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Представлены результаты исследования тандемных реакций - альдольно-крото­новой конденсации и гидрирования по механизму гидридного переноса в смеси ацетон-изопропанол на катализаторе МgSnО3 при 300-400 °С и 12,0 МПа. При этих условиях смесь субстратов и продуктов реакции находится в сверхкритиче­ском состоянии. Рассмотрены зависимости от температуры степени превращения реагентов (ацетона и изопропанола) и селективности по продуктам конденсации и гидрирования. Установлено, что гидрирование продуктов альдольно-кротоновой конденсации ацетона протекает путем присоединения водорода от молекул изопропанола по С=О-связям изомерных оксидов мезитила и форонов и сопровож­дается реакциями дегидратации спиртов и изомеризации двойной С=С-связи. Оптимальные условия образования продуктов гидрирования карбонильной груп­пы - 350 °С и соотношение ацетон: изопропанол = 7 : 3. При соотношении ацетон: изопропанол = 1 : 1 в продуктах превращения оксида мезитила преоблада­ют метилпентадиены. Реакция гидрирования протекает также с участием изофо­ронов - продуктов конденсации трех молекул ацетона., The results of a study of tandem reactions - aldol-crotonic condensation and hydrogenation by the mechanism of hydride transfer in acetone-isopropanol mixtures on a МgSnО3 catalyst at 300-400 °C and 12.0 MРa are presented. In these conditions the mixture ofreactants (acetone and isopropanol) and reaction products is in the supercritical state. The temperature dependences of the reactants conversion and the selectivity for condensation and hydrogenation products are considered. It has been established that the hydrogenation of the acetone aldol-crotonic condensation products proceeds by the addition of hydrogen from isopropanol molecule to the C=O-bonds of isomeric mesityl and phorone oxides and is accompanied by the dehydration of alcohols and the isomeriza­tion of double C=C-bonds. The optimal conditions for the formation of the carbonyl group hydrogenation products are 350°C and the ratio acetone : isopropanol = 7 : 3. At the acetone to isopropanol ratio 1 : 1, methylpentadienes dominate in the products of mesityl oxide conversion.The hydrogenation reaction also proceeds with the participation of isophorones, the condensation products of three acetone molecules., Сверхкритические Флюиды: Теория и Практика, Выпуск 4 (4) 2023, Pages 71-83

Targeted tricyclic quinolines were prepared from the corresponding aminoindazolic and indolic derivatives as starting materials using two comparative methods; conventional heating and microwave irradiation. We noticed that the syntheses of 5-amino-1-methylindazole and 5-aminoindole were abandoned due to their conversion to fluorescent products one week after free contact with air and acetone. As a result of this finding, we decided to condense the relevant amine with acetone or mesityl oxide to confirm our hypothesis. We show that the amine is converted to the derived quinoline through these condensation processes. Subsequently, this reaction was extended to the aminoindazole derivatives of positions 5 and 6, yielding the appropriate quinoline derivatives. Similarly, 5-aminoindole exhibited the same reactivity. By applying the corresponding NMR and centesimal techniques, the resulting structures were identified.

Isolated hafnium (Hf) sites were prepared on Silicalite-1 and SiO2 and investigated for acetone conversion to isobutene. Characterization by IR, 1H MAS NMR, and UV-vis spectroscopy suggests that Hf atoms are bonded to the support via three O atoms and have one hydroxyl group, i.e, (≡SiO)3Hf-OH. In the case of Hf/Silicalite-1, Hf-OH groups hydrogen bond with adjacent Si-OH to form (≡SiO)3Hf-OH···HO-Si≡ complexes. The turnover frequency for isobutene formation from acetone is 4.5 times faster over Hf/Silicalite-1 than Hf/SiO2. Lewis acidic Hf sites promote the aldol condensation of acetone to produce mesityl oxide (MO), which is the precursor to isobutene. For Hf/SiO2, both Hf sites and Si-OH groups are responsible for the decomposition of MO to isobutene and acetic acid, whereas for Hf/Silicalite-1, the (≡SiO)3Hf-OH···HO-Si≡ complex is the active site. Measured reaction kinetics show that the rate of isobutene formation over Hf/SiO2 and Hf/Silicalite-1 is nearly second order in acetone partial pressure, suggesting that the rate-limiting step involves formation of the C-C bond between two acetone molecules. The rate expression for isobutene formation predicts a second order dependence in acetone partial pressure at low partial pressures and a decrease in order with increasing acetone partial pressure, in good agreement with experimental observation. The apparent activation energy for isobutene formation from acetone over Hf/SiO2 is 116.3 kJ/mol, while that for Hf/Silicalite-1 is 79.5 kJ/mol. The lower activation energy for Hf/Silicalite-1 is attributed to enhanced adsorption of acetone and formation of a C-C bond favored by the H-bonding interaction between Hf-OH and an adjacent Si-OH group.

An unknown impurity was detected in olmesartan medoxomil active pharmaceutical ingredient (API), which was determined as 2-methyl-4-oxopentan-2-yl-protected olmesartan medoxomil by NMR and mass spe...

This study deals with the synthesis of catalytic samples containing MgO and 10, 15 and 25 wt% of CeO2 by co-precipitation method for aldol condensation of acetone. The obtained powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, temperature programmed desorption of CO2, X-ray photoelectron spectroscopy, nitrogen physisorption, and atomic force microscopy. The materials exhibited XRD patterns corresponding with cubic MgO and fluorite phase of ceria, medium and weak strength basic sites, characteristic electronic properties and distinctive trends regarding textural properties. The aldol condensation of acetone was carried out using the prepared catalyst samples; a decrease in acetone conversion as function of time-on-stream was noted for all catalyst, being the best performance exhibited by the sample containing 10 wt% ceria. The selectivity toward the different products of aldol condensation of acetone was dependent on catalytic sample, which was related to the unique properties of those solids. Diacetone alcohol was best produced by MgO-25 wt% ceria; for mesityl oxide yield, an increase in selectivity as time-on-stream was observed being the best material the sample MgO-10wt% ceria; whereas for phorone, the profiles indicate almost yield reduction as time-on-stream function, indicating the best performance the sample containing 15 wt% of CeO2. Isophorone was optimally produced by using pure MgO which was attributed to the presence of medium strength basic sites and adequate textural properties.

We report a systematic DRIFTS-MS study of surface acetone aldolization and self-deoxygenation reactions on ZrO2 and Zn1Zr10Oz, using temperature programmed surface reactions of both acetone reactant and possible intermediate compounds including diacetone alcohol, mesityl oxide, phorone, and isophorone. DRIFTS was used to monitor the evolution of surface species while MS was used to track corresponding gas phase products, in an attempt to identify the distinct reaction pathways observed on the two catalysts as well as the role zinc plays in the corresponding reaction pathways. It is found that aldol condensation (or aldolization) of acetone occurs readily at low temperature (298 K), forming mainly acetone dimers (i.e., diacetone alcohol, DAA/mesityl oxide, MSO) on both ZrO2 and Zn1Zr10Oz with the latter being more active. At elevated temperatures, secondary MSO reactions are diverted, mainly caused by the different Lewis basicity on the two catalysts. Over ZrO2, MSO reacts with activated acetone (acetone enolate) to form a surface 4,4-dimethyl-2,6-heptadione (phorone-C), which is further converted into a stable isophorone intermediate. At temperatures above 473 K, polymerization/oligomerization of isophorone along with basic hydroxyl promoted decomposition reactions occur, leading to the formation of heavier carbonaceous surface species and gas-phase side products (methane and CO2). The addition of zinc balances the surface acid-base properties on ZnxZryOz (i.e., Zn1Zr10Oz) via not only enhancing the surface Lewis basicity but passivating the strong acidity. This balance, especially the enhanced surface Lewis basicity largely promotes the α-H abstraction of MSO to form MSO enolate on the Zn1Zr10Oz, which thus favors the aldolization of MSO enolate and acetone, a reaction tends to form 2,6-dimethyl-2,5-heptadien-4-one (phorone-A). Phorone-A then readily decomposes to produce isobutene as a major product at temperature as low as 373 K. Note that, despite the facile formation of isobutene at low temperatures, a high temperature (673 K) is still necessary to release the strongly adsorbed formate/carbonate/acetate species via CO2 formation.

In this study, we discuss the development of a static headspace gas chromatography method for the analysis of residual acetone as well as its enriched impurities including mesityl oxide and diacetone alcohol, in a spray dried dispersion. The major challenges include the instability of mesityl oxide and diacetone alcohol at high temperature and peak tailing of diacetone alcohol. It was found that the headspace oven temperature has to be controlled to 150°C or below to prevent degradation beyond an acceptable level (< 1%). The peak tailing of diacetone alcohol was attributed to the "Phase Soaking" effect due to excessive diluent, which may condense and temporarily modify the stationary phase. The peak shape of diacetone alcohol is dependent on the column loading capacity and the peak area of N-methyl pyrrolidone, the solvent that elutes after diacetone alcohol. The headspace oven temperature was set at 140°C, where the highest response ratio of diacetone alcohol/N-methyl pyrrolidone at 1.46 and thus the best sensitivity was obtained. The calculated quantitation limits were 1 ppm for acetone, 3 ppm for mesityl oxide and 31 ppm for diacetone alcohol. The method successfully passed validation criteria for specificity, linearity, accuracy, and precision.

The synthesis of methyl isobutyl ketone (MIBK) can be carried out by the condensation of acetone in the presence of hydrogen over a supported metal catalyst. Previous studies have shown that hydroxyapatite is an excellent catalyst for condensation reactions. The present investigation was undertaken in order to elucidate the reaction mechanism and site requirements for acetone coupling to MIBK over a physical mixture of hydroxyapatite and Pd/SiO2. The reaction is found to proceed by consecutive aldol addition to form diacetone alcohol (DAA), dehydration of DAA to mesityl oxide (MO), and hydrogenation of MO to MIBK. The products formed by feeding DAA and MO reveal that aldol addition of acetone is rapid and reversible, and that the subsequent dehydration of DAA is rate-limiting. Pyridine and CO2 titration show that aldol dehydration occurs over basic sites via an E1cB mechanism. A series of cation-substituted hydroxyapatite samples were prepared by ion-exchange to further investigate the role of acid-base strength on catalyst performance. Characterization of these samples by PXRD, BET, ICP-OES, XPS, CO2-TPD, and Raman spectroscopy demonstrated that the exchange procedure used does not affect the bulk properties of hydroxyapatite. DFT calculations reveal that in addition to affecting the Lewis acidity/basicity of the support, the size of the cation plays a significant role in the chemistry: cations that are too large (Ba2+) or too small (Mg2+) adversely affect reaction rates due to excessive stabilization of intermediate species. Strontium-exchanged hydroxyapatite was found to be the most active catalyst because it promoted α-hydrogen abstraction and C O bond cleavage of DAA efficiently.

This paper presents investigation on the synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) as a result of the reaction of aniline and both acetone and mesityl oxide in the presence of selected sulfonic acid silica catalysts. Condensation of aniline with acetone is very complex process with the formation of significant number of side products, both desirable and undesirable considering the final product (TMQ). In acidic conditions and elevated reaction temperature the reactivity of main raw materials (aniline, acetone) is significantly high, what causes the formation of many side by-products lowering the selectivity of this reaction. In this paper the reaction of aniline with acetone in the presence of heterogeneous acidic silica catalysts were investigated in more detail and discussed. The results were confirmed by GC/MS analysis, that the presence of TMQ isomers and other by-products significantly affected the formation of final product. The formation of previously not described structural isomer of TMQ has been also demonstrated.

Efficient production of diacetone alcohol (DAA), mesityl oxide (MO) and isophorone (IP) is important for the high value utilization of acetone. For this, a novel process is proposed for the aldol condensation of acetone by refluxing on CaC2, whereby 95% of total selectivity of (DAA, MO and IP) and 85% of acetone conversion are achieved simultaneously under mild conditions (56 °C, 100 kPa). This result is superior to the previously reported ones, which may be ascribed to the extremely high catalytic capacity of CaC2 for the aldol condensation and instant separation of the target products from the catalyst to suppress the unwanted successive condensations. Moreover, the target products may be adjusted by operation conditions. Lower temperature and higher reflux rate favour the production of DAA and MO; MO and IP are favoured otherwise. The present process integrates several functions into one unit, i.e. the basic catalysis of calcium carbide, aldol condensation of acetone, instant distillation separation of the condensates, and the hydrolysis of CaC2 to C2H2, which makes it feasible to coproduce C2H2 and high value derivatives of acetone simultaneously.

A stepwise isopropylation reaction of acetone is developed for preparation of methyl isobutyl ketone (MIBK) through acetone condensation and a recoverable Pt/C-catalyzed transfer hydrogenation of mesityl oxide (MO) with isopropanol (IPA). Almost quantitative MO conversion (up to 99.9%) and excellent MIBK selectivity (up to 99.3%) could be achieved by the method. Since IPA can be obtained from propane, a cheap petrochemical product, the by-product acetone (AT) generated in the reduction of MO could be easily recovered and reused in the preparation of MO, and the Pt/C catalyst could be recycled and reused, this H2- and waste-free reaction may be a green and practical method for preparation of the useful fine chemical MIBK.

Acetone adsorption and catalytic interactions with a MgO nanoparticle surface was studied using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at room temperature. Acetone showed adsorption bands at 2965, 1717, 1597, 1422, 1415, 1367, 1238, 1229, and 1204 cm−1. The MgO was found to be a good catalyst for the activation of the aldol condensation reaction of acetone to form di-acetonealcohol (DAA). The OH group role on the MgO surface was found to be a suppression agent to the further dehydration of DAA to mesityl oxide. This is probably because the OH group blocks the active sites on the MgO surfaces that adsorbed the water formed from the dehydration of DAA. This conclusion was confirmed by identifying the basic site concentrations on MgO surface using DRIFTS and TPD studies of CO2 adsorption/desorption on MgO nanoparticles surface. The high-strength basic sites which are required to dehydrate DDA to mesityl oxide was found to represent only 17.5 % of the total basic site concentration, while the low-strength basic sites resulted from hydroxyl surface group represent 22.5 %. On the other hand, the acetone interaction with the MgO surfaces produced several components such as formaldehyde, acetate, ethoxide, as well as other carbonate species such as bicarbonate, bidentate carbonate, and monodentate carbonate. The results of the present investigation supply important essential insights into catalytic reactions resulted from acetone adsorption on MgO nanoparticle surfaces.

Amino acid and primary amine/amide co-catalyzed acetone condensation was investigated. It was found that l-proline had overwhelming catalytic activity over other amino acids as well as the analogues with similar structures. Surprisingly, thiourea, a very cheap and stable chemical, was found to be the favorable co-catalyst. Co-catalyzed by the recyclable l-proline and thiourea, condensation of acetone led to the useful products mesityl oxide (MO), diacetone alcohol (DAA) and isophorone (IP) in the excellent 96.3% total selectivity.

A polymer resin-supported proline catalyst was developed. The material might serve as an eco-friendly recoverable organocatalyst with industrial application potential. Its catalytic activity in acetone condensation was tested. Catalyst prepared under optimized conditions showed good performances, giving mesityl oxide (MO), diacetone alcohol (DAA) and isophorone (IP) in up to 87.7 % total selectivity, while the catalyst could be recovered with less than 5 % mass lost and could be reused for at least seven times without deactivation. Being able to convert market-excess acetone into useful bulk fine chemicals, the catalyst is of significant industrial value.

Mesoporous MgO micro-particles (20–80 μm) with crystalline phase framework wall were synthesized through a simple hydrothermal homogeneous precipitation route using urea as precipitating reagent. It possesses high specific area (278 m 2 /g), pseudo parallel pore and wall arrangement and large amount of basic sites and exhibits excellent catalytic activity for acetone condensation to mesityl oxide and isophorone even at low temperatures (

Aldol condensation of acetone was studied over solid base CaO—SnO2 catalyst in the 300—450 °C temperature range and at 15—75 atm pressure in a fixed-bed reactor. The main products are mesityl oxide and isophorone. The high stability of CaO—SnO2 catalyst performance was observed at pressure of 75 atm giving the acetone conversion of 36—41%. Increase in the temperature and pressure led to a simultaneous raise in acetone conversion. The maximum conversion of 41% was achieved at 400 °C, 75 atm and a flow rate of acetone of 8.1 g h–1 (g catalyst)–1.

Cyclotrimerization of biomass-based alkyl methyl ketones exhibits great potential as a route to biomass-derived aromatics by a sustainable valorization of biorefinery streams. In this study, acetone is used as a model reagent to screen solid acid catalysts for the aldol condensation reaction to the aromatic trimer mesitylene. From a broad catalyst screening promising activity is shown by the cation exchange resin Purolite CT275DR, the beta-zeolite H-BEA 35, and aluminosilicate Siralox 70/170 HPV which are used to further investigate reaction parameters. Acetone conversion and mesitylene yield increase with temperature and time, while yield of the intermediate mesityl oxide decreases. This effect is also found for higher quantities of catalyst acid sites and is accompanied with an increased side product formation which negatively affects total product selectivity. Analyzing the reaction progress shows a significant drop in catalyst productivity after an initial start-up phase. This observation is linked to a deactivation of the catalyst which involves water that is formed during the condensation reaction of acetone. Obtained results confirm the general viability of the aromatization of alkyl methyl ketones and can be considered the first step to an alternative sustainable route to biomass-derived aromatics compared to other currently discussed routes.

In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigate the adsorption and catalytic reaction of acetone on TiO2 surfaces. The adsorption of acetone has been investigated on hydrated (as-received from the provider) as well as dehydrated TiO2 nanoparticles. On both samples, acetone shows absorption bands results from the vibrational modes of acetone adsorbed molecules. The DRIFTS spectra indicate that acetone goes into a self-condensation reaction then it dehydrated yielding mesityl oxide. Formation of formaldehyde was observed only on as received sample and it was probably activated as a result to suppress mesityl oxide formation. This suppressed formation is a result of the existence of adsorbed H2O on the surface of as received TiO2. Adsorbed water is not favorable for aldolization/dehydration reaction because it can block the active sites for mesityl oxide formation. Outcomes of the current study provide fundamental insight into acetone adsorption and catalytic reaction on TiO2 nanoparticles. Specifically, this investigation demonstrates the adsorption mechanism of acetone on TiO2 surface and the role of presenting hydroxyl group on the TiO2 surface.

The effect of water on the hydrogenation of acetone to isopropanol (IPA) on the Ni/MgAlO catalyst was studied. It was found that small amount of water added in the acetone promoted the conversion of acetone to IPA, while more H2O added (>5%) significantly decreased the conversion of acetone. Microcalorimetric adsorption results showed that the presence of small amount of pre-adsorbed water (4% coverage) enhanced the adsorption of acetone while inhibited the adsorption of IPA on Ni, which might be the important reasons for the promotion effect of some water on the hydrogenation of acetone to IPA. On the other hand, the heats for the adsorption of H2, acetone and IPA on the Ni/MgAlO were significantly decreased when more water was pre-adsorbed, which might explain the inhibition effect of more water on the hydrogenation of acetone. The results of infrared spectroscopy revealed that the presence of water suppressed the dehydrogenation of adsorbed IPA to acetone and the formation of enolate and mesityl oxide species from adsorbed acetone, which might be the other reasons for the positive effect of water on the hydrogenation of acetone to IPA.

Currently, the well-established applications of nanomaterial-based cataluminescence (CTL) included the development of gas sensors for measuring a variety of volatile organic reactants and the rapid screening of nanocatalysts. There is obviously no good reason to disregard the identification of reaction products using nanomaterial-based CTL probes. In this work, we discovered the interesting connections between CTL signals and the contents of mesityl oxide, which is one of the important reaction products in the layered double hydroxide (LDH)-catalyzed acetone aldol condensation. Therefore, we have successfully developed a novel approach for rapid analysis of mesityl oxide using a LDH-assisted CTL probe. Mesityl oxide could be assayed in the range of 1.0–50 mM, and the detection limit for mesityl oxide (S/N = 3) was 0.5 mM. The developed CTL probe exhibited some advantages, such as simple configuration, fast response, and easy operation. The effectiveness and reliability of this approach for identifying mesityl oxide were further confirmed by comparing with a commercially available gas chromatography/mass spectrometry method. We believe that this strategy would stimulate the future development of the identification of reaction products in a variety of organic reactions by tuning CTL probe molecules.

Unexpectedly, L-proline/piperidine was found to be a better recyclable catalyst system than L-proline or piperidine alone in the condensation of acetone to prepare mesityl oxide (MO), an important intermediate in the chemical industry. Binding the catalyst system onto polymer resin enhanced the MO selectivity and reduced the catalyst loss. The mechanism of the bi-component catalyst system was also studied through control reactions, as well as by dynamic calculations. The MO selectivity could reach 74.4% and its isolated yield could reach 73.9%, based on the consumed acetone. Although the result does not immediately meet the requirement of industrial production, this study provides a novel organocatalyst system, which might offer a potential alternative to traditional inorganic catalysts that can be used under mild and neutral conditions.

PubMed: 28088865, Protein precipitation in acetone is frequently employed ahead of mass spectrometry for sample preconcentration and purification. Unfortunately, acetone is not chemically inert; mass artifacts have previously been observed on glycine-containing peptides when exposed to acetone under acidic conditions. We herein report a distinct chemical modification occurring at the level of intact proteins when incubated in acetone. This artifact manifests as one or more satellite peaks in the MS spectrum of intact protein, spaced 98 u above the mass of the unmodified protein. Other artifacts (+84, +112 u) also appear upon incubation of proteins or peptides in acetone. The reaction is pH-sensitive, being suppressed when proteins are exposed to acetone under acidic conditions. The +98 u artifact is speculated to originate through an intermediate product of aldol condensation of acetone to form diacetone alcohol and mesityl oxide. A +98 u product could originate from nucleophilic attack on mesityl oxide or through condensation with diacetone alcohol. Given the extent of modification possible upon exposure of proteins to acetone, particularly following overnight solvent exposure or incubation at room temperature, an awareness of the variables influencing this novel modification is valued by proteomics researchers who employ acetone precipitation for protein purification.

Acetone transformations on ZnO powder encompass a number of practical implications for heterogeneous catalysis, and the interest towards this system has fueled a substantial debate over the nature of the adsorbed molecule and its possible self-reactions. This work combines vibrational analysis and computational density functional theory investigation to reconcile some of the disagreements posed by the previous studies spanning wide range of experimental conditions and a variety of ZnO surfaces. The formation of rehybridized and non-rehybridized enolate species following acetone adsorption is analyzed by varying the molecular coverage in computational investigation using cluster models representing ZnO surfaces, and the resulting vibrational spectra are compared with the experimental measurements. In addition, self-aldol-condensation is explored to offer possible surface-catalyzed reaction pathways. Aldol condensation of acetone results in a stable species – enolized diacetone alcohol. Further transformation of this species into mesityl oxide is found to have a very high kinetic barrier.

We propose in this manuscript a new peroxo-mediated procedure for preparing magnesia-zirconia mixed oxides, with Mg/Zr molar ratio between 1 and 3, with enhanced distribution of basic sites. The mixed magnesia-zirconia oxides have been prepared from the gelled complex by Pechini-type method. The MgO-ZrO 2 materials have been characterized and used as catalysts for acetone aldol condensation. The proposed preparation method provides a high degree of molecular homogeneity and favours the formation of magnesia-stabilized zirconia phase. Acetone gas-phase self-condensation was carried out over these catalysts as model reaction requiring the presence of basic sites. The condensation yields diacetone alcohol and mesityl oxide as mean C6 products, and phorones, isophorones and mesitylene as C9 products. In comparison to Mg-Zr oxide prepared by co-precipitation, these new materials present better conversions and higher selectivity to linear dimers and trimers (as mesitylene), whereas the selectivity for isophorones is significantly lower. © 2014 Elsevier B.V., This work was supported by the Spanish Government (contract CTQ2011-29272-C04-02).

The most common method to determine the EOF in CE is to measure the migration time for a neutral marker. In this study, 12 compounds (three novel and some previously used) were investigated as EOF markers in aqueous and nonaqueous BGEs. In the aqueous buffer systems (ammonium acetate, sodium phosphate, and sodium borate) the evaluation included a wide pH range (2-12). Two BGEs contained chiral selectors (sulphated-β-CD, (-)-diketogulonic acid) and one that contained a micellar agent (SDS) were included in the study. The majority of the evaluated compounds were found to migrate with the EOF in the water-based BGEs and are thus useful as EOF markers. However, in the SDS-based BGE only four of the compounds (acetone, acrylamide, DMSO, and ethanol) were found to be applicable. In the nonaqueous BGEs 11 markers (acetone, acetophenone, acrylamide, anthracene, benzene, 4-(4-methoxybenzylamino)-7-nitro-2,1,3-benzoxadiazole, benzyl alcohol, 2,5-diphenyloxazole, ethanol, flavone, and mesityl oxide) seemed to be functional as EOF markers. Even though several of the evaluated compounds can be used as EOF markers in the investigated BGEs, the authors would recommend the use of acrylamide as a general marker for UV detection. Furthermore, the four fluorescent markers (of which three were novel) gave RSD values equal to the other markers and can be used for the determination of the EOF in CE or microchip CE with fluorescence detection.

Acetone gas phase aldol condensation over bulk and carbon-supported Mg–Zr has been studied in this work. The condensation yields C6 (mainly mesityl oxide) and C9 (phorones, isophorones and mesitylene) compounds, depending on reaction temperature and distribution of acid and basic sites. The influence of the temperature (323–723 K) was studied, higher C9 selectivities being obtained at higher temperatures (close to 50%). The influence of the concentration and the distribution of basic and acid sites was analyzed by comparing the results obtained with the bulk Mg–Zr and with Mg–Zr supported on non-microporous carbonaceous materials: high surface area graphites (HSAG) and carbon nanofibers (CNF). In addition, two different preparation methods (dry impregnation and co-precipitation) were tested. The performance of the catalysts is related to the distribution of acid and basic sites. Acid–basic pairs are needed for the acetone condensation, weak acidity for dehydration and cyclation reactions, and the strongest basicity for the condensation of mesityl oxide.

The aldol condensation reaction over sulfated zirconia led to the production of diacetone alcohol, which was further dehydrated forming mesityl oxide. The sulfated zirconia was obtained from zirconium acetate ethane sulfonate as a single source precursor. Oxides were obtained by calcinations of the precursors at 550–650 °C, while the self-condensation reaction of acetone was carried out at 150 °C. The precursor and the produced oxides were characterized using various characterization techniques. The precursors were synthesized with different acetate to ethane sulfonate ratio, ranging from 1 to 3. The major products obtained from the condensation reaction over the resulted oxide were mesityl oxide, mesitylene isophorone, naphthalene, and pentamers. The selectivity of mesityl oxide was approximately 100 % at the initial time-on-stream.

A neutral marker of the EOF can gain a nonzero effective mobility because of its possible interaction with a charged complexing agent, such as a chiral selector in CE. We determined effective mobilities of four compounds often used as EOF markers (dimethyl sulfoxide, mesityl oxide, nitromethane, and thiourea) in the BGE-containing sulfated β-CD (60 g/L). All the compounds studied were measurably mobilized by their interaction with the selector. The highest effective mobility (-3.0·10(-9) m(2) s(-1) V(-1)) was observed for thiourea and the lowest (-1.5·10(-9) m(2) s(-1) V(-1)) for dimethyl sulfoxide and nitromethane. The mobilities were determined by a new two-detector pressure mobilization method (2d method), which we propose, and the results were confirmed by standard CE measurements. In the 2d method, one marker zone is situated in the BGE containing the charged selector, while the second marker zone is surrounded with a selector-free BGE, which prevents its complexation. The initial distance between the two marker zones equals the capillary length from the inlet to the first detector. After a brief voltage application, the final distance between the marker zones is determined based on known capillary length from the first to the second detector. The difference between these two distances determines the effective mobility.

Sorbent-TRACK is a new device developed to monitor adsorption and surface oxidation of pollutants under direct plasma exposure. It is based on direct transmitted Fourier Transformed Infrared (FTIR) spectroscopy. A pyrex reactor under controlled gas pressure and composition is inserted on the infrared beam of a commercially available Nicolet 5700 FTIR spectrometer. A substrate holder is located on the optical path of the infrared beam. A thin pellet of a dedicated catalyst (CeO2 in the present work) is inserted in a substrate holder and can be exposed to direct plasma treatment using a Dielectric Barrier Discharge. The time resolution of Sorbent-TRACK is limited by the time resolution of the Nicolet 5700 FTIR spectrometer and close to 30 s. The dynamic of the adsorption and plasma oxidation of acetone and isopropanol on CeO2 are studied and intermediates are monitored. Performances and sensitivity of Sorbent-TRACK are reported Adsorption and oxidation of acetone leads to production of adsorbed isobutene and acetic acid, where oxidation of isopropanol gives mainly to adsorbed acetone, mesityl oxide and acetate. An increase of the plasma power leads to an increase of the isopropanol and acetone oxidation rate and a related increase of the production of adsorbed intermediates.

Combined collision-induced dissociation mass spectrometry experiments with DFT and MP2 calculations were employed to elucidate the molecular structures and energetics of dissociation reactions of uranyl species containing acetone and diacetone alcohol ligands. It is shown that solutions containing diacetone alcohol ligands can produce species with more than five oxygen atoms available for coordination. Calculations confirm that complexes with up to four diacetone alcohol ligands can be energetically stable but that the effective number of atoms coordinating with uranium in the equatorial plane does not exceed five. Water elimination reactions of diacetone alcohol ligands are shown to have two coordination-dependent reaction channels, through formation of mesityl oxide ligands or formation of alkoxide and protonated mesityl oxide species. The present results provide an explanation for the implausible observation of "[UO(2)(ACO)(6,7,8)](2+)" in and observed water-elimination reactions from purportedly uranyl-acetone complexes (Rios, D.; Rutkowski, P. X.; Van Stipdonk, M. J.; Gibson, J. K. Inorg. Chem. 2011, 50, 4781).

The performance of a hydrotalcite-derived mixed oxide (Mg3AlOx) for the three different aldolization reactions, concerned with the valorisation of biomass derivatives, has been studied in this work. The studied reactions were acetone self-condensation, ethanol condensation for the synthesis of C4 chemicals, and the aldolization of aqueous mixtures of acetone and furfural. The gas phase condensation of acetone generates mesityl oxide (C6) and isophorones (C9) as main products, with high selectivities for mesityl oxide (up to 80%). Reaction of ethanol leads to butanol and 1,3-butadiene, although important amounts of undesired ethylene were found at the highest temperatures. Concerning to the liquid-phase condensation of furfural with acetone, C8 and C13 species were found as reaction products. The performance of the catalysts can be explained in terms of the distribution of acid and basic sites determined by NH3- and CO2-TPD, being needed medium strength basic sites (Mn+–O2− pairs) for the condensation reactions, whereas the presence of acid–base pairs are needed for alcohols dehydrogenation (previous step for the condensation when ethanol is used as reactant). The presence of acid sites also leads to lateral reactions, such as the dehydration of ethanol or the rearrangement of lineal phorones into cyclic compounds (isophorones) in the reaction of acetone.

In this paper, we have examined the activity and selectivity of catalysts for the one-step, gas phase production of methyl isobutyl ketone (MIBK) from acetone (propanone) over the temperature range 373−573 K. The catalysts used were an impregnated MgO/silica, a Pd-MgO/silica formed from coimpregnation of the nitrates, and a Pd supported on a 1% Mg doped silica, Pd/Mg-SiO2. Using MgO/silica, mesityl oxide (MO) was formed with 100% selectivity at 373 and 473 K. Addition of Pd gave 100% selectivity to MIBK at 373 K, albeit at low conversion. Pd-MgO/silica revealed a promotional effect of the MgO on the hydrogenation function of the Pd and a promotional effect of the Pd on the aldol condensation activity of the MgO. The Pd/Mg-SiO2 catalyst showed high selectivity but low conversion, as no promoting effect was observed.

ZnAlFe mixed oxides with high surface area were obtained by the calcination (723 K) of ZnAlFe layered double hydroxides (LDHs). The calcined materials proved as basic catalysts in the gas phase acetone condensation exhibited high activity and high selectivity towards the formation of mesityl oxide.

This work presents the preparation and characterization of three bifunctional catalysts consisting of palladium supported on H-[Ga]ZSM5 zeolite, with a Si/Ga atomic ratio of 16 and Pd contents of 0.09, 0.50 and 1.02 wt%. The lowest and highest Pd content solids, which were assessed by transmission electron microscopy (TEM), show dispersion of the supported phase of 90% and 73%, respectively. The XPS characterization studies of the catalysts allowed to detect the presence of framework, tetrahedral Ga species, Pd(0) aggregates and Pd(0) atomically dispersed. These solids were tested in the synthesis of methyl isobutyl ketone (MIBK) from acetone. The results confirm that the catalyst with 1.02 wt% Pd, shows an initial global activity about twice as higher as that of 0.09 wt%Pd/H-[Ga]ZSM5, and additionally the selectivity to MIBK of the former is four times higher. These results show that the catalyst with lower Pd content do not have a high number of active metallic sites to catalyze the hydrogenation of Mesityl oxide to MIBK, even though it showed an excellent dispersion, while the catalyst with 1.02 wt% Pd seems to be a catalyst with a proper balance of the acidic-hydrogenating functions.

Pd metal supported on Zn II –Cr III mixed oxide is an efficient bifunctional catalyst for the one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and H 2 in the gas and liquid phases. The reaction involves acid-catalysed condensation of acetone to mesityl oxide, followed by its hydrogenation to MIBK. Diisobutyl ketone (DIBK) is a useful byproduct in this process. Zn–Cr oxides (Zn/Cr = 20:1–1:30) are prepared by coprecipitation of Zn II and Cr III hydroxides. The texture and acid properties (i.e., the nature, density, and strength of acid sites) of Zn–Cr oxides, as well as the Pd dispersion in the catalysts, are thoroughly characterised. For both the continuous gas-phase process and the batch liquid-phase process, the preferred catalyst formulation is 0.3 wt% Pd on the amorphous Zn–Cr (1:1) oxide ( S BET = 132 m 2 / g ) having Lewis acid sites (1.2 mmol/g density) with an enthalpy of NH 3 adsorption of − 155 kJ / mol . Both processes produce MIBK with a selectivity of 70–78% and 90% MIBK + DIBK total selectivity at 38–40% acetone conversion. Evidence is provided that hydrogenation of mesityl oxide to MIBK is the rate-limiting step in the gas-phase process.

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.