Showing papers on "Acetone published in 1993"

Alumina-supported silver catalysts for the selective reduction of nitric oxide with propene and oxygen-containing organic compounds

Abstract: The selective catalytic reduction of nitric oxide with propene and oxygen-containing organic compounds over several alumina-supported metal catalysts was investigated. Alumina-supported silver catalysts showed high activities in the presence of water and excess oxygen, while water vapor significantly decreased the activities of alumina and Co/Al2O3 which were highly active in the absence of water. It was also found that oxygen-containing organic compounds such as ethanol and acetone were more effective than propene in reducing nitric oxide over Ag/Al2O3 in the presence of water and excess oxygen.

Production of acetone, butanol and ethanol (ABE) from potato wastes: fermentation with integrated membrane extraction

Abstract: The technical possibilities of the microbial production of acetone, butanol and ethanol (ABE) from potato waste using in-line solvent recovery, are evaluated. Clostridium acetobutylicum DSM 1731 produces up to 20 g·l−1 of solvents when grown on a medium containing 14% (w/v) potato powder. Using a polypropylene perstraction system and a oleyl alcohol/decane mixture as the extractant, the product yield (based on total solvents and potato dry weight) increased from 0.13 g·g−1 to 0.23 g·g−1. The recovery system worked well for 50 h, after which membrane fouling frustrated proper operation. In the second system a microfiltration step was incorporated whereas the solvents were extracted through a hydrophilic membrane using fatty acid methyl esters from sunflower oil as an extractant. This process configuration resulted in a comparable increase of ABE production.

Vanillin-HCl method for condensed tannins: Effect of organic solvents used for extraction of tannins

Abstract: Tannins are generally extracted using aqueous organic solvents, mainly methanol and acetone. The presence of various concentrations of methanol in the sample containing catechin or tannins did not alter the kinetics of their reaction, but the absorbance depended on the amount of methanol in the sample; the higher the methanol, the higher was the absorbance. Acetone reacted with acidified vanillin to produce a chromogen with λmax at 548 nm, which produce a substantial error in the determination of condensed tannins. In the presence of acetone, the time courses of the reaction for catechin and tannins were different, which depended on the acetone concentration and the reaction temperature. Reaction conditions for catechin and tannins that enable their measurement in the presence of acetone are presented.

Vibrational spectrum of the acetone-water complex: a matrix isolation FTIR and theoretical study

Abstract: The FT-infrared absorption spectrum of the hydrogen-bonded acetone-water complex has been investigated in solid argon matrices. Acetone and water vapors were co-condensed with an excess of argon gas at 12 K, giving rise to red- or blue-shifted absorptions near most of those associated with the fundamental transitions of matrix-isolated acetone or water. Vibrational shifts are indicative of a 1:1 complex of acetone and water, in which water is hydrogen-bonded to the carbonyl oxygen of acetone. Accordingly, red shifts are observcd for the C=O stretching mode of acetone and the O-H stretching modes of water. Corresponding shifts of similar magnitude were observed when d 6 -acetone was used

Highly selective one-step formation of methyl isobutyl ketone from acetone with a magnesia supported nickel catalyst

Abstract: A new catalyst for the production of methyl isobutyl ketone (MIBK) from acetone and hydrogen in one step at atmospheric pressure has been prepared. The catalyst was obtained by impregnation of MgO with an aqueous solution of nickel nitrate, dried, calcined in air and reduced in hydrogen. This catalyst showed a high selectivity to MIBK, reaching in some experiments between 60 and 80%. A loss of activity with time on stream, probably due to coke deposition was also found. An increase in reduction temperature from 300 to 500 °C gives a decrease in MIBK selectivity that is due to an increase in the yield of 2-propanol.

Use of partial acetone conversion for capacity increase and quality/yield improvement in the bisphenol-A reaction

Abstract: Product quality productivity of continuous bisphenol-A (BPA) are increased by increasing the flow rate of reactants through the reactor and decreasing % acetone conversion in the presence of an ion exchange resin catalyst and an optional free mercaptan promoter.

Cosolvency effects on copolymer solutions at high pressure

Abstract: Cloud-point data to 180°C and 2800 bar are presented for polyethylene, poly(methyl acrylate), and two poly (ethylene-co-methyl acrylate) copolymers (10 and 31 mol % methyl acrylate) in propane and chlorodifluoromethane with two cosolvents, acetone and ethanol. The addition of small amounts of either cosolvent to the copolymer-solvent mixtures shifts the cloud-point curve to lower pressures and temperatures, as both cosolvents provide favorable polar interactions with the acrylate group in the backbone of the copolymer. Ethanol has a larger effect than acetone since ethanol hydrogen bonds to the acrylate group

Process for the production of bisphenols

Abstract: The invention relates to a process for the production of bisphenols from acetone and phenols in the presence of sulfonic acid ion exchanger resins modified with alkyl-SH groups, in which 0.6 to 5% by weight H2 O is added to the mixture of phenol and acetone before the reaction.

Kinetics of inclusion

Abstract: The kinetics of inclusion of acetone vapour by an organic diol host have been measured as a function of temperature and vapour pressure of acetone.

Controlled-ph batch butanol-acetone fermentation by low acid producing Clostridium acetobutylicum B18

Abstract: C. acetobutylicum B18 produced a large amount of butanol over a wide range of pH (4.5–6.0). At pH 6.0 fermentation and cell growth were most active at pH 6.0, and the highest values of glucose consumption rate (4.37 g/L-h), butanol productivity (1.0 g/L-h), butyric acid recycle rate (0.31 g/L-h), and cell growth rate (0.2 h-1) were obtained. There existed a critical pH between 6.0 and 6.5 above which cells switched to organic acid producing mode. Clostridial stage appeared essential for solvent production by strain B18 but sporulation was not necessary for solvent formation.

Biocatalysis of chlorophyllase from the alga Phaeodactylum tricornutum in a water/miscible-organic-solvent system

Abstract: The hydrolytic activity of a partially purified chlorophyllase obtained from the alga Phaeodactylum tricornutum was determined in different mixtures of acetone and Tris/HCl buffer solution (20 mM, pH 8.0) used as water/miscible-organic-solvent system. The most appropriate concentrations of acetone for chlorophyll-ase activity were 17.5 and 30% respectively at 25 o C and 32.5 o C incubation temperatures. Using the optimized water/acetone ratio, the optimal pH for chlorophyllase activity was found to be 8.0, whereas the time of incubation and the amount of required enzyme were 2 h and 0.30 μg of protein respectively

Nail polish remover with gelatin

Abstract: A nail polish or lacquer removing composition is provided that includes a volatile organic solvent such as acetone, gelatin and glycerin present to stably suspend the gelatin in the solvent.

The Hydrolysis of Bis(2-chloroethyl) Sulfide (Sulfur Mustard) in Aqueous Mixtures of Ethanol, Acetone and Dimethyl Sulfoxide

Abstract: The rate of hydrolysis of bis (2-chloroethyl) sulfide (sulfur mustard) in aqueous mixtures of ethanol, acetone and dimethyl sulfoxide has been measured and compared with previously reported values. Rate constants in water at 25°C for the two consecutive hydrolysis reactions undergone by sulfur mustard were estimated to be (2.93±0.15)×10-3 and (3.87±0.14)×10-3 s-1. Charge separation of 0.42 in the transition states was indicated together with significant solvation of the positive end of the transition state dipoles.

Alumina-supported zinc-cobalt spinel oxide catalyst for combustion of acetone, toluene and styrene

Abstract: A high-dispersity zinc-cobalt spinel oxide is synthesized from a coprecipitated hydroxide-carbonate precursor. A method is proposed for the preparation of a γ-Al 2 O 3 -supported zinc-cobalt oxide catalyst involving the complete oxidation of organic substances so that the penetration of the cobaltite phase inside the granules is avoided. Catalytic tests for the oxidation of acetone, toluene and styrene vapors were performed in a microreactor and in a pilot plant installation and complete combustion of the three substances was achieved at temperatures lower than 350° C. The high thermal stability of zinc cobaltite and the limitations of the interaction between the active phase and the support ensured the stability of the catalyst during the reaction. The temperature at which complete combustion was reached increased in the sequence acetone

Sonochemistry of acetone and acetonitrile in aqueous solutions. A spin trapping study.

Abstract: The 50 kHz sonolysis of argon-saturated water-acetone and water-acetonitrile mixtures was studied by EPR and spin trapping with 3,5-dibromo-4-nitrosobenzenesulfonate over a wide range of solvent composition. For both systems a single maximum was observed for the spin adduct yield of methyl radicals and of the radicals formed by H-abstraction from acetone and acetonitrile. These results combined with previous studies of water-methanol and water-ethanol mixtures indicate that the greater the vapor pressure of the volatile organic component, the lower the concentration of organic solute at which the maximum radical yield occurs. Methyl radicals from acetone are formed by C–C bond scission in the collapsing argon bubbles. For acetonitrile, C–H bond scission at high temperature is followed by H-addition to the triple bond and the decomposition of this intermediate radical to form methyl radicals. Since Anbar has shown (Science 161, 1343, 1961) that sonoluminescence and acoustic cavitation occur during the impa...

Acidity constants of some hydroxy azopyrazolopyridines in mixed aqueous-organic solvents

Abstract: The acid dissociation constants of four hydroxy azo pyrazolopyrimidine derivatives were determined in aqueous−organic solvent mixtures. The organic solvents are methanol, ethanol, acetone, and dimethylformamide. The results obtained are discussed in terms of the solvent characteristics. The ionization constants of the dyes in question depend largely on both the proportion and the nature of the organic cosolvent. Hydrogen-bonding interactions of the conjugate base with solvent molecules as well as the solvent basicity contribute the major effects on the ionization process. The effect of molecular structure of the azo compound on the pKa value is discussed.

Preparation of O-substituted hydroxylammonium salts

Abstract: O-substituted hydroxylammonium salts are prepared by hydrolysis of acetone oxime ethers with acid in the presence of an additive, removing acetone and water by distillation with the aid of the additive.

Process for the production of high-purity bisphenol A

Abstract: The invention relates to a special process for the production of high-purity bisphenol A from acetone and phenol in the presence of acidic catalysts.

Acetone-sensitized photolysis of 5-iodouracil and 5-iodouridine in aqueous solution in the presence of alcohols: free radical chain mechanism

Abstract: The photolysis of 5-iodouracil (IU) and 5-iodouridine (IUd) in deoxygenated aqueous solution was studied as a function of pH and in the presence of alcohols. UV and high performance liquid chromatography (HPLC) analysis shows that uracil and I − are the photoproducts of IU. The quantum yield Φ IU→HU of uracil formation from IU in the presence of 2-propanol (1.4 M), using continuous 254 nm radiation, increases with pH from 0.058 in neutral solution to 0.4 at pH 13. The conversion is significantly enhanced by acetone (0.12 M); for an intensity of I 254 =2.2 mW cm -2 , Φ IU→HU -0.9 and 10 at pH 7 and 12 respectively. Linear dependences of Φ IU→HU vs. I 254 − 1 2 were obtained and, at fixed pH and I 254 , Φ IU→HU values decrease with decreasing concentrations of acetone or 2-propanol. The chain reaction is initiated by hydrogen-atom abstraction by triplet acetone from 2- propanol. The suggested propagation sequence is electron transfer from (CH 3 ) 2 COH/(CH 3 ) 2 CO − radicals to IU, thereby yielding acetone, I − and the uracilyl radical, which regenerates the alcohol radical by hydrogen- atom abstraction from 2-propanol. The increase in Φ IU→HU with increasing pH is mainly ascribed to a higher efficiency of electron transfer from the (CH 3 ) 2 . CO − radical to the IU anion than from the (CH 3 ) 2 . COH radical and to the slower termination reaction of (CH 3 ) 2 . CO − . Similar dependences and comparable Φ values were obtained for IUd. The chain reaction is suppressed by traces of oxygen. An indication for a chain reaction also in the absence of acetone is based on the linear dependence of Φ IU→HU vs. I 254 − 1 2 at pH 13.

Synthesis, isolation, and reactivity of a deuterated mustard simulant: 2-(phenylthio)ethyl-2,2-d2 chloride

Abstract: We have achieved the synthesis and isolation, without substantiel label scrambling, of 2-(phenylthio)-ethyl-2,2-d 2 chloride (2-Cl), a compound useful in modeling reactions of mustard and other highly reactive β-thioethyl chlorides. 2-Cl undergoes slow label scrambling upon dissolution in hot, dry acetonitrile or acetone. Rates of scrambling of the deuterium label in 2-Cl have been measured by following proton NMR changes. Our present work clearly demonstrates that cyclic sulfonium ions are involved in these scrambling reactions. In anhydrous or aqueous acetone, thiourea traps the sulfonium ion intermediate to give stable, label-scrambled thiouronium salts. In anhydrous acetone, in competition with formation of the thiouronium salts, chloride return occurs giving 2-Cl and its label-scrambled isomer, 2-(phenylthio)ethyl-1,1-d 2 chloride (1-Cl). However, no chloride return is observed in 60% aqueous acetone. Mechanistic implications of these results are presented

Production of highly pure bisphenol a

Abstract: PURPOSE:To produce the highly pure bisphenol A from the adduct crystals of bisphenol A to phenol. CONSTITUTION:A method for producing highly pure bisphenol A comprises reacting phenol with acetone in the presence of an acid catalyst, crystallizing the bisphenol A-phenol adduct from the phenol solution of the produced bisphenol A, separating the produced crystals from the solution, and furthermore subjecting the crystals to dissolution, crystallization, and solid-liquid separation operations once to plural times.

Purification of acetone

Abstract: The present invention includes a process for removing aldehydes from acetone having aldehyde impurities comprising contacting the acetone with a sufficient amount of at least one diamine compound to react with at least a portion of the aldehyde and heating the acetone in the presence of the diamine compound sufficiently to result in reaction of the diamine compound and aldehyde, thus reducing the amount of aldehyde in the acetone. It is preferred that the process is an improvement in a process for purifying crude acetone having aldehydes therein, by fractionally distilling the acetone in a multiple plate distillation, the improvement comprising adding to the acetone a sufficient amount of at least one diamine compound to react with at least a portion of the aldehydes.