxidation of Canola Oil with Hydrogen Peroxide Catalyzed by Acidic Ion Exchange Resin

Abstract: Canola oil with an iodine value of 112/100 g, and containing 60% oleic acid and 20% linoleic acid, was epoxidised using a peroxyacid generated in situ from hydrogen peroxide and a carboxylic acid (acetic or formic acid) in the presence of an acidic ion exchange resin (AIER), Amberlite IR 120H. Acetic acid was found to be a better oxygen carrier than formic acid, as it produced about 10% more conversion of ethylenic unsaturation to oxirane than that produced by formic acid under otherwise identical conditions. A detailed process developmental study was then performed with the acetic acid/AIER combination. The parameters optimised were temperature (65 °C), acetic acid to ethylenic unsaturation molar ratio (0.5), hydrogen peroxide to ethylenic unsaturation molar ratio (1.5), and AIER loading (22%). An iodine conversion of 88.4% and a relative conversion to oxirane of 90% were obtained at the optimum reaction conditions. The heterogeneous catalyst, AIER, was found to be reusable and exhibited a negligible loss in activity.

Hydrogen production via steam reforming of bio-oil components over calcium aluminate supported nickel and noble metal catalysts

Abstract: Steam reforming of two representative bio-oil components, acetic acid and acetone, was investigated thermally and catalytically over nickel (5 wt%) and noble metal (0.5 wt% Rh or Ir) catalysts supported on calcium aluminates (CaO·2Al2O3 and 12CaO·7Al2O3). The thermal reactions (with or without water) were studied in the presence of inert quartz particles and showed that at 750 °C, acetone and to a lesser extent acetic acid undergo a series of homogeneous reactions forming CO, CO2, CH4 and H2 in concentrations which depend on the organic, and the presence or absence of water. Characteristic of acetone thermal steam reforming is that high amounts of acetic acid are produced. The catalysts prepared were tested at three reaction temperatures 550–650–750 °C using steam/carbon = 3 and space velocities around 30 000 h−1. The results showed that acetic acid is easily reformed over the catalysts to hydrogen rich gas with yield approaching that of equilibrium. Hydrogen yields depend on the metal type and loading and the ratio of CaO to Al2O3 of the support. The best performance in terms of highest hydrogen yield is achieved with the 5 wt% Ni/CaO·2Al2O3 catalyst, while the 0.5 wt% Rh/CaO·2Al2O3 catalyst presents the highest resistant to coking. These catalysts were tested in acetone reforming showing also very high activity, low coking deposition rate and slight superiority of the Rh catalyst in terms of hydrogen yield.

Reaction Pathway to the Synthesis of Anatase via the Chemical Modification of Titanium Isopropoxide with Acetic Acid

Abstract: Anatase nanoparticles were obtained through a modified sol–gel route from titanium isopropoxide modified with acetic acid in order to control hydrolysis and condensation reactions. The modification of Ti(OiPr)4 with acetic acid reduces the availability of groups that hydrolyze and condense easily through the formation of a stable complex whose structure was determined to be Ti(OCOCH3)(OiPr)2 by means of FTIR and 13C NMR. The presence of this complex was confirmed with FTIR in the early stages of the process. A doublet in 1542 and 1440 cm−1 stands for the asymmetric and symmetric stretching vibrations of the carboxylic group coordinated to Ti as a bidentate ligand. The gap of 102 cm−1 between these signals suggests that acetate acts preferentially as a bidentate rather than as a bridging ligand between two titanium atoms. The use of acetic acid as modifier allows the control of both the degree of condensation and oligomerization of the precursor and leads to the preferential crystallization of TiO2 in the ...

An array-based study of reactivity under solvent-free mechanochemical conditions—insights and trends

Abstract: An array-based approach is put forward to obtain insight into reactivity under mechanochemical solvent-free conditions. We describe a survey of sixty potential reactions between twelve metal salts MX2 {(M = Cu, X2 = (OAc)2, (HCO2)2, (F3CCO2)2, (acac)2, (F6acac)2, (NO3)2, SO4; M = Ni, X2 = (OAc)2, (NO3)2, SO4; M = Zn, X2 = (OAc)2, (NO3)2} and five bridging organic ligands {isonicotinic acid (HINA), 1,4-benzenedicarboxylic acid (H2BDC), acetylenedicarboxylic acid (H2ADC), 1,3,5-benzenetricarboxylic acid (H3BTC), 4,4′-bipyridyl (BIPY). Reaction conditions involved a ball mill, applied for 15 min at 30 Hz, without external heating. When examined by XRPD, forty of the combinations gave detectable reactions, thirty-eight with crystalline products. Of these, twenty-nine reactions were quantitative (consuming all of at least one reactant). Comparison of XRPD patterns with patterns simulated from single crystal X-ray diffraction data in the Cambridge Structural Database allowed structural identification of six products. Of particular interest are the microporous framework materials [Cu(INA)2] and [Cu3(BTC)2] (HKUST-1) obtained by reaction of the corresponding carboxylic acids with copper acetate. Other non-porous polymers with 3-dimensional connectivity, [Ni(ADC)(H2O)4], or 1-dimensional connectivity, [Cu(acac)2(BIPY)] and [Cu(F6acac)(BIPY)] were also obtained. Reaction between zinc acetate and H2ADC gave a new product which had not previously been characterised by single-crystal X-ray crystallography, but whose XRPD pattern suggests that it is isostructural with the known nickel polymer [Ni(ADC)(H2O)4]. Two further isostructural nickel and zinc products were obtained in reactions between HINA and nickel nitrate and zinc nitrate. Trends observed within the array are discussed. Copper acetate and copper formate were the most effective starting materials for reaction with carboxylic acids, potentially related to the basicity of their anions and the solvating effects of the formic and acetic acid byproducts. Amongst the ligands there was a general negative corelation between melting point and reactivity. The issue of pore templating in microporous phases and the generation of new structures is also discussed in relation to the Cu(INA)2, Cu3(BTC)2 and nickel nitrate-BIPY systems. Overall, the study suggests that mechanochemical reactivity between metal salts and organic ligands under solvent free conditions is remarkably general. Use of array-based approaches as demonstrated here is advocated a useful way to reveal underlying trends in reactivity under solvent free mechanochemical conditions and to highlight particular cases for more detailed study.

Production of ethanol from methanol

Abstract: A process for converting methanol to ethanol which comprises reacting methanol and carbon monoxide in the presence of a catalyst to produce a product comprising at least 25 mole % methyl acetate and, in some instances, acetic acid. The acetic acid then is reacted with at least one alcohol to produce at least one acetate selected from methyl acetate, ethyl acetate, and butyl acetate. The at least one acetate (if produced) and the methyl acetate produced as a result of reacting methanol and carbon monoxide then are hydrogenated to produce ethanol. Syngas may be produced from biomass to produce all or a portion of the methanol, hydrogen, and carbon monoxide requirements for the process.