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Showing papers on "Acetone published in 2001"


Journal ArticleDOI
TL;DR: In this article, a silicalite-silicon composite membrane (306μm thick) was made in a laboratory and characterized for flux and selectivities using model acetone ethanol butanol solution.

240 citations


Journal ArticleDOI
TL;DR: In this paper, a preliminary optical fiber reactor (OFR) that employs bare quartz fibers as a light-transmitting support of TiO2 was tested for gas treatment by investigating photocatalytic oxidation of acetone in air.
Abstract: A preliminary optical fiber reactor (OFR) that employs bare quartz fibers as a light-transmitting support of TiO2 was tested for gas treatment by investigating photocatalytic oxidation of acetone in air (50–750 ppmv). Using one or four TiO2-coated fibers in a continuous flow photoreactor, a steady-state conversion up to 80% was achieved at ambient temperature and pressure. The kinetic behavior of the acetone conversion in this study could be described by zero-order kinetics. The characteristics of coated-optical fibers were quantitatively analyzed and their use in photocatalytic gas treatment was discussed in detail. All the acetone molecules degraded was quantitatively converted to CO2 with no intermediates detected. No noticeable deactivation was observed within a few hours’ operation under the present experimental conditions. The conversion of acetone linearly increased with the incident light intensity without showing any sign of saturation. The transmitted light intensity through a TiO2-coated optical fiber exponentially decreased along the fiber, showing 90% extinction within 30 cm. The photocatalytic conversion measured as a function of the coated-fiber length showed a similar trend. An optimal coating thickness was found at around 1.5m above which the photocatalytic efficiency was reduced. The presence of water vapor reduced the reactivity due to the competitive adsorption on active surface site with acetone. While a measurable conversion of acetone was observed in the absence of O2, increasing O2 concentration up to 15% effectively enhanced the conversion. © 2001 Elsevier Science B.V. All rights reserved.

223 citations


Journal ArticleDOI
03 Jan 2001-Langmuir
TL;DR: In this paper, it was found that the availability of Lewis acid sites is essential for anchoring acetone molecules to the surface, and when intimately coupled, the Lewis acid and base sites generate pair sites of particularly strong adsorption capacity toward condensation products thus formed.
Abstract: Adsorption and surface reactions of acetone vapor were observed on the title oxides at room and higher temperatures (up to 400 °C), using in situ infrared spectroscopy. The results were correlated with results of infrared spectroscopy of adsorbed pyridine, to assess impacts of the surface acid−base properties. It was found that the availability of Lewis acid sites is essential for anchoring acetone molecules to the surface. Coexisting Lewis base sites catalyze condensation of the acetone molecules into mesityl oxide surface species, via formation and subsequent decomposition of enolate and diacetone alcohol species. When intimately coupled, the Lewis acid and base sites generate pair sites of particularly strong adsorption capacity toward condensation products thus formed. Consequently, surface active sites are blocked and adsorptive and catalytic interactions of acetone are largely suppressed.

198 citations


Journal ArticleDOI
TL;DR: The enantioselective aldol reaction using a novel binuclear zinc catalyst of acetone with several aldehydes gave products in good yields with a high level of enantiOSElectivity.

135 citations


Journal ArticleDOI
TL;DR: Sulfonic acid groups anchored to the surface of mesoporous MCM-41 silica have been identified with S K-edge XANES spectra and the material is an efficient catalyst for the liquid phase condensation of phenol with acetone to form Bisphenol-A with high selectivity.

134 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used Proton-transfer-reaction mass spectrometry (PTRS) to measure acetone and other gas phase products from the oxidation of α- and β-pinene initiated by OH radicals in air and in the presence of NO x.

101 citations


Journal ArticleDOI
TL;DR: In situ 13C NMR with both CAVERN and pulse−quench methods was used to understand the chemistry of acetone on the silico-aluminophosphate catalyst HSAPO-34.
Abstract: In situ 13C NMR with both CAVERN and pulse−quench methods was used to understand the chemistry of acetone on the silico-aluminophosphate catalyst HSAPO-34. The isotropic shift of [2-13C]acetone shows that most of the acid sites on this catalyst are weaker than those on aluminosilicate zeolites, but a minority site was resolved with a shift higher than that on zeolite HZSM-5. At elevated temperatures, acetone dimerized to diacetone alcohol and dehydrated to mesityl oxide. Mesityl oxide cracked in the presence of water to acetic acid and isobutylene. Trimerization of butenes formed a significant amount of a persistent carbenium ion with unusual spectroscopic properties, and this is proposed to be the heptamethylcyclopentenyl cation, the first observation of a persistent carbenium ion on a SAPO catalyst. Chemical shift calculations at the GIAO-MP2 level revealed a discrepancy for one signal of the proposed cation but ruled out an alternative assignment. Methylaromatic formation coincided with cyclopentenyl c...

89 citations


Journal ArticleDOI
TL;DR: In situ prepared manganese complexes with ligands 1 -5 have been used in the catalytic oxidation of sulfides to sulfoxides using hydrogen peroxide at 0°C in acetone.

81 citations


Journal ArticleDOI
TL;DR: Pd/Mg(Al)O samples were evaluated in the gas phase reaction of acetone with hydrogen to methyl isobutyl ketone (MIBK) as mentioned in this paper.
Abstract: Pd/Mg(Al)O samples (0.05 < Pd < 0.5 wt%) were evaluated in the gas phase reaction of acetone with hydrogen to methyl isobutyl ketone (MIBK). The catalysts were prepared by impregnating a calcined Mg–Al layered double hydroxide with Pd acetylacetonate in toluene solution. The highest selectivity to MIBK was achieved with ca. 0.2 wt% Pd and size of Pd particles of ca. 3–5 nm.

76 citations


Patent
17 Dec 2001
TL;DR: In this paper, a process for producing bisphenol A by subjecting phenol and acetone to condensation reaction in the presence of a catalyst composed of an acid type ion exchange resin which is modified in part with a sulfur-containing amine compound is disclosed.
Abstract: There is disclosed a process for producing bisphenol A by subjecting phenol and acetone to condensation reaction in the presence of a catalyst composed of an acid type ion exchange resin which is modified in part with a sulfur-containing amine compound, wherein the ion exchange resin having a modification rate of 10 to less than 20 mol % is used for a methanol concentration in acetone of lower than 250 ppm by weight, and the ion exchange resin having a modification rate of 20 to 65 mol % is used for a methanol concentration in acetone of 250 to 8000 ppm by weight. The above process is capable of producing bisphenol A at high conversion and selectivity by suppressing deterioration of catalytic activity due to methanol as an impurity in acetone.

73 citations


Journal ArticleDOI
TL;DR: The rate data indicate that a direct hydrogen abstraction process dominates for triplet acetone, while a charge-transfer mechanism, namely, exciplex-induced quenching, becomes important for singlet-excited acetone.
Abstract: The fluorescence and phosphorescence quenching of acetone by 13 aliphatic amines has been investigated. The bimolecular rate constants lie in the range of 108−109 M-1 s-1 for singlet-excited acetone and 106−108 M-1 s-1 for the triplet case. The rate data indicate that a direct hydrogen abstraction process dominates for triplet acetone, while a charge-transfer mechanism, namely, exciplex-induced quenching, becomes important for singlet-excited acetone. Pronounced stereoelectronic effects toward H abstraction, e.g., for 1,4-diazabicyclo[2.2.2]octane (DABCO), and significant steric hindrance effects, e.g., for N,N-diisopropyl-3-pentylamine, are observed. A negative activation energy (Ea = −0.9 ± 0.2 kcal mol-1 for triethylamine and DABCO) and the absence of a significant solvent effect on the fluorescence quenching of acetone are indicative of the involvement of exciplexes. Full electron transfer can be ruled out on the basis of the low reduction potential of acetone, which was found to lie below −3.0 V vers...

Journal ArticleDOI
TL;DR: In this article, the authors investigated the reactivity of volatile organic compounds (VOCs) on oxide particles and found that these carbonyl compounds irreversibly adsorb and can, in part, react on the surface to form larger molecular weight compounds.
Abstract: The heterogeneous reactivity of volatile organic compounds (VOCs) on oxide particles has been investigated. Oxide particles composed of the most abundant elements present in the Earth's crust were used to identify potentially important reactions of VOCs on mineral dust. In particular, heterogeneous reactions of acetaldehyde, acetone, and propionaldehyde on α-Al2O3, α-Fe2O3, TiO2, CaO, and SiO2 particle surfaces have been investigated. Fourier transform infrared and UV/visible spectroscopic measurements show that these carbonyl compounds weakly and reversibly adsorbed on SiO2. However, on the more basic and acidic oxides investigated, the data show that these carbonyl compounds irreversibly adsorb and can, in part, react on the surface to form larger molecular weight compounds. The kinetics of the heterogeneous reaction of acetaldehyde, acetone, and propionaldehyde on α-Al2O3, α-Fe2O3, TiO2, CaO, and SiO2 were measured with a Knudsen cell reactor at a gas concentration of 6×1010 molecules/cm3. Using the Brunauer-Emmett-Teller surface area of the powdered sample, initial uptake coefficients were determined to be in the 10−4 to 10−6 range for the adsorption of carbonyl compounds on the oxides at 298 K. By using these values for the uptake coefficient, it is found that the heterogeneous loss of these trace volatile organic compounds is comparable to that due to photolysis and reaction with OH in the middle to upper troposphere. Although surface adsorption can occur, the measured second-order pressure dependence to form higher molecular weight compounds suggests that these reaction products will less likely form under atmospheric conditions.

Journal ArticleDOI
TL;DR: In this paper, the authors conducted experiments with acetic acid and zirconia (ZrO2) catalysts in supercritical water (SCW) (673 K and 25 MPa-40 MPa).
Abstract: Reactions of acetic acid were conducted with alkali (KOH) and zirconia (ZrO2) catalysts in supercritical water (SCW) (673 K and 25 MPa–40 MPa). For comparison, we also conducted the experiments without catalyst and/or water at the same reaction conditions. Decarboxylation of acetic acid with zirconia in supercritical water formed acetone, CO2, and water without forming any other compound. On the other hand, decomposition of acetic acid with alkali produced methane (CH4) and CO2 with acetone. Without water and/or catalyst, the main products were also CO2 and CH4 (without catalyst) or acetone (with ZrO2); however, by-products, such as a water-insoluble compound were formed. The structure of zirconia was changed during reaction in supercritical water. The rate of decarboxylation of acetic acid exerted an effect on the particle size of zirconia. © 2001 Elsevier Science B.V. All rights reserved.

Journal ArticleDOI
TL;DR: In this paper, the adsorption of acetone on the Ge(100)-2 × 1 surface has been investigated using multiple internal reflection infrared spectroscopy and density functional theory quantum chemistry calculations and was found to be under thermodynamic control at room temperature.
Abstract: The adsorption of acetone on the Ge(100)-2 × 1 surface has been investigated using multiple internal reflection infrared spectroscopy and density functional theory quantum chemistry calculations and was found to be under thermodynamic control at room temperature. Acetone undergoes attachment at the carbonyl oxygen with loss of an α hydrogen at room temperature on the Ge(100)-2 × 1 surface to form an enol-like adduct. This so-called ene reaction has not been seen on the Si(100) surface, on which the reaction of acetone is under kinetic control and instead a less thermodynamically favored [2 + 2] addition across the carbonyl bond is observed. At low temperature, acetone adsorbs via dative-bond formation with the surface, which we find to be too weak to remain at room temperature in contrast to the stronger dative bonds formed by amines on the Si(100) and Ge(100) surfaces. There is evidence that the acetone ene product may undergo oxygen migration and insertion into Ge−Ge bonds, especially at elevated surfac...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the short and long-term effect of adding water to acetone and methanol extracts from two marine phytoplankton species, Emiliania hyxleyi and Dunaliella tertiolecta.
Abstract: RPHPLC methods for analysis of photosynthetic pigments (chlorophylls and carotenoids) usually require addition of water to methanol or acetone extracts to prevent distortion of early-eluting peaks corresponding to the more polar compounds. In this work we have investigated the short-(<2 min) and long-term (up to 48 h) effect of adding water to acetone and methanol extracts from two marine phytoplankton species,Emiliania hyxleyi andDunaliella tertiolecta. Solvent extracts were prepared and separated into fractions that were subsequently diluted with water to 90%, 80%, 70%, 60%, 50%, and 40% for methanol, and the same range extended to 30% and 20% for acetone. Changes in pigment concentration with time were followed spectrophotometrically and chromatographically. Losses of pigments as a result of precipitation were clearly observed immediately after dilution of acetone extracts to 60% or less and methanol extracts to 80% or less. For chlorophyll a the most substantial losses were recorded for 50% acetone (up to 27% decrease) and for 70% methanol (31% decrease). This effect increased considerably with time. Only for 90% and 80% acetone were the initial concentrations of all the pigments unchanged after 24h, and even up to 48 h. In contrast, more than 60% and 57% of the initial amounts of chlorophyll a were lost after 24 h in 50% acetone and 70% methanol extracts, respectively. These losses increased to 83% and 60% after 48 h. There was a clear correlation between the polarity of a pigment and the polarity of the solvent at which maximum precipitation occurred. Losses of pigment from pure acetone and methanol extracts with time were also observed, although we attribute these to pigment degradation rather than precipitation. Some of the losses occurring with time can be avoided by use of autosamplers in which the sample can be mixed with water immediately before injection.

Journal ArticleDOI
TL;DR: In this article, surface-phase oxides of niobia on silica substrate ((Nb2O5/SiO2), NS(x)) were used as supports for palladium catalysts for the synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen in liquid phase.
Abstract: The surface-phase oxides of niobia on silica substrate ((Nb2O5/SiO2), NS(x)) were prepared and characterized. Such oxides were used as supports for palladium catalysts. The one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen in liquid phase was also investigated over Pd/NS(x) catalysts. Experimental results indicate that these catalysts were effective for the formation of MIBK; since little of the parallel by-product of isopropanol (IPA) was formed, these catalysts reached selectivities of 88–92% MIBK and 2–3% IPA at 30–35% conversion. The reactivity of Pd/NS(x) declined obviously with an increase of water content that accumulated in a semi-batch reaction system. The water could be partially expelled and the deactivation of catalysts could be improved by using a fixed bed continuous flow reaction system.

Journal ArticleDOI
TL;DR: In this paper, the authors compare the solid and the porous texture of resorcinol-formaldehyde (RF) aerogels prepared by the conventional method (in water and base catalysis) to that of samples obtained by the new method(in acetone and acid catalysis), all other parameters (mass ratio, catalyst concentration R/C, supercritical extraction, pyrolysis conditions) remaining the same.
Abstract: During the last decade, several new precursors have been proposed for the synthesis of organic aerogels In a large majority of cases, the sol–gel reaction is base catalyzed and water is used as the solvent Because of the poor solubility of liquid CO 2 in water, a time consuming two-step exchange is necessary (exchange of water by acetone followed by exchange of acetone by liquid CO 2 ) To eliminate this step, a new process with the solvent acetone was developed Also in order to reduce gelation time, acid catalysis is used The aim of the present work is to compare the solid and the porous texture of resorcinol–formaldehyde (RF) aerogels prepared by the conventional method (in water and base catalysis) to that of samples prepared by the new method (in acetone and acid catalysis), all other parameters (mass ratio, catalyst concentration R/C, supercritical extraction, pyrolysis conditions) remaining the same Determination of pore size distribution (PSD) in different series of organic and pyrolyzed aerogels by thermoporometry and characterization of the solid structure by small-angle X-ray scattering (SAXS) measurements over a wide range of length are reported The main difference between the two series of aerogels lies in the aggregation of the primary particles: the new series prepared in acetone and acid catalysis displays fractal scaling over more than a decade in length, while the conventional one does not It is also shown that thermoporometry yields reliable information for both series of aerogels

Patent
19 Feb 2001
TL;DR: In this article, a β-zeolite catalyst with a SiO2/Al2O3 molar ratio greater than 10:1 was used for the alkylation of benzene.
Abstract: The invention relates to a process for the preparation of cumene by reacting isopropanol or a mixture of isopropanol and propene with benzene in presence of a β-zeolite catalyst having a SiO2/Al2O3 molar ratio greater than 10:1 that can be integrated in a process for preparing phenol, which comprises the stepsI. preparation of cumene as described above, II. oxidation of cumene to cumene hydroperoxide, III. acid-catalyzed cleavage of cumene hydroperoxide to give phenol and acetone and IV. hydrogenation of acetone to form isopropanol.In the reaction of isopropanol with benzene, propene is formed by dehydration of isopropanol simultaneously with the alkylation of benzene to cumene by means of isopropanol and the propene formed is likewise used for the alkylation of benzene to cumene. Formation of n-propylbenzene in this process step according to the invention is barely observed or is in the range below 150 wppm.The s-zeolite catalyst having a SiO2/Al2O3 molar ratio greater than 10:1 exhibits an increased activity in the alkylation of benzene and leads to a higher selectivity in the alkylation, so that the yield in the overall process for preparing phenol can be improved compared to conventional processes.

Journal ArticleDOI
TL;DR: In this article, the photocatalytic oxidation of acetone was studied on TiO2 powder and on a TiO 2 monolayer catalyst anchored on porous Vycor glass (TiO2/PVG) using in situ solidstate nuclear magnetic resonance spectroscopy.

Journal ArticleDOI
TL;DR: In this article, the catalytic combustion of acetone and methyl-ethyl-ketone (MEK) has been studied over a manganese oxide, Mn 2 O 3, and the reactant conversion has been followed as a function of the reaction temperature.
Abstract: The catalytic combustion of acetone and methyl-ethyl-ketone (MEK) has been studied over a manganese oxide, Mn 2 O 3 . The reactant conversion has been followed as a function of the reaction temperature and it has been observed that lower temperatures are required for the combustion of acetone than for MEK. The performance of Mn 2 O 3 in the combustion reactions when alkali and acid ions are added to the oxide has also been investigated. A significant improvement of the catalyst performance is observed when Cs + and Na + are used as additives. The data of the ignition curves have been fitted to a simplified model where both ketone combustion reactions are assumed to have power law rate equations, which are first-order with respect to the corresponding organic molecule and do not depend on the oxygen partial pressure. Differences in the apparent activation energy values estimated with this model for acetone and MEK combustion are significant only when acid ions additives are present.

Journal ArticleDOI
TL;DR: In this article, the acidity constants of tetrazole compounds were determined pH-metrically at 25 °C and at the constant ionic strength I = 0.1 mol dm-3 (KNO3) in pure water as well as in various aqueous mixtures having variable mole fractions (0.05−0.3) of organic solvents.
Abstract: The acidity constants of some tetrazole compounds were determined pH-metrically at 25 °C and at the constant ionic strength I = 0.1 mol dm-3 (KNO3) in pure water as well as in various aqueous mixtures having variable mole fractions (0.05−0.3) of organic solvents. The organic solvents used are methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, and acetone. Generally, the pKa values increase with an increase in the content of the organic solvent. It was concluded that the major effects responsible for this behavior are, in addition to the electrostatic effect, the stabilization of the conjugate base by hydrogen-bonding interactions with solvent molecules and solvent basicity. Effect of molecular structure of tetrazoles on the pKa values is discussed. Moreover, the thermodynamic functions (ΔH, ΔG°, and ΔS°) associated with the ionization process of investigated compounds in a pure aqueous medium are derived and their values are discussed.

Journal ArticleDOI
TL;DR: In this paper, the frequency response characteristics for 21 organic vapours by piezoelectric thickness-shear-mode (TSM) acoustic wave sensors coated with four calixarenes have been investigated.

Journal ArticleDOI
TL;DR: In this article, a crosslinked poly(dimethylsiloxane)-poly(methyl hydrogen siloxane) selective layer with a new laboratory made catalyst agent was used for the pervaporation separation of five organic solvent-water mixtures and swelling experiments in the same feed mixtures.
Abstract: Hydrophobic composite membranes with a crosslinked poly(dimethylsiloxane)-poly(methyl hydrogen siloxane) selective layer were prepared by using a new laboratory made catalyst agent. The pervaporation separation of five organic solvent–water mixtures was carried out with these composite membranes, together with swelling experiments in the same feed mixtures. The volatile organic compounds employed were ethanol, methanol, 1-butanol, acetone, and ethyl acetate. The pervaporation and swelling experiments revealed that both the 1-butanol and the ethyl acetate solutions showed the highest affinity for the composite membrane. When these components were employed as feed solutions, the membranes showed both high selectivity and high permeation. Mechanical–dynamical experiments of swollen and nonswollen composite membranes were also performed. The relaxation spectra were analyzed in terms of the interaction of the components of the different mixtures with the composite membrane, and the free volume corresponding to the each sample was obtained. Once the membranes had reached an equilibrium swelling, a decrease in the free volume was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 546–556, 2001

Journal ArticleDOI
TL;DR: In this paper, the Verbascum stalk mill was converted to liquid products by using organic solvents, such as methanol, ethanol and acetone, with catalysts (10% NaOH or ZnCl 2 ) and without catalyst in an autoclave at temperatures of 533, 553 and 573 K.

Journal ArticleDOI
TL;DR: In this article, the performances of cellulose acetate membranes prepared with casting solutions, with acetone, dimethylformamide (DMF), and N-methylpyrrolidone (NMP) as solvents, were studied in a series of methanol/methyl tertiary butyl ether separation experiments.
Abstract: The performances of cellulose acetate membranes prepared with casting solutions, with acetone, dimethylformamide (DMF), and N-methylpyrrolidone (NMP) as solvents, were studied in a series of methanol/methyl tertiary butyl ether separation experiments. The flux and selectivity of the membrane samples were affected by the type of solvent used to prepare the casting solution. The sample with DMF consistently gave the highest selectivity and lowest flux, followed by the samples with NMP and acetone. The differences in the performances were attributed to the effects of the volatility and evaporation rates of the solvents. Scanning electron microscopy and atomic force microscopy techniques were used for comparing the morphologies of the membranes. In addition, we used Raman spectroscopy as a novel technique to study the sorption selectivities of the membrane samples prepared with the three different solvents. In a parallel study, the relation between the polymer concentration in the casting solution and the morphology and performance of the membrane samples was studied. Under similar preparation conditions, the morphology of the membrane changed from being porous to being dense when the membrane was prepared with casting solutions with increasing polymer concentration. Also, the selectivity increased and the permeability decreased with increasing polymer concentration in the casting solution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2882–2895, 2001

Journal ArticleDOI
TL;DR: The overall findings indicated that additional increases in acetone concentration resulted in an inhibition of tyrosinase activity.
Abstract: The enzymatic activity of mushroom tyrosinase was investigated using catechin as substrate in selected organic solvent media. The results showed that optimal tyrosinase activity was obtained at pH 6.2, 6.6, 6.0 and 6.2 in the organic solvent media of heptane, toluene, dichloromethane, and dichloroethane, respectively, and at a temperature between 25°C and 27.5°C. In addition, the kinetic studies showed that the Km values were 5.38, 1.03, 2.52 and 4.03 mM, for the tyrosinase-catechin biocatalysis in the reaction media of heptane, toluene, dichloromethane, and dichloroethane, respectively, while the corresponding Vmax values were 1.22×10−3, 0.33×10−3, 1.47×10−3 and 1.20×10−3 δA per μg protein per second, respectively. The use of acetone as co-solvent for the tyrosinase-catechin biocatalysis showed that acetone concentrations ranging from 5% to 30% (v/v) in the heptane reaction medium produced a decrease of 4.3% to 96.7% in tyrosinase activity. The results also indicated that the presence of 12.5% acetone in the reaction medium of dichloromethane, and 22.0% in those of toluene and dichloroethane produced a maximal increase of 42.6%, 92.1% and 71.8%, respectively, in tyrosinase activity. However, the overall findings indicated that additional increases in acetone concentration resulted in an inhibition of tyrosinase activity.

Journal ArticleDOI
TL;DR: In this paper, a mannose and lauric acid was synthesized at 50°C using the immobilized lipase Novozym® 435 in four water-miscible organic solvents, with various water contents.

Journal ArticleDOI
TL;DR: In this paper, the asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol, a precursor for a key intermediate of an important class of drugs, was achieved by reduction of the corresponding ketone using an acetone powder of Geotrichum candidum with 98% ee and 94% yield based on the starting amount of ketone.
Abstract: The asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol, a precursor for a key intermediate of an important class of drugs, was achieved by reduction of the corresponding ketone using an acetone powder of Geotrichum candidum with 98% ee and 94% yield based on the starting amount of ketone.

Journal ArticleDOI
TL;DR: During enrichments to search for soil bacteria that form the volatile ketones, acetone and butanone, pure cultures of Pseudomonas aureofaciens, P. fluorescens, and P. putida that excrete the β-keto-acid, 3-oxopentanoate (3-OPA) were isolated.
Abstract: During enrichments to search for soil bacteria that form the volatile ketones, acetone and butanone, we isolated pure cultures of Pseudomonas aureofaciens, P. fluorescens, and P. putida that excrete the beta-keto-acid, 3-oxopentanoate (3-OPA), when grown on heptanoic acid as carbon source. Analysis of 3-OPA used enzymatic decarboxylation by acetoacetate decarboxylase to yield butanone, which was detected by headspace gas chromatography. The formation of 3-OPA was strongly dependent on heptanoic acid concentration, the level of oxygen, and the state of growth, and was not seen with even-chain or other odd-chain fatty acids. Uptake of 3-OPA during stationary phase of growth is probably related to polyhydroxyalkanoate (PHA) formation in these isolates. A model for formation and release of 3-OPA is proposed.

Journal ArticleDOI
TL;DR: In this article, the rate constants for the reaction of superoxide O-2 with various substrates were obtained through stationary electrode polarography theory and technique, and the mechanism of the reaction was proposed as O-3 + AH k2O, AHk2k-1 k′ [O2H + AH]-, k-2→O 2H + A- with k1 = 109 M-1 s-1 and k-1 = 108 -109 s- 1.
Abstract: Rate constants for the reaction of superoxide O-2 with various substrates were obtained through stationary electrode polarography theory and technique. In solvent acetonitrile, the substrate and the rate constants of the reaction O-2 + AH-k2→Product, are, AH = isopropanol (k2 < 0.01 M-1 s-1); ethanol (k2 = 1.42 × 102 M-1 s-1); methanol (k2 = 1.1 × 107 M-1 s-1), H2O (k2 = 1.0 × 105 M-1 s-1). In MeCN, O-2 was found to be rather unreactive towards glucose and acetone but it reacts with fructose and sucrose catalytically. However, in DMF2, O-2reacts with glucose and fructose with k2 order of 105 M-1 s-1. The mechanism of the reaction of O-2 with the substrates (AH) is proposed as O-3 + AH k2O, AHk2k-1 k′ [O2H + AH]-, k-2→O2H + A- with k1 = 109 M-1 s-1 and k-1 = 108 -109 s-1. With these values of k-1 and k1, k′ k2(obs). The reversible E1/2 for O2 + e O-2 in various solvents: MeCN, acetone, isopropanol, methanol, H2O were obtained either directly from the reversible voltammogram or from experimental voltammograms and the rate constants obtained (as above) using stationary electrode polargraphy theory; E1/2 being -0.82 (MeCN),-0.85 (acetone),-0.72 (isopropanol);-0.66 (MeOH),-0.56 (H2O) vs SCE.