Showing papers on "Acetic acid published in 1992"

Acetic acid formation in escherichia coli fermentation

Abstract: Acetic acid formation in Escherichia coli fermentation has been studied in continuous cultures. Experimental results suggest that the limited capacity of the oxidative metabolism (perhaps the limited capacity of TCA cycle) may be responsible for acetic acid formation. At low growth rates, both anabolic and catabolic requirements may be satisfied by the oxidative metabolism. However, at high growth rates these two demands may exceed the capacity of the oxidative metabolism alone. It is proposed that under these circumstances, E. coli reorganizes the oxidative metabolism to first meet the anabolic requisition and then supply the necessary amount of energy using both the remaining capacity of the oxidative metabolism and acetic acid formation metabolism. Escherichia coli selects acetic acid synthesis as the aerobic energy source because it generates the second largest amount of ATP and NADH(2). According to our proposition, acetic acid formation could be reduced by decreasing the anabolic requirement, i.e., reducing glucose uptake, or by increasing the capacity of the oxidative metabolism. These two approaches were experimentally confirmed by observing reduced acetic acid formation by reducing the glucose uptake with a yeast extract addition and enhancing the capacity of oxidative metabolism with a methionine addition.

Ethanol production from eucalyptus wood hemicellulose hydrolysate by Pichia stipitis.

Abstract: Ethanol production was evaluated from eucalyptus wood hemicellulose acid hydrolysate using Pichia stipitis NRRL Y-7124. An initial lag phase characterized by flocculation and viability loss of the yeast inoculated was observed. Subsequently, cell regrowth occurred with sequential consumption of sugars and production of ethanol. Polyol formation was detected. Acetic acid present in the hydrolysate was an important inhibitor of the fermentation, reducing the rate and the yield. Its toxic effect was due essentially to its undissociated form. The fermentation was more effective at an oxygen transfer rate between 1.2 and 2.4 mmol/L h and an initial pH of 6.5. The hydrolysate used in the experiences had the following composition (expressed in grams per liter): xylose 30, arabinose 2.8, glucose 1.5, galactose 3.7, mannose 1.0, cellobiose 0.5, acetic acid 10, glucuronic acid 1.5, and galacturonic acid 1.0. The best values obtained were maximum ethanol concentration 12.6 g/L, fermentation time 75 h, fermentable sugar consumption 99% ethanol yield 0.35 g/g sugars consumed, and volumetric ethanol productivity 4 g/L day. (

Kinetic studies of epoxidation and oxirane cleavage of palm olein methyl esters

Abstract: The kinetics for the epoxidation of methyl esters of palm olein (MEPOL) by peroxyformic acid and peroxyacetic acid generatedin situ were studied. The rate-determining step was found to be the formation of peroxy acid. Epoxidized MEPOL (EpMEPOL), with almost complete conversion of the unsaturated carbon and negligible ring-opening, can be synthesized by thein situ technique described. The kinetics of the oxirane cleavage of EpMEPOL by acetic acid were studied at various temperatures. The reaction was found to be first-order with respect to the epoxy concentration and second-order to the acetic acid concentration. The activation energy and the entropy of activation for the epoxidation of MEPOL were comparable to those for the oxirane cleavage of EpMEPOL by acetic acid, suggesting that the two reactions are competitive. The success of the epoxidation of MEPOL with only negligible oxirane cleavage is attributed to the heterogeneous nature of the system employed in thein situ technique.

Higher alcohol and acetic acid production by apiculate wine yeasts

Abstract: P. ROMANO, G. SUZZI, G. COMI AND R. ZIRONI. 1992. Ninety-six strains of apiculate wine yeasts were investigated for their ability to produce higher alcohols and acetic acid in synthetic medium. Less isoamyl alcohol and more n-propanol and isobutanol were formed by Hanseniaspora guilliermondii than by Kloeckera apiculata. The latter produced twice as much acetic acid as H. guilliermondii. The production of higher alcohols and acetic acid was found to be a characteristic of individual strains and was statistically significant. In a multivariate analysis of higher alcohol production two main groupings were formed at 86%S, corresponding to the taxa H. guilliermondii and K. apiculata. Strains that produced low amounts (50 mg/1) of acetic acid, comparable with that of Saccharomyces cerevisiae, were found in both species of apiculate yeasts.

Isolation and characterization of acetic acid-tolerant galactose-fermenting strains of Saccharomyces cerevisiae from a spent sulfite liquor fermentation plant.

Abstract: From a continuous spent sulfite liquor fermentation plant, two species of yeast were isolated, Saccharomyces cerevisiae and Pichia membranaefaciens. One of the isolates of S. cerevisiae, no. 3, was heavily flocculating and produced a higher ethanol yield from spent sulfite liquor than did commercial baker's yeast. The greatest difference between isolate 3 and baker's yeast was that of galactose fermentation, even when galactose utilization was induced, i.e., when they were grown in the presence of galactose, prior to fermentation. Without acetic acid present, both baker's yeast and isolate 3 fermented glucose and galactose sequentially. Galactose fermentation with baker's yeast was strongly inhibited by acetic acid at pH values below 6. Isolate 3 fermented galactose, glucose, and mannose without catabolite repression in the presence of acetic acid, even at pH 4.5. The xylose reductase (EC 1.1.1.21) and xylitol dehydrogenase (EC 1.1.1.9) activities were determined in some of the isolates as well as in two strains of S. cerevisiae (ATCC 24860 and baker's yeast) and Pichia stipitis CBS 6054. The S. cerevisiae strains manifested xylose reductase activity that was 2 orders of magnitude less than the corresponding P. stipitis value of 890 nmol/min/mg of protein. The xylose dehydrogenase activity was 1 order of magnitude less than the corresponding activity of P. stipitis (330 nmol/min/mg of protein).

Catalysts and processes for the manufacture of vinyl acetate

Abstract: A shell impregnated catalyst for use in the production of vinyl acetate from ethylene, acetic acid and an oxygen containing gas is provided. The catalyst has a productivity of greater than 661 grams of vinyl acetate per hour per liter of catalyst at 150° C. and consists essentially of: (1) a catalyst support having a particle diameter from about 3 to about 7 mm and a pore volume of 0.2 to 1.5 ml per gram (2) palladium and gold distributed in the outermost 1.0 mm thick layer of the catalyst support particles, and (3) from about 3.5 to 9.5% by weight of potassium acetate. The catalyst is characterized by having a gold to palladium weight ratio in the range 0.60 to 1.25.

Dependence on the Preparation Procedure of the Polymorphism and Crystallinity of Chitosan Membranes

Abstract: Differences in the polymorphism and crystallinity of chitosan were found in membranes prepared by different procedures when examined by X-ray diffraction measurements for four samples of chitosan differing in the degree of polymerization. When an acetic acid solution of chitosan was dried in air and then soaked in an alkaline solution (method A), both hydrated and anhydrous polymorphs of chitosan were present in the resulting membranes; the latter polymorph made chitosan insoluble in common solvents of chitosan, and its crystallinity increased with decreasing chitosan molecular weight. When a highly concentrated chitosan solution in aqueous acetic acid was neutralized with an alkaline solution (method B), no anhydrous polymorphs were detected in the membrane because of incomplete drying. When aqueous formic acid was used as the solvent, behavior basically similar to that in aqueous acetic acid was observed. In contrast, even with method A, aqueous hydrochloric acid gave a chitosan membrane having very little anhydrous crystallinity. The crystalline polymorph called "1-2", which has been proposed to be one of four chitosan polymorphs, is considered to be a mixture of hydrated and anhydrous crystals.

Quantitative studies on furfural and organic acid formation during hydrothermal, acidic and alkaline degradation of D -xylose

Abstract: Chromatographic analysis of the degradation ofD-xylose either in plain water or aqueous sulfuric acid at temperatures ranging from 180 – 220°C gave up to 50 mol% of furfural. Activation energies did not differ significantly between reactions in plain water (E a =119.4 kJ/mol), 0.001M H2SO4 (E a =120.6 kJ/mol), 0.01M H2SO4 (E a =130.8 kJ/mol), and 0.1M H2SO4 (E a =120.7 kJ/mol). However, under alkaline conditions the activation energy was only 63.7 kJ/mol, indicating a different reaction mechanism. Isotachophoretic analyses revealed the formation of pyruvic, formic, glycolic, lactic, and acetic acid. While the relative yields of these acids ranged from 0.8 to 7% under hydrothermal and acidic conditions, 10 – 23% were obtained in alkaline degradation.

Acetic Acid Action on Beef Tissue Surfaces Contaminated with Salmonella typhimurium

Abstract: Beef tissue surfaces (lean and fat) were artificially contaminated with Salmonella typhimurium and then sanitized with 2% acetic acid. The reduction in bacterial population by the acid treatment was consistently proportional to the initial inoculum level for both tissue types. Increasing the amount of organic material in the inoculating menstra reduced the bactericidal effects of acetic acid on Salmonella typhimurium on fat tissue, although there was no change in effectiveness on lean tissue. Acid treatment sublethally injured about 65% of the population on both lean and fat tissue, and the residual effects of the acid resulted in a 1 log cycle reduction in bacterial population on fat tissue over 4 hr.

Acetic Acid and its Derivatives

Abstract: Part 1 Chemistry and methods for the manufacture of acetic acid: bioderived acetic acid, Lee R. Partin and William H. Heise ethylene- and acetylene-based processes, A. Thomas Fanning manufacture via hydrocarbon oxidation, Gether Irick manufacture via methanol carbonylation, Joseph R. Zoeller other synthesis gas-based acetic acid processes, Bruce L. Gustafson and Joseph R. Zoeller production economics, Peter N. Lodal. Part 2 Thermophysical properties of acetic acid and its aqueous solutions: acetic acid, William H. Seaton aqueous solutions, William H. Seaton. Part 3 Selected acetic acid derivatives: acetic anhydride, Steven L. Cook ketene, Peter W. Raynolds diketene and acetoacetates, Robert J. Clemens and J. Stewart Witzeman vinyl acetate, Charles E. Sumner and Joseph R. Zoeller cellulose acetate, Lanny C. Treece and Griffin I. Johnson alcohol acetates J. Stewart Witzeman and Victor H. Agreda halogenated derivatives, Paul R. Worsham nitrogen derivatives, Frank Cooke specialty chemicals, Philip C. Heidt and Ryan C. Schad chain growth - acrylics and other carboxylic acids, J. Adrian Hawkins and Joseph R. Zoeller key properties and hazards, Peter N. Lodal.

A Novel Extractive Fermentation Process for Propionic Acid Production from Whey Lactose

Abstract: An extractive fermentation process was developed to produce propionate from lactose. The bacterium Propionibacterium acidipropionici was immobilized in a spiral wound, fibrous matrix packed in the reactor. Propionic acid is the major product from lactose fermentation, with acetic acid and carbon dioxide as byproducts. Propionic acid is a strong inhibitor to this fermentation. A tertiary amine was used to selectively extract propionic acid from the bioreactor, hence enhancing reactor productivity by over 100 %. We also speculate that by selectively extracting propionic acid, lactose metabolism can be directed to yield more propionate and less byproducts. Other advantages of extractive fermentation include better pH control (by removing acid products) and a purer product. The propionic acid present in the extractant can be easily stripped with small amounts of an alkaline solution, resulting in a concentrated propionate salt. The extractant was also regenerated in this stripping step. Thus, the process is energy-efficient and economically attractive.

Process for the production of terephthalic acid

Abstract: A terephthalic acid slurry in acetic acid is produced by oxidising p-xylene in acetic acid, removing water by evaporation of a stream of water and acetic acid, and returning acetic acid to the oxidation step. The terephthalic acid is separated from the reaction medium in a first zone to leave a deposit on a band, the deposit is washed with a first aqueous medium in a second zone, removed from the band in a third zone, and admixed with a second aqueous medium. Reaction medium is passed from the first zone to the oxidation step and terephthalic acid is recovered, preferably after further purification.

Acidic Alkali Metal Salts and Ammonium Salts of Keggin-type Heteropolyacids as Efficient Solid Acid Catalysts for Liquid-phase Friedel-Crafts Reactions

Abstract: Acidic salts of the Keggin-type heteropolytungstic acids prepared through partial neutralization with alkali metal carbonates or ammonium hydroxide had relatively large surface areas, and showed high catalytic efficiency as insoluble solid acid catalysts in Friedel-Crafts alkylation and acylation using benzyl chloride, benzoyl chloride, benzoic anhydride, benzoic acid, acetic anhydride, and acetic acid as electrophiles.

Process for producing ethyl acetate

Abstract: Ethyl acetate is produced in good yield by reacting ethylene with acetic acid in the presence of a catalyst comprising a tungstophosphoric acid of which 10-90% of the total amount of proton is replaced with a member selected from the group consisting of (a) cesium metal cation, (b) a combination of cesium metal cation and at least one cation selected from alkali metal cations other than cesium cation, and (c) a combination of cesium metal cation and at least one cation of iron group metal cations.

Catalytic Properties Of Promoted Vanadium Oxide In The Oxidation Of Ethane In Acetic Acid

Abstract: ReO3-like oxides belonging to various systems such as : [V-O], [V-P-O] and [Mo-V-Nb], have been prepared, characterized and studied in the mild oxidation catalysis of ethane, Pure and Pd doped (VO)2P2O7 are found to be very selective catalysts for the direct oxidation of ethane in acetic acid and anhydride as low as 250°C, whereas oxides having the composition [Mo0.73V0.18Nb0.09] catalyze selectively either the oxidative dehydrogenation of ethane in ethylene near 350°C, or its oxidation to acetic acid at lower temperatures, according to the mode of preparation.

Transition Metal Catalyzed Acetic Acid Synthesis from Methane and CO

Abstract: Methane reacts with CO to give acetic acid in good yield by the CuSO4 and/or Pd(OCOEt)2 catalysts via C-H bond activation. This reaction has an advantage over the method which uses methanol and rhodium catalysts, in that cheap methane and copper catalysts can be used. Propane also reacts with CO to give butyric acids.

Propionic acid fermentation by Propionibacterium acidipropionici: effect of growth substrate

Abstract: Batch propionic acid fermentations by Propionibacterium acidipropionici with lactose, glucose, and lactate as the carbon source were studied. In addition to propionic acid, acetic acid, succinic acid and CO2 were also formed from lactose or glucose. However, succinic acid was not produced in a significant amount when lactate was the growth substrate. Compared to fermentations with lactose or glucose at the same pH, lactate gave a higher propionic acid yield, lower cell yield, and lower specific growth rate. The specific fermentation or propionic acid production rate from lactate was, however, higher than that from lactose. Since about equimolar acid products would be formed from lactate, the reactor pH remained relatively unchanged throughout the fermentation and would be easier to control when lactate was the growth substrate. Therefore, lactate would be a preferred substrate over lactose and glucose for propionic acid production using continuous, immobilized cell bioreactors.

Reactivity of malonyl radicals. Synthesis of substituted dihydronaphthalenes by manganese(III) oxidation of diethyl .alpha.-benzylmalonate in the presence of alkynes

Abstract: Oxidation of diethy α-benzylmzalonate (1) by Mn(III) acetate in acetic acid at 70 o C in the presence of alkynes 2a-j leads to dihydronaphalene derivatives 3a-j in moderate to good yields. A homolytic mechanism, involving oxidation of 1 to the corresponding malonyl radical, its addition to a triple bond, and intramolecular homolytic aromatic substitution of the vinyl radical adducts, is suggest. Propargylic hydrogen abstraction and dimerization at the malonic position for less reactive alkynes are the main side reactions observed

Daphniphyllum alkaloids. 15. Total syntheses of (.+-.)-methyl homodaphniphyllate and (.+-.)-daphnilactone A

Abstract: Biomimetic total syntheses of (±)-daphnilactone A (6) and (±)-methyl homodaphnipohyllate (4) have been carried out. The syntheses began with the preparation of tricyclic lactone ether 18d, which was reduced to diol 19d with LiAlH 4 . Oxidation of 19d gave a sensitive dialdehyde (20d), which was treated sequentially with ammonia and warm acetic acid to obtain the hexacyclic amino ether 22d

The final step in the biosynthesis of hydrogenobyrinic acid is catalyzed by the cobH gene product with precorrin-8x as the substrate.

Abstract: The final enzymatic reaction in the conversion of precorrin-6x to hydrogenobyrinic acid by cell-free protein preparations from Pseudomonas denitrificans was shown to be inhibited by hydrogenobyrinic acid Use was made of this property to prepare the last biosynthetic precursor of hydrogenobyrinic acid, named precorrin-8x Double-labeling experiments, mass spectrometry, and UV-visible light spectroscopy studies established that precorrin-8x was at the oxidation level of a corrin and differed from precorrin-6x by two additional methyl groups (presumably at C-5 and C-15) and decarboxylation of the acetic acid side chain at C-12 Precorrin-8x was not a corrin but had the same mass as hydrogenobyrinic acid, thus showing that this latter compound is synthesized from the former by a rearrangement The enzyme catalyzing this rearrangement was purified 80-fold to homogeneity from a recombinant strain of P denitrificans, sequenced at its N terminus, and shown to be encoded by the cobH gene It was identical to the previously described hydrogenobyrinic acid-binding protein (F Blanche, D Thibaut, D Frechet, M Vuilhorgne, J Crouzet, B Cameron, G Muller, K Hlineny, U Traub-Eberhard, and M Zboron, Angew Chem Int Ed Engl 29:884-886, 1990) This enzyme had a Km of 091 +/- 004 microM and a Vmax of 230 nmol h-1 mg-1 at pH 77 and was competitively inhibited by hydrogenobyrinic acid with a Ki of 017 +/- 001 microM It is proposed that the cobH gene product is a mutase which transfers the methyl group from C-11 to C-12 Images

Photoluminescence from zinc oxide powder to probe absorption and reaction of oxygen, carbon monoxide, hydrogen, formic acid, and methanol

Abstract: Photoluminescence was used to probe adsorption and reaction phenomena on a zinc oxide surface of oxygen, hydrogen, carbon monoxide, methanol, formic acid, and acetic acid. At 10{sup -6} Torr evacuation, hydrogen and carbon monoxide adsorption was completely reversible; oxygen, partly so; and methanol, formic acid, and acetic acid were irreversible. Formic acid dissociation and methanol oxidation created intermediates that caused an increase in visible emissions that may be related to the creation of oxygen vacancies. 57 refs., 10 figs.