Showing papers on "Acetone published in 2007"

Novel Acetone Metabolism in a Propane-Utilizing Bacterium, Gordonia sp. Strain TY-5

Abstract: In the propane-utilizing bacterium Gordonia sp. strain TY-5, propane was shown to be oxidized to 2-propanol and then further oxidized to acetone. In this study, the subsequent metabolism of acetone was studied. Acetone-induced proteins were found in extracts of cells induced by acetone, and a gene cluster designated acmAB was cloned on the basis of the N-terminal amino acid sequences of acetone-induced proteins. The acmA and acmB genes encode a Baeyer-Villiger monooxygenase (BVMO) and esterase, respectively. The BVMO encoded by acmA was purified from acetone-induced cells of Gordonia sp. strain TY-5 and characterized. The BVMO exhibited NADPH-dependent oxidation activity for linear ketones (C3 to C10) and cyclic ketones (C4 to C8). Escherichia coli expressing the acmA gene oxidized acetone to methyl acetate, and E. coli expressing the acmB gene hydrolyzed methyl acetate. Northern blot analyses revealed that polycistronic transcription of the acmAB gene cluster was induced by propane, 2-propanol, and acetone. These results indicate that the acmAB gene products play an important role in the metabolism of acetone derived from propane oxidation and clarify the propane metabolism pathway of strain TY-5 (propane → 2-propanol → acetone → methyl acetate → acetic acid + methanol). This paper provides the first evidence for BVMO-dependent acetone metabolism.

Investigations on the structure of dimethyl sulfoxide and acetone in aqueous solution.

Abstract: Aqueous solutions of dimethyl sulfoxide (DMSO) and acetone have been investigated using neutron diffraction augmented with isotopic substitution and empirical potential structure refinement computer simulations. Each solute has been measured at two concentrations—1:20 and 1:2 solute:water mole ratios. At both concentrations for each solute, the tetrahedral hydrogen bonding network of water is largely unperturbed, though the total water molecule coordination number is reduced in the higher 1:2 concentrations. With higher concentrations of acetone, water tends to segregate into clusters, while in higher concentrations of DMSO the present study reconfirms that the structure of the liquid is dominated by DMSO-water interactions. This result may have implications for the highly nonideal behavior observed in the thermodynamic functions for 1:2 DMSO-water solutions.

Density functional investigation of the interaction of acetone with small gold clusters.

Abstract: The structural evolution of Aun (n=2, 3, 5, 7, 9, and 13) clusters and the adsorption of organic molecules such as acetone, acetaldehyde, and diethyl ketone on these clusters are studied using a density functional method. The detailed study of the adsorption of acetone on the Aun clusters reveals two main points. (1) The acetone molecule interacts with one gold atom of the gold clusters via the carbonyl oxygen. (2) This interaction is mediated through back donation mainly from the spd-hybridized orbitals of the interacting gold atom to the oxygen atom of the acetone molecule. In addition, a hydrogen bond is observed between a hydrogen atom of the methyl group and another gold atom (not involved in the bonding with carbonyl oxygen). Interestingly, the authors notice that the geometries of Au9 and Au13 undergo a significant flattening due to the adsorption of an acetone molecule. They have also investigated the role of the alkyl chain attached to the carbonyl group in the adsorption process by analyzing the interaction of Au13 with acetaldehyde and diethyl ketone.

Solubility of Glycine Polymorphs and Recrystallization of β-Glycine

Abstract: The solubilities of α-, β-, and γ-glycine in aqueous solutions containing methanol, ethanol, 2-propanol, or acetone were measured at 310 K. The solubility of all the polymorphs dropped rapidly as a function of the concentration of antisolvent. The solubility of the glycine polymorphs in water−antisolvent mixtures was, in decreasing order: methanol > ethanol > 2-propanol > acetone. The solubility of α-glycine was slightly higher than that of γ-glycine, but the solubility of β-glycine was significantly higher by up to 17 %. The induction time for the recrystallization of β- to α-glycine in those water−antisolvent mixtures was, in decreasing order: methanol > ethanol > acetone > 2-propanol. This signifies that the selection of an antisolvent for preparation of β-glycine can have an important effect on the product.

Direct solid-support sample loading for fast cataluminescence determination of acetone in human plasma.

Abstract: In the current manuscript we describe the development of a novel cataluminescence (CTL) sensor coupled with ionic liquids (ILs)-based headspace solid-phase microextraction (HS-SPME) technologies for the quantification of human plasma acetone levels associated with diabetic disease ex vivo. The unique properties of ILs, such as their nonvolatile and nonflammable nature, coupled with their high thermal stability allow ILs to be conveniently adopted as pseudosolid carriers for direct loading of acetone into a CTL sensor without matrix interference. Acetone from diabetic patient plasma and plasma samples spiked with acetone along with methanol, ethanol, and formaldehyde was conveniently and rapidly extracted and enriched in 3 microL of IL and then rapidly quantified by our CTL sensor. The presence of plasma alone or spiked plasma containing methanol, ethanol, or formaldehyde did not interfere with acetone measurements. HS-SPME-CTL provides higher enrichment efficiency than headspace single-drop microextraction-based CTL (HS-SDME-CTL) methods, possibly due to that the thin film formed in HS-SPME instead of the single IL drop in HS-SDME increases the exchange area for extracted acetone. The enrichment efficiency by HS-SPME-CTL was almost 80-fold higher than that with direct injection using the same volume of aqueous samples and more than 6-fold higher than that using HS-SDME-CTL. Considering that ILs can be easily prepared from inexpensive materials and tuned by the combination of different anions and cations for the extraction of specific analytes from various solvent media, this proposed technology raises an exciting possibility by employing HS-SPME-CTL for the fast determination of specific targets in many fields.

Solubility of stearic acid in various organic solvents and its prediction using non-ideal solution models

Abstract: The solubility of stearic acid in ethanol, methanol, ethyl acetate, and acetone has been measured gravimetrically at various temperatures ranging from 301 to 313 K at atmospheric condition. The solubility of stearic acid in ethyl acetate was found to be the highest, followed by ethanol, acetone and methanol. All experimental data were correlated using non-ideal solution models, namely, the modified Apelblat and the Buchowski equations. The calculated results agreed well with the experimental data.

Interaction of acetone molecules with carbon-nanotube-supported TiO2 nanoparticles : Possible applications as room temperature molecular sensitive coatings

Abstract: Room-temperature detection of acetone by TiO2/multiwall carbon nanotube (MWCNT) sol−gel composites is reported. We found a sizable increase in the resistance during acetone adsorption, the best performance being obtained on sol−gel composites synthesized by the Ti-isopropoxide route and containing functionalized MWCNTs. Sensors based on these composites were highly reproducible, with fast adsorption/desorption cycles at room temperature, and showing a linear response to acetone concentration up to 4000 ppm. In order to better understand our experimental results, some relevant surface reactions have been analyzed in detail by performing both ab initio Hartree−Fock and density functional theory calculations of acetone adsorption on model bare and chemically functionalized (by attaching O, Ti, and OH groups as well as small TixOy clusters) single-wall carbon nanotubes. Interestingly, acetone adsorption on the surface of TiO2/carbon nanotube compounds seems to be mainly dependent on the precise details of the...

Sorption Equilibrium and Thermal Regeneration of Acetone and Toluene Vapors on an Activated Carbon

Abstract: Adsorption and thermal regeneration dynamics of acetone on activated carbon were compared to those of toluene. The adsorption isotherms of acetone on the activated carbon were type-II, but they approached type-III with an increase in temperature. On the other hand, those of toluene were type-I in the experimental range. Although the temperature excursion of toluene was higher than that of acetone in the activated carbon bed, the breakthrough shape of toluene was steeper due to the strong adsorption affinity. Compared to toluene, more concentrated acetone within shorter period of time could be obtained from the activated carbon bed by hot nitrogen purge regeneration because its isotherm approached type-III at high temperature. Therefore, the energy requirement and purge gas consumption for acetone desorption were significantly changed with purge gas velocity, regeneration temperature, and initial bed loading, which was different from toluene. A nonequilibrium and nonadiabatic/nonisothermal model was used t...

Anesthetic properties of the ketone bodies β-hydroxybutyric acid and acetone

Abstract: BACKGROUND:We tested the hypothesis that two metabolites that are elevated in ketosis (β-hydroxybutyric acid, and acetone) modulate ion channels in a manner similar to anesthetics and produce anesthesia in animals.METHODS:α1β2γ2sγ-aminobutyric acid type A (GABAA), α1 glycine, NR1/NR2A N-methyl-d-asp

Solubilities of Betulin in Fourteen Organic Solvents at Different Temperatures

Abstract: The solubilities of betulin in methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, methyl formate, ethyl formate, methyl acetate, ethyl acetate, chloroform, dichloromethane, cyclohexane, and acetone were measured at T = (278.2, 288.2, 298.2, and 308.2) K. The solubilities of betulin in selected organic solvents increase with temperature. A three-parameter equation was used to correlate the experimental data. These data of solubility can be used to guide the processes of crystallization in industry.

One-step methyl isobutyl ketone (MIBK) synthesis from 2-propanol: Catalyst and reaction condition optimization

Abstract: A gas-phase process for methyl isobutyl ketone (MIBK) synthesis from 2-propanol in one-pot is studied as an alternative to the conventional technology for producing MIBK from acetone (DMK). Bifunctional copper/acid–base catalysts able to operate at mild temperatures and atmospheric pressure were prepared and characterized by measuring the acid and base properties as well as the metal dispersion. It was found that a Cu-Mg-Al mixed oxide catalyst gives high MIBK yields. In this catalyst, the metal fraction in loadings of 2–6 wt% promotes the hydro-dehydrogenation steps at high rates whereas the surface acid–base sites of moderate acid and base properties favor the aldol condensation reaction. The effect of different operational conditions such as reaction temperature and reactant partial pressure was also investigated. The MIBK formation rate was enhanced by increasing 2-propanol partial pressure in a wide range, consistently with a positive 2-propanol reaction order in the overall kinetics whereas the presence of hydrogen in the reactant mixture inhibited MIBK synthesis due to a negative order with respect to H 2 . An increase of the reaction temperature and the use of inert atmosphere improved the MIBK yield. By operation at 533 K in N 2 the Cu-Mg-Al catalyst with 6.4 wt% Cu, yields 27% MIBK in comparison to the 30% typically obtained in current commercial liquid-phase high-pressure processes from DMK.

A novel gaseous ester sensor utilizing chemiluminescence on nano-sized SiO2

Abstract: A gaseous sensor for ester vapors has been developed based on their chemiluminescence (CL) on the surface of nano-sized SiO 2 in an airflow. The luminescence characteristics and the optimal conditions for the determination of ethyl acetate by the sensor are investigated. Under the optimized conditions, the linear range of the CL intensity versus the concentration of ethyl acetate vapor is 20–300 ppm with a limit of detection of 3.0 ppm (3 σ ) and a relative standard deviation (R.S.D.) of 1.80% for eight times determination of 300 ppm ethyl acetate. There is no response or weak response when foreign substances including ethanol, methanol, hexane, cyclohexane, benzene and toluene pass through the sensor. However, acetone shows a little response which interferes slightly in the measurement of ethyl acetate. The sensor exhibits good stability and durability after 100 h reaction with 300 ppm ethyl acetate. The possible mechanism of CL from the oxidation of ethyl acetate on SiO 2 is discussed based on the CL spectra and the GC–MS chromatogram of reaction products.

Ruthenium–Lewis Acid Catalyzed Asymmetric Diels–Alder Reactions between Dienes and α,β‐Unsaturated Ketones

Abstract: The complex [Ru(Cp)(R,R-BIPHOP-F)(acetone)][SbF(6)], (R,R)-1 a, was used as catalyst for asymmetric Diels-Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3-dimethylbutadiene) and alpha,beta-unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, alpha-bromovinyl methyl ketone and alpha-chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50-90 % and with enantioselectivities up to 96 % ee. Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90 % ee. alpha-Chlorovinyl methyl ketone performed better than alpha-bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95 % ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)((S,S)-BIPHOP-F)(mvk)][SbF(6)], (S,S)-1 b, and [Ru(Cp)((R,R)-Me(4)BIPHOP-F)(acrolein)][SbF(6)], (R,R)-2 b, provided the basis for a rationalization of the asymmetric induction.

Photochemistry of the Indoor Air Pollutant Acetone on Degussa P25 TiO2 Studied by Chemical Ionization Mass Spectrometry

Abstract: We have used chemical ionization mass spectrometry (CIMS) to study the adsorption and photochemistry of several oxygenated organic species adsorbed to Degussa P25 TiO2, an inexpensive catalyst that can be used to mineralize volatile organic compounds. The molecules examined in this work include the common indoor air pollutant acetone and several of its homologs and possible oxidation and condensation products that may be formed during the adsorption and/or photocatalytic degradation of acetone on titanium dioxide catalysts. We report nonreactive uptake coefficients for acetone, formic acid, acetic acid, mesityl oxide, and diacetone alcohol, and results from photochemical studies that quantify, on a per-molecule basis, the room-temperature photocatalytic conversion of the species under investigation to CO2 and related oxidation products. The data presented here imply that catalytic surfaces that enhance formate and acetate production from acetone precursors will facilitate the photocatalytic remediation of acetone in indoor environments, even at room temperature.

Extraction of ginger rhizome: kinetic studies with dichloromethane, ethanol, 2‐propanol and an acetone—water mixture

Abstract: Summary The kinetics of extraction of [6]-gingerol from ground Jamaican ginger rhizome have been determined at 30°C in dichloromethane, ethanol, isopropanol and an 80% (v/v) acetone + 20% (v/v) water mixture. The extractions all proceeded in three stages: an initial ‘washing’ stage, a fast stage and a subsequent much slower stage. The rate of extraction of hexahydrocurcumin in ethanol was found to follow a simpler pattern. From the first order plots, the diffusion coefficients of the extracted solubles within the ginger particles were calculated. They varied inversely with the 0.6 power of the solvent viscosity, which explained why the rates of [6]-gingerol extraction decreased in the sequence: acetone < acetone + water < dichloromethane < ethanol < isopropanol. These results show that solvents of low viscosity should be chosen to attain fast extraction rates. The diffusion coefficient of [6]-gingerol was also measured at 30°C in pure acetone, ethanol and isopropanol. The values in these bulk solvents were 13–20 times greater than the diffusion coefficients of [6]-gingerol within the ginger particles for the fast stage and over 900–1800 times greater than those for the slow stage. These hindrance factors quantify the effect of the ginger matrix environment on internal diffusion.

Infrared spectroscopy of acetone-hexane liquid mixtures.

Abstract: Acetone and hexane mixtures covering the whole solubility range were studied by Fourier transform infrared attenuated total reflectance spectroscopy. Factor analysis separates the spectra into four principal factor spectra and multiplying factors. Those containing negative factors are abstract, but the spectra are real. A statistical distribution model of the molecules in the solutions rendered the factors real. From these we define the intermediate species that occur in a 1:2 molar ratio of acetone in hexane, present principally in the low acetone concentration regions, and in a 2:1 molar ratio of acetone in hexane, present principally in the higher acetone concentration region. However, except at the concentration range limits where only pure acetone and pure hexane are present, the four species are present over the whole solubility range. The IR spectra of the species indicated very little displacement of the CH stretch bands, HCH deformation bands, and CC stretch bands, although there are some small intensity variations. Most of the modifications are observed on the acetone C=O stretch band. From the gas phase position, a strong bathochromic shift of 19 cm(-1) of the pure liquid is assigned to dipole-dipole interactions. In the 2:1 groupings, the shift that decreases to 15 cm(-1) is due to the diminished dipole-dipole interactions. In the 1:2 groupings, no dipole-dipole interaction can exist, and the bathochromic displacement of 9 cm(-1) is attributed to van der Waals interactions. In the one acetone to two hexanes grouping, no dipole-dipole interaction can exist, and the bathochromic displacement of 9 cm(-1) is attributed to van der Waals interactions. From the statistical distribution of the molecules, we determine that mixtures of hexane and acetone form a random organization with no preferred association or complex.

Experimental Investigation of the Solubility of CO2 in (Acetone + Water)

Abstract: New experimental results are presented for the solubility of carbon dioxide in pure liquid acetone {= 2-propanone, (CH3)2CO} and in solvent mixtures of (acetone + water) at gas-free solvent mixture acetone mole fractions of about (0.05, 0.1, 0.25, 0.5, 0.75, 0.9, and 0.95), temperatures of (313.75, 354.35, and 395.0) K, and total pressures up to about 10 MPa. Numerical values are reported for the (molality scale based) Henry's constant of CO2 in acetone and in (acetone + water) at vanishing amount of the gas in the liquid mixture resulting from the new experimental data by applying the well-known extrapolation procedure. The experimental work is to provide a database for developing and testing thermodynamic models to describe the gas solubility in salt-free and salt-containing mixed solvents as well as to test screening methods based, for example, on molecular simulation.

Single-Phase Titania Nanocrystallites and Nanofibers from Titanium Tetrachloride in Acetone and Other Ketones

Abstract: Single-phase titania nanomaterials were prepared by autoclaving titanium tetrachloride in acetone at 80−140 °C. Depending on the molar ratio of TiCl4 to acetone (TiCl4/Ac), TiO2 materials with different phases and morphologies were obtained. When the TiCl4 concentration was no higher than TiCl4/Ac = 1/15, single-phase anatase TiO2 nanocrystals in sizes ranging from 4 to 10 nm were prepared by tuning TiCl4/Ac ratios from 1/90 to 1/15. However, when the TiCl4 concentration was high enough (e.g., TiCl4/Ac ≥ 1/10), single-phase rutile TiO2 nanofibers were obtained selectively. The materials were characterized comprehensively using X-ray diffraction, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and nitrogen adsorption measurements. With the aid of GC/MS analysis of organic products in the liquid phase, it is shown that the controlled hydrolysis of TiCl4 with water, which was in situ generated from the TiCl4-catalyzed aldol condensation reactions of acetones, played an impor...

Solubility of Cyclotrimethylenetrinitramine (RDX) in Binary Solvent Mixtures

Abstract: Experimental solubilities of cyclotrimethylenetrinitramine (RDX) in binary solvent mixtures, such as γ-butyrolactone + water, cyclohexanone + water, N-methyl pyrrolidone + water, and acetone + water, were measured over the temperature range of 273.15 K to 363.15 K. The enthalpy of dissolution was determined experimentally from the solubility data.

Atmospheric oxidation pathways of propane and its by‐products: Acetone, acetaldehyde, and propionaldehyde

Abstract: [i] Propane (C 3 H 8 ) is one of the most abundant nonmethane hydrocarbons in the atmosphere. It is a fuel widely used, derived from petroleum products during oil and natural gas processing. It can be oxidized in the atmosphere via its reactions with hydroxyl (OH) radicals and chlorine (Cl) atoms and serves as an indicator for the presence of such oxidants. During the atmospheric degradation of propane, various carbonyl compounds are formed, with acetone, acetaldehyde, and propionaldehyde among the most prominent. Carbonyl compounds are relevant because of their toxicity and ability to produce free radicals by photolysis that give rise to stable products, thus providing valuable information about atmospheric oxidation processes. The exact mechanisms of the oxidation pathways of propane have not been properly characterized, although several speculations have been made that determine the oxidation products. The present study investigates the oxidation mechanism of propane, acetone, acetaldehyde, and propionaldehyde by ab inito molecular orbital methods. Detailed pathways leading to experimentally observed products are presented. Equilibrium geometries and energetics, as well as vibrational frequencies of species, transition states, and prereactive complexes are determined at the QCISD(T)/6-311G(2df,2p)//MP2(full)/6-31G(d).