Showing papers on "Acetone published in 2010"
TL;DR: In this paper, a comparative study of the adsorption and photoinduced degradation of acetone and acetic acid on thin films of anatase, brookite, and rutile TiO2 nanoparticles is presented.
Abstract: A comparative study of the adsorption and photoinduced degradation (PID) of acetone and acetic acid on thin films of anatase, brookite, and rutile TiO2 nanoparticles is presented. The materials were thoroughly characterized by a wide range of methods, including X-ray diffraction, transmission electron microscopy, and Raman and UV−vis spectroscopies. In situ FTIR transmission spectroscopy was used to follow adsorption and PID reactions. Molecular adsorption of acetone and acetic acid is observed on anatase and brookite, whereas significant dissociation occurs on rutile. It is inferred that adsorbate−surface interaction increases in the order anatase < brookite < rutile, favoring formation of bridge-bonded species on rutile (acetate and formate). Illumination with simulated solar light readily dissociates acetic acid and acetone on all TiO2 samples and produces polymorph-specific intermediate surface species, including acetate, formate, carbonate, and water. PID of surface coordinated acetate is rate determ...
167 citations
TL;DR: In this article, the effect of nontoxic Si doping on the e-phase content and crystal and grain sizes was investigated and correlated to the acetone sensing performance of WO3 nanoparticles.
Abstract: Acetone in the human breath is a key marker for noninvasive diagnosis of diabetes. Here, sensing films of pure and SiO2-doped WO3 nanoparticles have been made, directly deposited and in situ annealed onto interdigitated electrodes by scalable flame aerosol technology. A unique innovation here is that these films consist of e-WO3, a metastable phase that has a high selectivity to acetone. The effect of nontoxic Si doping on the e-phase content and crystal and grain sizes was investigated and correlated to the acetone sensing performance of these films. The thermal stability of these materials was characterized as well, revealing a unique opportunity for reliable sensing of acetone and noninvasive diagnostics of diabetes. An optimal doping level with 10 mol % SiO2 resulted in highly sensitive and highly selective acetone sensors down to 20 ppb.
151 citations
TL;DR: In this paper, a response surface methodology using two food grade solvents, acetone and ethanol, was used to optimise antioxidant extraction from industrially generated apple pomace.
111 citations
TL;DR: MAC (methyl addition/cyclization) has a unique capacity to induce the sequential growth of hexagonal networks of sp2 carbons from all fusing sites of a PAH, and was found capable of answering an important question in PAH growth, which is expansion of the CT → CP → hexagonal network for which other reported mechanisms are inefficient.
109 citations
TL;DR: In this paper, the results of both Fourier transform infrared spectroscopy and zeta potential measurements confirm that a readily apparent number of Lewis acid sites composed of mainly carboxylic acid and cyclic acid anhydrides were derived on the surface of thermally oxidized nanodiamond (T-ND).
108 citations
TL;DR: The experimental delignification capacity of the aqueous organic solvents clearly reflected the proximity of their delta-value to that of lignin as well as the hydrogen-bondingcapacity of the solvent-water mixtures.
107 citations
TL;DR: In this article, ZnO thin films were prepared by reactive RF sputtering on thermally oxidized Si for gas sensing applications, and three VOC vapors were chosen to investigate the response behavior of the prepared ZnOs.
95 citations
TL;DR: In this article, the solubilities of NaCl, KCl, LiCl, and LiBr in pure methanol, ethanol, and acetone were measured over a temperature range from 293.15 to 333.15 K.
Abstract: The solubilities of NaCl, KCl, LiCl, and LiBr in pure methanol, ethanol, and acetone were measured over a temperature range from 293.15 to 333.15 K. Furthermore salt solubilities in the mixed solvents (water + methanol, water + ethanol, water + acetone, methanol + ethanol, methanol + acetone, ethanol + acetone) were determined at 313.15 K. For a few systems solubility data are reported for the first time. In a few cases a comparison with published data stored in the Dortmund Data Bank (DDB)(1) showed disagreement. The LIQUAC model was used to correlate the experimental data. The calculated salt solubilities are in good agreement with the experimental results for the systems NaCl + water + methanol and KCl + water + methanol.
83 citations
TL;DR: It is shown that a trace amount of residual acetone in the precipitated protein, can, after proteolysis, lead to selective modification of peptides predominantly those in which a glycine residue is the second amino acid, probably generating a relatively stable derivative that, under gas phase conditions, generates a y(1) ion of the same mass as proline.
Abstract: Acetone precipitation is a common method for precipitation and concentration of proteins. We show here that a trace amount of residual acetone in the precipitated protein, can, after proteolysis, lead to selective modification of peptides predominantly those in which a glycine residue is the second amino acid, probably generating a relatively stable derivative that, under gas phase conditions, generates a y(1) ion of the same mass as proline. This modification is detectable by either MALDI-ToF or ESI-ion trap mass spectrometry and under normal sample preparation conditions is incomplete. The derivatization occurs in the condensed phase and is sufficiently stable that the modified peptide can elute on reversed phase chromatography at a different time to the unmodified peptide. Acetone precipitation is such a commonly used procedure in protein sample preparation for proteomics that some caution may be warranted. A significant number of peptides (about 5% of a typical proteome) meet the requirements for this reaction and could, therefore, change the outcome of studies.
77 citations
TL;DR: Indoor air concentrations of fifteen volatile per- and polyfluorinated compounds (PFCs) were determined in residential and nonresidential indoor air environments indicating indoors air environments as sources for PFCs to the atmosphere.
Abstract: Indoor air concentrations of fifteen volatile per- and polyfluorinated compounds (PFCs) (five fluorotelomer alcohols (FTOHs), three fluorotelomer acrylates (FTAs), three perfluorinated sulfonamido ethanols (FASEs), and three perfluorinated sulfonamides (FASAs)) were determined in residential and nonresidential indoor air environments. Air samples were taken with passive samplers, consisting of XAD-4 impregnated polyurethane foam (PUF) disks in steel housings. Impregnated PUF disks were extracted by fluidized bed extraction (FBE) using methyl-tert-butyl ether/acetone (1:1) and analyzed by gas chromatography−mass spectrometry. Total PFC indoor air concentrations ranged from 8.2 to 458 ng m−3. Individual PFC concentrations were between 42 pg m−3 (6:2 FTA) and 209 ng m−3 (8:2 FTOH). Concentrations of total FTOHs, FTAs, and FASAs + FASEs ranged from 0.2 to 152 ng m−3 (FTAs), from 3.3 to 307 ng m−3 (FTOHs), and from 4.4 to 148 ng m−3 (FASAs + FASEs). Most elevated individual, group, and total PFC concentrations...
75 citations
TL;DR: In this article, the solubility of butyl paraben (butyl 4-hydroxybenzoate) has been determined in methanol, ethanol, propanol, acetone, ethyl acetate, and acetonitrile in the temperature range of (10 to 50) °C.
Abstract: The solubility of butyl paraben (butyl 4-hydroxybenzoate) have been determined in methanol, ethanol, propanol, acetone, ethyl acetate, and acetonitrile in the temperature range of (10 to 50) °C by the gravimetric method. The order of the solubility of butyl paraben in the different solvents as mass fraction at 20 °C is: methanol > ethanol > acetone > propanol > ethyl acetate > acetonitrile. In terms of mole fraction solubility, the corresponding order is acetone > propanol > ethanol > ethyl acetate > methanol > acetonitrile, which shows that both nonpolar and polar groups of the paraben molecule influence the solubility in the different solvents.
TL;DR: In this article, the adsorption and tautomerization reaction of acetone in H-FER, H-ZSM-5, and H-MCM-22 zeolites was studied using full quantum calculations at the M06-2X/6-311+G(2df,2p) level of theory.
Abstract: The adsorption and tautomerization reaction of acetone in H-FER, H-ZSM-5, and H-MCM-22 zeolites has been studied using full quantum calculations at the M06-2X/6-311+G(2df,2p) level of theory. The combination of a large quantum cluster and this meta-hybrid density functional results in reasonably accurate adsorption energies of −26.9, −28.1, and −23.9 kcal/mol for acetone adsorption in H-FER, H-ZSM-5, and H-MCM-22, respectively. Due to the acidity of the zeolite and the framework confinement effect, the tautomerization of acetone proceeds through a much lower activation barrier than in the isolated gas phase or in the presence of water molecules alone. The activation energies are calculated to be 24.9, 20.5, and 16.6 kcal/mol in H-FER, H-ZSM-5 and H-MCM-22, respectively. The endothermic reaction energy decreases with increasing of the zeolite pore sizes and amounts to 22.7, 17.6, and 15.9 kcal/mol for the reaction in H-FER, H-ZSM-5 and H-MCM-22, respectively. In addition, the adsorbed acetone enol is found...
TL;DR: An effective organocatalytic asymmetric aldol reaction of acetone to β,γ-unsaturated α-keto ester has been developed in the presence of 9-amino (9-deoxy)-epicinchona alkaloid and 4-nitrobenzoic acid.
TL;DR: The rate coefficients for reactions of OH with acetone, methyl ethyl ketone (MEK) and dimethyl ether (DME) have been measured in the temperature range 86-112 K using a pulsed Laval nozzle apparatus and large increases in k at lower temperatures were observed.
Abstract: The rate coefficients (k) for reactions of OH with acetone, methyl ethyl ketone (MEK) and dimethyl ether (DME) have been measured in the temperature range 86–112 K using a pulsed Laval nozzle apparatus. Large increases in k at lower temperatures were observed, with k86K/k295K = 334 for acetone, and k93K/k295K = 72 and 3, for MEK and DME respectively. A mechanism involving the formation of a hydrogen bonded complex prior to an overall barrier on the potential energy surface is proposed to explain this behaviour.
TL;DR: In this paper, a method for the aldol condensation of acetone with aromatic and aliphatic aldehydes, using morpholinium trifluoroacetate as a catalyst, is described.
Abstract: We report a highly efficient, general and practical method for the aldol condensation of acetone with aromatic and aliphatic aldehydes, using morpholinium trifluoroacetate as a catalyst.
TL;DR: In this paper, a simple one-step hydrothermal route to Li1+xMn2−yO4 spinel compounds (x = 0.01-0.06, y =0.02−0.09) via reduction of commercially available potassium permanganate with common organic reductants (alcohols, acetone, hex-1-ene, and isobutyraldehyde) in lithium hydroxide aqueous solutions is developed.
Abstract: A simple one step hydrothermal route to Li1+xMn2−yO4 spinel compounds (x = 0.01–0.06, y = 0.02–0.09) via reduction of commercially available potassium permanganate with common organic reductants (alcohols, acetone, hex-1-ene, and isobutyraldehyde) in lithium hydroxide aqueous solutions is developed. The cubic spinel phase with no other impurities can be isolated after short reaction times (∼5 h) at the relatively low temperature of 180 °C. Scanning electron microscopy imaging reveals that the crystalline products have a distribution of sizes; the majority of the sample is composed of smaller particles between 10 and 30 nm. However, there are noticeably larger 100–300 nm interspersed particles—more prevalent in reactions with acetone and isobutyraldehyde. In corresponding benchtop test reactions, UV-Vis spectroscopy shows that the disappearance of MnO4− occurs more rapidly when acetone and isobutyraldehyde are used as reducing agents. Cyclic voltammetry performed on our spinels prepared via hydrothermal synthesis shows three reversible redox processes: a wave with E1/2 of ∼2.9 V (vs. Li/Li+) and two close waves between 4.05 and 4.15 V. Galvanostatic cycling of a cell composed of Li1.02Mn1.96O4 prepared from the oxidation of acetone between 3.5 and 4.4 V demonstrates a specific capacity of 104 mA h g−1 on first discharge, with ∼87% capacity retention (90 mA h g−1) after 100 cycles. The specific capacity of all samples correlates with the rate of disappearance of MnO4− observed in our benchtop reactions, providing a facile way to control particle size and electrochemical behavior.
TL;DR: The allelopathic potential induced by low concentrations of the acetone fraction and vanillic acid stimulated the germination and growth of tomato and had stimulating effects on the activity of some antioxidant enzymes.
Abstract: From the active acetone fraction of Chenopodium murale, vanillic acid was isolated and identified, based on 1H and 13C nuclear magnetic resonance spectral analyses. Free phenolic compounds inside the active acetone were qualified and quantified by using high performance liquid chromatography analysis, which revealed the presence of seven compounds with an abundance of vanillic and p-hydroxybenzoic acids. The allelopathic potential of the acetone fraction and vanillic acid was evaluated through laboratory bioassays against tomato plants. Our results showed that the allelopathic potential induced by low concentrations of the acetone fraction and vanillic acid stimulated the germination and growth of tomato and had stimulating effects on the activity of some antioxidant enzymes. We observed an enhancement in the activity of catalase, peroxidase, superoxide dismutase, and polyphenol oxidase, as well as the content of soluble protein and phenolic glycoside. Meanwhile, the levels of free phenolic compounds, H2O2, and lipid peroxidation decreased. The highest stimulations were recorded at 50 p.p.m. of acetone fraction and 0.5 p.p.m. of vanillic acid. In contrast, the highest concentrations exerted negative effects on all the measured parameters to record the maximum value of inhibition at 400 p.p.m. of acetone fraction and 4 p.p.m. of vanillic acid. These results proved the antioxidative effects of active acetone and vanillic acid at low concentrations and their potent use as a stimulator for tomato germination and growth.
TL;DR: In this article, both acidic and basic carbon based catalysts have been prepared by chemical activation of olive stone waste with H3PO4 and H2SO4 of acid character and Ca(OH)2 and Ba(OH)-2 of basic character.
TL;DR: In this article, the adsorptions of acetone on various Bronsted and Lewis acid sites (from weak acid to superacid) are theoretically studied, in order to elucidate the quantitative relationship between C-13 chemical shifts of the acetone and intrinsic acid strength of solid acids.
Abstract: Adsorption of basic probe molecules is one of the widely used methods to characterize the acid strength of solid acids. In this contribution, the adsorptions of acetone on various Bronsted and Lewis acid sites (from weak acid to superacid) are theoretically studied, in order to elucidate the quantitative relationships between C-13 chemical shifts of acetone and intrinsic acid strength of solid acids. The Bronsted acid sites are represented by a series of 8T zeolite models with varying terminal Si-H bond lengths, and the different extents of acidic proton transfer from these acid sites to acetone are revealed explicitly. We found that three adsorption conformations (hydrogen-bonded, proton-shared, and ion-pair) exist for acetone, and concurrently, a correlation of three-broken lines is obtained for the C-13 chemical shift of acetone versus the deprotonation energy (DPE). The correlation can be used as a scale for quantitatively measuring the Bronsted acid strength of solid acids. A threshold of 245 ppm is determined for superacidity, in good agreement with the experimental value (244 ppm). The Lewis acid sites are modeled by tricoordinate framework aluminum species and various extra-framework aluminum cations or neutral species such as Al3+, AlO+, AlOH2+, Al(OH)(2)(+), Al(OH)(3), and AlOOH. We found that acetone is coordinately adsorbed on the aluminum atoms of Lewis acid sites and that the C-13 chemical shift of acetone is almost linear to the lowest unoccupied molecular orbital (LUMO) energy of the acid sites.
TL;DR: A refinement of the assay that utilizes headspace analysis is reported, which minimizes the number of transfers and decreases sample preparation time and instrument run time.
TL;DR: The results suggested that P. ostreatus may have potential as a natural antioxidant and tyrosinase inhibitory ability, whereas the acetone and hot water extracts showed moderate activity at the concentrations tested.
Abstract: We evaluated the antioxidant activity and tyrosinase inhibitory effects of Pleurotus ostreatus fruiting bodies extracted with acetone, methanol, and hot water. The antioxidant activities were tested against β-carotene-linoleic acid, reducing power, 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity, and ferrous chelating ability. Furthermore, phenolic acid and flavonoid contents were also analyzed. The methanol extract showed the strongest β-carotene-linoleic acid inhibition as compared to the other exracts. The acetone extract (8 mg/mL) showed a significantly high reducing power of 1.54 than the other extracts. The acetone extract was more effective than other extracts for scavenging on 1,1-diphenyl-2-picrylhydrazyl radicals. The strongest chelating effect (85.66%) was obtained from the acetone extract at 1.0 mg/mL. The antioxidant activities of the extracts from the P. ostreatus fruiting bodies increased with increasing concentration. A high performance liquid chromatography analysis detected seven phenolic compounds, including gallic acid, protocatechuic acid, chlorogenic acid, naringenin, hesperetin, formononetin, and biochanin-A in an acetonitrile and 0.1 N hydrochloric acid (5 : 1) solvent extract. The total phenolic compound concentration was 188 µg/g. Tyrosinase inhibition of the acetone, methanol, and hot water P. ostreatus extracts increased with increasing concentration. The results revealed that the methanol extract had good tyrosinase inhibitory ability, whereas the acetone and hot water extracts showed moderate activity at the concentrations tested. The results suggested that P. ostreatus may have potential as a natural antioxidant.
TL;DR: In this article, the influence of organic solvents with different polarity (methanol, acetone, acetic acid, toluene, and n-hexane) on the filtration performance of STARMEM membranes is reported.
Abstract: The major problem reported for commercially available membranes is their limited chemical stability in organic solvents. This article reports the influence of organic solvents with different polarity (methanol, acetone, acetic acid, toluene, and n-hexane) on the filtration performance of STARMEM membranes. These membranes are specified to be compatible with the solvents used. The pure toluene flux of these membranes and the rejection of azo dyes (Sudan Black and Rhodanile Blue) were measured before and after a week of exposure to one of the above-mentioned solvents. The results show that the structure of the membrane changed after pretreatment with polar solvents (methanol, acetone, acetic acid) and that the membrane performance shifts toward lower rejections with higher solvent flux. Nonpolar solvents do not change the polyimide membrane performances significantly. Contact angle measurements on new and solvent-treated membranes show that organic solvents change the hydrophobicity of polymeric membrane su...
TL;DR: In this article, the composition of binary solvent mixtures (ketones, methyl ethyl ketone (MEK), and alcohols) was optimized with respect to control of fiber felt morphology.
Abstract: Non-woven structures of cellulose acetate (CA) fibres of 90 nm–5 μm in diameter (spinning parameters 90 nm beaded fibres: 12% CA in EtOH-DMSO 1/1, 22 kV, 30 cm, 0.5 mL/h; maximum 5 μm diameter fused fibres spun with 14% CA in Ac-BenzOH 2/1, 22 kV, 24 cm, 13 mL/h) were produced by electrospinning. On the basis of Hansen solubility theory, composition of binary solvent mixtures (ketones—acetone, methyl ethyl ketone (MEK), and alcohols—benzyl alcohol, propylene glycol and dimethylsulphoxide) was optimized with respect to control of fibre felt morphology. Fibre networks of high packing density were obtained with binary low-volatile alcohols/MEK solvent mixtures, a decreased spinning distance and an increased feed rate. Substituting MEK by acetone in the solvent mixture resulted in the formation of nanofibre felt with a low degree of fibre cross-links. Thus, solvent control is a key aspect for control of electrospun fibre felt structures, which may serve as scaffolds for tissue engineering.
TL;DR: The experimental results show that molecular volume has less influence than solubility and molecular polarity for these organic solvent for pervaporation performance, and the selectivity of PDMS membrane to ethyl acetate is relative high due to good solubilities and diffusion of ethylacetate molecules in polymer.
Abstract: As an energy-efficient alternative to distillation, pervaporation has been widely combined with fermentation to remove organic compounds from their dilute solutions in a fermentation broth. In this work, the organic permselective composite membrane is prepared by coating polydimethylsiloxane (PDMS) cross-linked with n-heptane on the substrate of polytetrafluoroethylene(PTFE) membrane. The separation behavior is studied in different dilute organic solutions, which include acetone dilute solution, butanone dilute solution, cyclohexanone dilute solution, ethanol dilute solution, isopropanol dilute solution, n-butyl alcohol dilute solution, acetic acid dilute solution, and ethyl acetate dilute solution. Most of these solutions are main reaction products or by-products from fermentation process. The effects of solubility of organics in the membrane, molecular weight, and polarity of the organics on the pervaporation performance are investigated. The effects of operating temperature and organic concentration in the feed solutions on the performance of composite membrane are studied as well. The experimental results show that molecular volume has less influence than solubility and molecular polarity for these organic solvent. The selectivity of PDMS membrane to ethyl acetate is relative high due to good solubility and diffusion of ethyl acetate molecules in polymer.
TL;DR: In this article, the authors studied steam reforming reactions of reagent ethanol and of biomass-derived ethanol (bio-ethanol) over Pt catalysts supported on ZrO2.
Abstract: Steam reforming reactions of reagent ethanol and of biomass-derived ethanol (bio-ethanol) over Pt catalysts supported on ZrO2 were studied. For steam reforming reactions at 673 K of reagent ethanol with an H2O/C2H5OH molar ratio = 3, the initial H2 yields were 20–29%. The major carbon-containing products were CH4, CO2, and CO. Small amounts of acetaldehyde, acetone, and ethylene were produced, showing that the partial ethanol steam reforming reaction (C2H5OH + H2O → CH4 + CO2 + 2H2) occurred competitively with the ethanol decomposition reaction (C2H5OH → CH4 + CO + H2). H2 formation for bio-ethanol was less than that obtained with reagent ethanol under the same conditions. The catalytic activity for the partial steam reforming reaction decreased rapidly; a similar decrease in the activity of the ethanol decomposition reaction was observed. The poisoning effect of sulfur compounds on the Pt sites was responsible for the deactivation of the bio-ethanol steam reforming reaction.
TL;DR: In this article, various concentrations of phenol and acetone were added into CHP for determination of thermal hazards, and differential scanning calorimetry (DSC) tests were used to obtain the parameters of exothermic behaviors under dynamic screening.
Abstract: Cumene hydroperoxide (CHP) being catalyzed by acid is one of the crucial processes for producing phenol and acetone globally. However, it is thermally unstable to the runaway reaction readily. In this study, various concentrations of phenol and acetone were added into CHP for determination of thermal hazards. Differential scanning calorimetry (DSC) tests were used to obtain the parameters of exothermic behaviors under dynamic screening. The parameters included exothermic onset temperature (T
0), heat of decomposition (ΔH
d), and exothermic peak temperature (T
p). Vent sizing package 2 (VSP2) was employed to receive the maximum pressure (P
max), the maximum temperature (T
max), the self-heating rate (dT/dt), maximum pressure rise rate ((dP/dt)max), and adiabatic time to maximum rate ((TMR)ad) under the worst case. Finally, a procedure for predicting thermal hazard data was developed. The results revealed that phenol and acetone sharply caused a exothermic reaction of CHP. As a result, phenol and acetone are important indicators that may cause a thermal hazard in the manufacturing process.
TL;DR: During transient-state experiments, increasing the overall pollutant load by almost 3-fold, resulted in a sudden drop of removal efficiency, but still high elimination capacities were maintained, and periodic microscopic observations revealed that the originally inoculated Sporothrix sp.
Journal Article•
TL;DR: In this paper, the solubility of caffeine in water, ethyl acetate, ethanol, carbon tetrachloride, methanol, chloroform, dichloromethane and acetone were measured by a gravimetrical method from (298 to 323) K.
Abstract: −− The solubility of caffeine in water, ethyl acetate, ethanol, carbon tetrachloride, methanol, chloroform, dichloromethane and acetone were measured by a gravimetrical method from (298 to 323) K and the solubility data was correlated against temperature. The solubility of caffeine in chloroform and dichloromethane was high compared with other solvents Keywords−− Caffeine; Solubility; Solvents; Correlation.
TL;DR: In this paper, the effects of the operation temperature and feed composition on the pervaporation performance were investigated and the differences of the separation performance between the ternary mixture and binary mixture were also studied through evaluating the permeability coefficient, the swelling degree of the membrane, and the activity coefficient.
Abstract: In this paper, hydroxyterminated polybutadiene-based polyurethaneurea (HTPB-PU) pervaporation membranes were prepared by phase inversion and used for recovering acetone and n-butanol from dilute aqueous solutions. The effects of the operation temperature and feed composition on the pervaporation performance were investigated. The differences of the separation performance between the ternary mixture and binary mixture were also studied through evaluating the permeability coefficient, the swelling degree of the membrane, and the activity coefficient. The results indicated that a complex “coupling effect” occurred in the ternary mixture. The pervaporation performance for the ternary mixture was superior to that for the binary mixture because of the permeant-permeant and permeant-membrane interactions. A high selectivity towards acetone and n-butanol was obtained. Acetone and butanol were condensed from 1.5 to 11.9 wt% and 3.0 to 43.5 wt% at 40°C for the ternary mixtures, respectively. Furthermore, potential ...
Patent•
14 Sep 2010
TL;DR: In this paper, a method for the production of 3-hydroxy-3-methylbutyric acid from acetone and a compound which provides an activated acetyl group was described.
Abstract: Described is a method for the production of 3-hydroxy-3-methylbutyric acid (also referred to as beta-hydroxyisovalerate or HiV) from acetone and a compound which provides an activated acetyl group comprising the enzymatic conversion of acetone and a compound which provides an activated acetyl group into 3-hydroxy-3- methylbutyric acid The conversion makes use of an enzyme which is capable of catalyzing the formation of a covaient bond between the carbon atom of the oxo (ie the C=O) group of acetone and the methyl group of the compound which provides an activated acetyl group Preferably, the enzyme employed in the process is an enzyme with the activity of a HMG CoA synthase (EC 23310) and/or a PksG protein and/or an enzyme with the activity of a C-C bond cleavage/condensation lyase, such as a HMG CoA lyase (EC 4134) Also described are organisms which are able to produce 3-hydroxy-3-methylbutyπc acid from acetone, a compound which provides an activated acetyl group, the use of the above-mentioned enzymes and organisms for the production of 3-hydroxy-3-methylbutyric acid as well as the use of acetone for the production of 3-hydroxy-3-methylbutyric acid