Condensation Of Acetone Research Articles

Mechanism and Kinetics of Acetone Conversion to Isobutene over Isolated Hf Sites Grafted to Silicalite-1 and SiO2.

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.

The long-term performance of reconstructed MgAl hydrotalcite in the aldol condensation of furfural and acetone

The scale-up procedure of the acetone-furfural aldol condensation was studied on Mg-Al mixed oxide (molar ratio of 3:1). The catalyst’s stability was evaluated in three consecutive condensation steps at 60–70 °C, WHSV = 1.6–2/h-1 and the acetone-furfural molar ratio of 5:1 (mol:mol). After each condensation step, the catalyst’s reactivation was performed at 450 °C, ambient pressure under 50 NL/h nitrogen flow for 4 h. The experiments showed that catalyst deactivation was an effect related to the amount of treated feedstock. Moreover, our results showed the possibility of deactivation compensation by increasing reaction temperature or decreasing feeding rate. From a reaction mechanism point of view, furfural reacted first with acetone to FAc (4-(2-furyl)-3-buten-2-one), a crucial compound for heavier compounds formation.

Elucidation of Active Sites in Aldol Condensation of Acetone over Single-Facet Dominant Anatase TiO2 (101) and (001) Catalysts.

Aldol condensations of carbonyl compounds for C–C bond formation are a very important class of reactions in organic synthesis and upgrading of biomass-derived feedstocks. However, the atomic level understanding of reaction mechanisms and structure–activity correlation on widely used transition metal oxide catalysts are limited due to the high degree of structural heterogeneity of catalysts such as commercial TiO2 powders. Here, we provide a deep understanding of the reaction mechanisms, kinetics, and structure–function relationships for vapor phase acetone aldol condensation through the controlled synthesis of two catalysts with high surface areas and clean, dominant facets, coupled with detailed characterization and kinetic studies that are further assisted by density functional theory (DFT) calculations. Temperature-dependent diffuse reflectance infrared Fourier transform spectroscopy showed the existence of abundant acetone bonded to surface hydroxyl groups (acetone-OsH) and acetone bonded to Lewis acid sites (acetone-Ti5c) on the surface of both {101} and {001} facet dominant TiO2. Intermolecular C–C coupling of theenolate intermediate from acetone-Ti5c and a vicinal acetone-OsH is a kinetically relevant step, which is consistent with kinetic and isotopic studies as well as DFT calculations. The {001} facet showed a lower apparent activation energy (or higher activity) than the {101} facet. This is likely caused by the weaker Lewis acid and Brønsted base strengths of the {001} facet which favors the reprotonation–desorption of the coupled intermediate, making the C–C coupling step more exothermic on the {001} facet and resulting in an earlier transition state with a lower activation barrier. It is also possible that the {001} facet has a smoother surface configuration and less steric hindrance during intermolecular C–C bond formation than the {101} facet.

Study of the Aniline and Acetone Condensation Reaction under Electrospray Ionization Conditions

The present paper deals with the study of condensation reaction of aniline with acetone under electrospray ionization (ESI) conditions . An experimental setup is described for conducting reactions under ESI conditions with a possibility of the accumulation of reaction products. The aniline and acetone condensation products were analyzed by gas chromatography–mass spectrometry. Spraying this mixture with high concentration of formic acid, results in the formation of N-phenylformamide, N,N'-diphenylmethaneimidamide, and 1,2-dihydro-2,2,4-trimethylquinoline; the last one is the only product of the reaction of aniline with acetone. Thus, the Schiff base formation reaction radically changes its direction. The results obtained using the proposed experimental setup open up new prospects both for studying chemical reactions in charged microdroplets and for the use of ESI as a preparative method for the synthesis of organic compounds.

Microwave-assisted condensation of bio-based hydroxymethylfurfural and acetone over recyclable hydrotalcite-related materials

The microwave-assisted neat aldol condensation of biomass-derived platform chemical 5-hydroxymethyl furfural (HMF) and acetone over hydrotalcite-based catalysts has been studied. High conversions are obtained in very short times with relatively low catalyst loadings. The condensation products, which are biofuel and functional polymer precursors, are selectively obtained. Heterogeneous catalysts with different basic properties derived from the same parent hydrotalcite have been tested. The solids were characterized by PXRD, ICP-AES, ESEM-EDX, TEM, FT-IR and Raman spectroscopy, N2 physisorption, CO2 chemisorption and TGA-MS. The products in the final reaction mixtures were determined by GC-FID and -MS, HPLC-DAD and -TOF, and NMR. NMR was also used to determine the stereoconfiguration of the obtained products and pointed to a complete E-selectivity of our process. Different catalyst recycle strategies have been explored, and the most active catalyst, a meixnerite-type solid, can be recycled with low activity loss.

Microwave-Assisted Aldol Condensation of Furfural and Acetone over Mg–Al Hydrotalcite-Based Catalysts

The depletion of fossil fuel resources has prompted the scientific community to find renewable alternatives for the production of energy and chemicals. The products of the aldol condensation between bio-based furfural and acetone have been individuated as promising intermediates for the preparation of biofuels and polymeric materials. We developed a protocol for the microwave-assisted condensation of these two compounds over hydrotalcite-based materials. Mg:Al 2:1 hydrotalcite was prepared by co-precipitation; the obtained solid was calcined to afford the corresponding mixed metal oxide, which was then rehydrated to obtain a meixnerite-type material. The prepared solids were characterized by PXRD, ICP-AES, TGA-DSC and N2 physisorption, and tested as catalysts in the aldol condensation of acetone and furfural in a microwave reactor. The performance of the catalysts was assessed and compared; the meixnerite catalyst proved to be the most active, followed by the mixed metal oxide and the as-synthesized hydrotalcite, which has often been reported to be inactive. In all cases, the reaction is quite fast and selective, which makes our protocol useful for rapidly converting furfural and acetone into their condensation products.

Synthesis of MgO and MgO–CeO2 by co-precipitation for the catalytic conversion of acetone by aldol condensation

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.

New insight into the phase transformation of sepiolite upon alkali activation: Impact on composition, structure, texture, and catalytic/sorptive properties

Wet NaOH activation of natural sepiolite was studied for the purpose of endowing the material with enhanced basicity for potential catalytic/sorptive applications. A series of synthesized solids were characterized with X-ray powder diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), N2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and 29Si magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). Surface basicity was determined by titration with benzoic acid. The study led to the major reinterpretation of the existing knowledge on the sepiolite phase transformation to its sodium form (loughlinite). Activation with NaOH involved significant desilication of sepiolite, while the loss of Mg from the solid was prevented due to the intracrystalline preciptation of amorphous Mg(OH)2. Formation of Mg(OH)2 affected the material composition, hindered the access of nitrogen molecules to the micropore system, and enhanced the product basicity. For the first time the Si sites at the centre of structural ribbons were identified as part of the silicate framework most susceptible to leaching upon alkaline treatment. Although the NaOH treated product had the structure of loughlinite, it was in fact a composite of desilicated loughlinite and amorphous Mg(OH)2. The materials were tested as catalysts in aldol self condensation of acetone and oxidation of cyclohexanone to ε-caprolactone, and as CO2 sorbents.

Nickel(II) Phosphane‐ and N‐heterocyclic Carbene Complexes with Tridentate, Dianionic [S,N,O]2– Ligands

Square‐planar dinuclear nickel(II) complexes containing [S,N,O]2– ligands formed by condensation of acetyl acetone or benzoyl acetone with cysteamine were prepared. These dimeric nickel(II) compounds undergo bridge‐cleavage reactions with the cage phosphine PTA (PTA = 1,3,5‐triaza‐7‐phosphaadamantane) or in situ generated N‐heterocyclic carbenes. The resulting diamagnetic, square planar NiII complexes were characterized by spectroscopic methods and X‐ray diffraction.

Synthesis <i>N</i>-Phenyl Pyrazoline from Dibenzalacetone and Heme Polymeration Inhibitory Activity (HPIA) Assay

The synthesis of 1,5-diphenyl-3-styryl-4,5-dihydro-1H-pyrazole (B1) and 5-(3,4-dimethoxyphenyl)-3-(3,4-dimethoxystyryl)-1-phenyl-4,5-dihydro-1H-pyrazole (B2) have been conducted from 1,5-diphenylpenta-1,4-dien-3-on (A1) and 1,5-bis(3,4-dimethoxyphenyl)penta-1,4-dien-3-one (A2). Heme polymerization inhibitory activity (HPIA) assay of the synthesized compounds has also been carried out. The first step of reaction was Claisen-Schmidt condensation of benzaldehyde derivatives and acetone using NaOH 20% and ethanol as solvent. Dibenzalacetone derivatives were reacted with phenylhydrazine using acetic acid to form N-phenylpyrazoline. The structure of products was characterized by FT-IR, GC-MS, DI-MS, 1H- and 13C-NMR The result of heme polymerization inhibitory activity assay showed that IC50 of B1 and B2 1.26 and 0.79 mM while quinine 1.26 mM. The result indicated that compound B2 was more potent as antimalarial than quinine.

On the influence of acidic admixtures in furfural on the performance of MgAl mixed oxide catalysts in aldol condensation of furfural and acetone

Aldol condensation of furfural and acetone is often used as a model reaction to test acid-base properties of solid catalysts. The present study describes the effect of furfural acidity on the catalytic performance of MgAl mixed oxides. Three furfural sources differing in their acidity were used and compared in aldol condensation at T = 55 °C and acetone to furfural molar ratio of 10. The furfural conversion over MgAl mixed oxides depended on the acidity of the furfural source, and the catalysts were partially consumed for neutralization of acid admixtures present in furfural. Only for some furfurals could the furfural conversion be improved by distilling the as-received furfural prior to the aldol condensation experiments. Moreover, the storage of the freshly distilled furfural during a few days, even in a closed flask and at a dark place, resulted in a substantial decrease in furfural conversion in aldol condensation. The results indicate that the distillation of the as-received furfural is an effective method to control the performance of basic catalysts at comparable reaction conditions only for some furfurals. Furthermore, the storage of the freshly distilled furfural has to be performed with care to avoid its re-oxidation.

Aqueous Phase Aldol Condensation of Formaldehyde and Acetone on Anatase TiO2(101) Surface: A Theoretical Investigation

AbstractA mechanistic understanding of catalytic reactions at solid‐liquid interface is limited both experimentally and theoretically but attracts much interest. Using density functional theory calculations (DFT) and ab initio molecular dynamics (AIMD) simulations, we investigated the effect of liquid water on α‐H abstraction, C−C coupling, and dehydration steps of aldol condensation of formaldehyde and acetone on an anatase TiO2(101) surface. The existence of the aqueous phase lowered the Gibbs energy of activation of dehydration step pronouncedly from 187 to 74 kJ/mol through proton transfer mechanism, making the hydrogenation pathway more favorable in the aqueous phase. In contrast, a mixed route prevails in the vapor phase. This work provides insights into the effect of the bulk water through a proton transfer mechanism on the dehydrogenation, C−C coupling, and dehydration steps.

Upgrading of Biomass-Derived Feedstocks to Liquid Transportation Fuel Precursors by Aldol Condensation

The upgrading of biomass-derived feedstocks to liquid transportation fuels is complex because of the chemical differences between biomass-derived chemicals and conventional fuels. Aldol condensation may play an important role in converting biomass-derive components to fuels because it allows smaller species to be converted to larger species that are more similar to conventional fuels. This review covers recent progress in aldol condensation of biomass-derived 5-hydroxymethylfurfural, acetone, methyl ketones, acetoin, levulinic acid, furfural, cyclopentanone and levulinic acid. The corresponding catalytic mechanisms and future research directions in these areas are also discussed.

Synthesis of jet fuel range high-density dicycloalkanes with methyl benzaldehyde and acetone

High-density dicycloalkanes were first produced by the acid-catalyzed aldol condensation of acetone and methyl benzaldehyde over protonated titanate nanotubes followed by hydrodeoxygenation in cyclohexane.

Effect of catalyst morphology and hydrogen co-feeding on the acid-catalysed transformation of acetone into mesitylene

Surface chemistry and pore topology affect mesitylene selectivity in acid-catalysed acetone condensation. Hydrogen improves both catalyst stability and condensation selectivity.

DIETHYL OXALATE AND ACETONE REACTION WITH SUBSEQUENT INTERACTION WITH SUBSTITUTED 7-AMINOINDOLES

The study described in the article is a continuation of scientific research on the problem of finding convenient methods for the synthesis of nitrogen-containing heterocyclic compounds with biological activity. This article describes the synthesis of tricyclic nitrogen-containing substances based on the interaction of oxalic acid, acetone and sodium diethyl ether with subsequent introduction of 2,3-dimethyl- or 1,2,3-trimethyl-7-aminoindoles into the reaction system in the presence of acetic acid. The synthesis is carried out in two stages. Both stages are carried out under one-reactor synthesis conditions, where toluene is used as a solvent. So by condensation of acetone with diethyloxalate in the presence of sodium, followed by the action of 1,2,3-trimethyl-7-aminoindole in acetic acid, previously unknown ethyl ester (2Z)-4-oxo-2-[(1,2), 3-trimethyl-1H-indole-7-yl)amino]-2-pentanoic acid with a yield of 28%. Subsequently, the synthesized compound was subjected to acid cyclization (boiling in trifluoroacetic acid, 72 °С), as a result of which 1,2,3,6-tetramethyl-1H-pyrrolo[3,2-h]quinoline-8-carboxylic acid ethyl ester was obtained with a yield of 36%. In the case of the use of 2,3-dimethyl-7-aminoindole, unsubstituted in the first position, (2Z)-5,6-dimethyl-2-(2-oxopropylidene)-1,2-dihydro-3-pyrrolо[1,2,3-de]quinoxalin-3-one with a yield of 37%. Monitoring the progress of the reaction and the purity of the obtained compounds was carried out chromatographically. The structural features of the synthesized compounds were established using UV spectroscopy and 1H NMR spectrometry. In the experimental 1H NMR spectra, the signals of the proton-containing groups of ethyl esters of indolyl carboxylic and pyrroloquinoline of carboxylic acids, as well as pyr-rolo[1,2,3-de]quinoxaline, with comparable integral intensity values are found in the expected region.

Dehydrocondensation of Acetone under Supercritical Conditions

Abstract—The condensation of acetone under supercritical conditions was studied at different temperatures, pressures, and densities in a static mode. The high yield of mesitylene under the given conditions and its easy isolation from the reaction mixture made it possible to propose a new method for its preparation.

Facile ultrasound-assisted grafting of silica gel by aminopropyltriethoxysilane for aldol condensation of furfural and acetone.

This work focuses on the development of a simple method to prepare heterogeneous catalysts with tunable basicity and stability for aldol condensation of furfural and acetone. Silica gel was grafted by aminopropyltriethoxysilane (APTES) with 20, 30, 40 and 50 wt. % of APTES using probe-type ultrasonicator with a power of 130 W and a frequency of 20 kHz. The grafted samples were studied by XRD, SEM, N2 sorption, FTIR, XPS, CHN and TG analysis, and CO2-TPD. The sonication facilitated the bond formation between APTES and the silica gel with less pore blocking than the conventional grafting method. The basicity of the samples was tunable with the quantity of APTES loading. The grafted samples were active catalysts for aldol condensation between furfural and acetone at 60 °C. The catalyst with 30 wt. % APTES grafting (30APS-U) provided a nearly complete furfural conversion and high furfurylbutenone selectivity. The conversion and selectivity increased with time and reached the highest values at 24 h. Thus, the catalysts with tunable basicity prepared by ultrasound-assisted grafting of silica with various APTES amounts were effective in furfural valorization.

Rhenium(I) and (V) complexes of aroylhydrazone derivatives: Synthesis, spectroscopic and crystallographic studies

The coordination mode of aroylhydrazones-based ligands to the fac-[ReCO)3]+, [ReO]3+ and [Re2O3]4+ cores is reported. The reaction of di-2-pyridylketone-2-aminobenzoylhydrazone (Hdpa) with [ReCO5Cl] in ethanol led to the complex [Re(CO)3Cl(Hdpa)] (1). Similar reaction using N′((pyridin-2-yl)methylene)benzohydrazide (Hhpmb) and [ReCO5Br] led to the complex [Re(CO)3Br(Hhpmb)] (2). The reaction of 2-hydroxy-N′-((thiophen-3-yl)methylene)benzohydrazide (H2htmb) with trans-[ReOCl3(PPh3)2] in acetonitrile gave the complex cis-[ReOCl2(Hhtmb)(PPh3)] (3). The complexes cis-[ReOBr2(Hhpb)(PPh3)] (4) and (μ-O)[ReO(pbz)2]2 (5) were isolated from the reaction of [ReOBr3(PPh3)2] with salicylhydrazide (Hshz) and trans-[ReO2(py)4]Cl with benzohydrazide (Hbhz) in acetone respectively. The chelating ligands 2-hydroxy-N′-(propan-2-ylidene)benzohydrazide (H2hpb) and N′-(propan-2-ylidene)benzohydrazide (Hpbz) were formed from the condensation of acetone with Hshz and Hbhz respectively upon the reaction of [ReOBr3(PPh3)2] with Hshz in acetone and [ReO2(py)4]Cl with Hbhz in acetone respectively. In addition to the X-ray crystal structures, conductivity, infra-red, 1H NMR and electronic properties are reported.

Kinetics of acetone hydrogenation for synthesis of isopropyl alcohol over Cu-Al mixed oxide catalysts

Abstract Vapor phase hydrogenation of acetone was carried out over Cu-Al mixed oxide catalysts. The catalysts were synthesized via co-precipitation method with Cu:Al atomic ratio varied from 0.25 to 1. The characterization of the catalysts was done by using XRD, BET, FESEM (coupled with EDS), FTIR, H2-TPR, NH3-TPD and CO2-TPD. The performance of the synthesized catalysts was evaluated in a continuous packed bed reactor by varying parameters such as temperature (150 to 225 °C), H2/acetone mole ratio (0.5 to 1.25) and space-velocity (0.09 to 0.145 kmol acetone/kg cat. h). Along with direct hydrogenation, condensation of acetone also occurred due to the presence of basic and acidic sites in the catalysts. The catalyst having Cu:Al atomic ratio of 0.5 showed highest selectivity (98%) to isopropyl alcohol at 175 °C. Kinetic study was conducted at different temperatures by varying space-velocity. LHHW type model rate equations were fitted with the kinetic data obtained at three different temperatures. The activation energy of the reaction was determined to be 44.3 kJ/mol.