Showing papers on "Acetic acid published in 1983"

Aqueous-phase source of formic acid in clouds

Abstract: The coupled gas- and aqueous-phase cloud chemistry of HCOOH were examined for controlling factors in the acidity of cloud and rainwater. Attention was given to the aqueous OH/HO2 system that yields an OH species that is highly reactive with other species, notably SO2 and the formaldehyde/formic acid complex. A numerical model was developed to simulate the cloud chemistry in the remote troposphere, with considerations given to CH4-CO-NO(x)-O3-H(x)O(y) system. It was determined that aqueous phase OH radicals can produce and destroy formic acid droplets in daylight conditions, as well as control formic acid levels in rainwater. It is sugested that the same types of reactions may be involved in the control of acetic acid and other organic acids.

Continuous preparation of ethanol

Abstract: Ethanol is prepared by hydrogenating acetic acid under superatmospheric pressure and at elevated temperatures by a process wherein a predominantly cobalt-containing catalyst is used and acetic acid and hydrogen are passed through the reactor, at from 210° to 330° C. and under from 10 to 350 bar, under conditions such that a liquid phase in not formed during this procedure.

Process for the production of ethanol

Abstract: Ethanol is produced by carbonylation of methanol by reaction with carbon monoxide in the presence of a carbonylation catalyst to form acetic acid which is then converted to an acetate ester followed by hydrogenolysis of the acetate ester formed to give ethanol or a mixture of ethanol and another alcohol which can be separated by distillation Preferably the other alcohol or part of the ethanol recovered from the hydrogenolysis step is recycled for further esterification Carbonylation can be effected using a CO/H2 mixture and hydrogenolysis can similarly be conducted in the presence of carbon monoxide, leading to the possibility of circulating gas between the carbonylation and hydrogenolysis zones with synthesis gas, preferably a 2:1 H2:CO molar mixture being used as make up gas

Production of ethanol from acetic acid

Abstract: Ethanol is produced from acetic acid by esterifying the acetic acid with an olefin having at least 4 carbon atoms, hydrogenating the ester obtained into ethanol and a higher alcohol having at least 4 carbon atoms, removing the ethanol, dehydrating the higher alcohol back to the original olefin and recycling the olefin to esterify the acetic acid.

Curing epoxy resins with anhydrides. Model reactions and reaction mechanism

Abstract: The mechanism of acid curing of epoxy resins catalyzed with tertiary amines was investigated by using model systems composed of phenylglycidyl ether and benzoic acid or acetic acid anhydrides in the presence of benzyldimethylamine. The reaction was studied by NMR spectrometry, liquid chromatography, and ozone absorption. The main findings are that (1) the tert-amine is bound chemically and irreversibly during the reaction under the formation of a quaternary ammonium salt and (2) 1-phenyloxypropanediol-2,3-dibenzoate or diacetate is the main reaction product. The suggested reaction mechanism involves initiation in which the tertiary amine reacts with the epoxy group, giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion; the latter immediately reacts with the anhydride and quaternary salt is formed. In a later stage the carboxy anion of the quaternary salt reacts first with the epoxy group, then with the anhydride. By this reaction diester is formed and the carboxy anion is regenerated.

A quantitative comparison of the extraction of protein fractions from wheat grain by different solvents, and of the polypeptide and amino acid composition of the alcohol-soluble proteins.

Abstract: Using several cultivars, whole milled wheat grain was first extracted with 0.5M NaCl to remove non-protein N, albumins and globulins: the amount of protein subsequently extractable by either 70% ethanol, 55% propan-2-ol, or 50% propan-1-ol (with or without the addition of acetic acid), was then compared. All solvents were tested at 4, 20 and 60°C both with and without the addition of 2-mercaptoethanol (2-ME) as a reducing agent. Raising the temperature, including a reducing agent, and repeated extractions, all combined to maximise protein extractability; least was extracted by 70% ethanol at 4°C and most by 50% propan-1-ol containing acetic acid and 2-ME at 60°C. The differing polypeptide compositions of these alcohol-soluble fractions illustrated why N solubility alone is not a sufficient guide to protein extraction, e.g. 35% of grain N was extractable by either 70% ethanol at 60°C or 70% ethanol containing 2-ME at 4°C, but high mol. wt polypeptides (>60000) were found only in the 60°C extract. In contrast, the complete range of alcohol-soluble polypeptides was extracted by all solvent mixtures based on propan-1-ol, even at 4°C. Amino acid analyses of these alcohol-soluble fractions confirmed the low levels of lysine in fractions free from high mol. wt polypeptides. More glycine was found in all fractions containing high mol. wt polypeptides, but only those extracted by propan-1-ol mixtures had an increased lysine content, the amount of which increased linearly as the extraction temperature was raised. Defatting the milled grain did not affect the extractability of alcohol-soluble proteins, but the amount of protein soluble in 0.5M NaCl decreased. The protein rendered NaCl-insoluble was not extracted by any of the alcoholic solvents tested, hence the N content of the residual material was increased. The inclusion of this denatured metabolic fraction in the residue will affect its amino composition. The problems arising from the retention of the classical nomenclature for Osborne-type fractions are discussed.

Effects of acetic and butyric acids on solvents production by Clostridium acetobutylicum

Abstract: The fermentation of glucose by Clostridium acetobutylicum on a synthetic medium is carried out with a conversion of carbon source into solvents of 32 %. The ratio of butanol, acetone and ethanol products is approximately 0.6 - 1.9 - 6. The synthetic medium supplemented with acetic acid at a concentration of 2 g/l increases acetone formation and the ratio of products is approximately 0.5 - 3 - 6 with a conversion of glucose into solvents of 34 %. The addition of 2 g/l butyric acid permits obtaining a distribution of 0.8 - 2.4 - 6, with a conversion of 35 %.

A new procedure for the oxidation of saturated hydrocarbons

Abstract: The oxidation of adamantane can be achieved with unusual efficiency using molecular oxygen and a system comprising hydrogen sulphide and iron powder in pyridine containing acetic acid and a little water.

Factors influencing product distribution in photocatalytic decomposition of aqueous acetic acid on platinized TiO2

Abstract: The Journal of Physical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Factors influencing product distribution in photocatalytic decomposition of aqueous acetic acid on platinized titania Hiroshi Yoneyama, Yoshiyuki Takao, Hideo Tamura, and Allen J. Bard J. Phys. Chem., 1983, 87 (8), 1417-1422• DOI: 10.1021/j100231a027 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 12, 2009

Synergistic Antimicrobial Effect of Ethanol, Sodium Chloride, Acetic Acid and Essential Oil Components

Abstract: Ethanol, NaCl, acetic acid and essential oil components were examined for their synergistic antimicrobial effects, using air-borne microorganisms and pure cultures of fungi. Antimicrobial assays were carried out at 27°C, using 2% glucose Sabouraud agar. In order to completely suppress the growth of all the contaminating air microorganisms for over 20 days, more than 8% (by volume) ethanol, 25% (wt/vol) NaCl, or 0.2% (by volume) acetic acid was required in the medium. All essential oil components examined, at a concentration of 1 or 2mM, were only moderate or very weak in antimicrobial effect. However, when these substances were applied in pairs, in threes and in fours, they exhibited a potent antimicrobial effect at relatively or considerably lower concentrations.The combination of 3% ethanol, 0.05% acetic acid and 1 m.M perillaldehyde, and the combination of as low as 0.5% ethanol, 2% NaCl, 0.05% acetic acid and 0.5 mM perillaldehyde were sufficient to suppress completely the growth of all contaminating ...

Determination of the hydrothermal degradation products of D-(U-14C) glucose and D-(U-14C) fructose by TLC

Abstract: The hydrothermal degradation was examined using D-(U-14C) glucose and D-(U-14C) fructose. By thin layer chromatography with methylene chloride, tetrahydrofuran (THF), acetic acid −60∶20∶20 as a mobile phase it was, possible to separate and identify the carbohydrates and their reaction products, glyceraldehyde, dihydroxyacetone, methylglyoxal, glycolaldehyde, 5-hydroxymethylfurfural and furfural. Up to 99% of the initial activity was determined by scintillation counting of the TL-chromatograms. A reaction scheme for the hydrothermal degradation of glucose and fructose was obtained from these results.

Oxidation of alkylbenzenes by S2O82−-CuII in acetic acid and acetonitrile

Abstract: L'oxydation des toluenes par le systeme cite dans le titre donne des acetates de benzyle et des benzaldehydes via la formation d'un radical cationique du type benzeniumyle

Photoreduction of polymolybdates(VI) in aqueous solutions containing acetic acid

Abstract: Polymolybdates(VI) have been photochemically reduced to Mov in aqueous solutions containing acetic acid. Carbon dioxide, methane, and succinic acid were isolated as decomposition products of the acetic acid but the quantum yield of their formation was ca. 20 times smaller than that of Mov formation. E.s.r, spin-trapping experiments exhibited the presence of spin-adducts of hydroxyl radical as an oxidation product of water. The photoredox reaction of the polymolybdate(VI) with water was a main process. The reaction mechanism discussed is based on the similarity with the photochemistry for an alkylammonium polymolybdate(VI). The photoredox reaction of the polymolybdate(VI) with water or acetic acid proceeds via the photoinduced formation of a charge-transfer complex between the polymolybdate(VI) and acetic acid, which is preceded by the transfer of an acetic acid proton to an oxygen atom at a photoreducible octahedral site in the polymolybdate(VI).

Polarographic Studies of the Ion-pair Formation and Conjugation Reactions of Acetate and Benzoate Ions in Acetonitrile

Abstract: An acetate ion (A−) formed a homoconjugated species, A− (HA)2, with 2 molecules of acetic acid (HA) in the presence of a large excess of HA in an acetonitrile solution. In the presence of both acetic acid and LiClO4, one molecule of HA was derived from A− (HA)2 by means of a lithium ion to from an ion-paired species, HA2−Li, as follows: A−(HA)2+Li+\oversetKex\ightleftharpoonsHA2−Li++HA. The equilibrium constant, Kex, was evaluated as 1.1×104 from the shift in the anodic half-wave potential of the acetate ion. As for the benzoate ion (A′−) and HA′, similar reactions occured, and the constant of the exchange reaction was evaluated as 6×103. The effect of the sodium ion and HA (or HA′) on the A− (or A′−) ion was complicated. On the other hand, the presence of [M(A′)2]− (M=Li, Na, K) was proved by the shift of the cathodic wave of the alkali metal.The addition of water caused the apparent stability constant of [Li(A′)2]− to decrease extremely.

Dimerisierung einiger organischer Säuren in der Gasphase

Abstract: Experimental results for the compressibility factor of formic acid, acetic acid, and acrylic acid in the low pressure region at temperatures between 45 and 120 °C were used to determine the dimerization constant (2 A ⇌ AA) of these carboxylic acids in the vapour phase. The direct experimental results were evaluated applying three different models for the composition of the gas phase: besides monomers and dimers also the presence of trimers or tetramers was assumed. All three evaluations resulted only in small differences in the entropy and enthalpy of dimerization (maximum differences 6.3 and 5.7 per cent respectively for acetic acid). Assuming the existence of trimers or tetramers resulted in an essentially better agreement between calculated and measured compressibility factors only for formic and acetic acid, but not for acrylic acid. When only the formation of dimers is considered the following dimerization constants were obtained: Formic acid: ln KAA = −18.0763 + 7130.9/(T/K) Acetic acid: ln KAA = −19.1001 + 7928.7/(T/K) Acrylic acid: ln KAA = −22.2774 + 9308.1/(T/K)

Whole-cell bioconversion of vanillin to vanillic acid by Streptomyces viridosporus.

Abstract: A two-step batch fermentation-bioconversion of vanillin (4-hydroxy-3-methoxybenzaldehyde) to vanillic acid (4-hydroxy-3-methoxybenzoic acid) was developed, utilizing whole cells of Streptomyces viridosporus T7A In the first step, cells were grown in a yeast extract-vanillin medium under conditions where cells produced an aromatic aldehyde oxidase In the second step, vanillin was incubated with the active cells and was quantitatively oxidized to vanillic acid which accumulated in the growth medium Vanillic acid was readily recovered from the spent medium by a combination of acid precipitation and ether extraction at greater than or equal to 96% molar yield and upon recrystallization from glacial acetic acid was obtained in greater than or equal to 99% purity

Liquid-chromatographic determination of indole-3-acetic acid and 5-hydroxyindole-3-acetic acid in human plasma.

Abstract: We describe a "high-performance" reversed-phase liquid-chromatographic method for determination of indole-3-acetic acid (I) and 5-hydroxyindole-3-acetic acid (II) in human plasma. I is eluted at 1.0 mL/min with a mixture of 1-pentanesulfonic acid (pH 3.1), methanol, and water. It is detected by fluorometry. A mixture of citric acid/sodium phosphate solution (pH 4.8) and methanol, at 1.5 mL/min, is used to elute II, which is detected with an electrochemical cell. Platelet-poor plasma samples were pretreated with HCl, perchloric acid, and trichloroacetic acid for protein precipitation. Best results were obtained with the last (protein precipitation is incomplete with HCl, while recoveries of I are concentration dependent with perchloric acid). Analytical recoveries were 58% (SD 3.1%, CV 5.3%, n = 12) and 79% (SD 3.3%, CV 5.3%, n = 9) for I and II, respectively. Concentrations of I and II in plasma ranged from 0.61 to 3.32 (mean 1.54, SD 0.59, n = 15) mumol/L and from 33.0 to 102.6 (mean 51.8, SD 20.1, n = 16) nmol/L, respectively.