Condensation Reaction Of Acetone Research Articles

UiO-66 metal-organic frameworks as aldol condensation catalyst: Impact of defects, solvent, functionality on the catalytic activity and selectivity

Defected and amine-loaded zirconium-based metal–organic frameworks (MOF) UiO-66(Zr) have been characterized and chemically assessed in a condensation reaction of acetone and 4-nitrobenzaldehyde. The present work focuses primarily on the production of the aldol adduct as the main product while minimizing the formation of the enone adduct as a side product. Four analogues with varying numbers of missing linkers in the hexanuclear secondary building units, from one to four out of a total of 12, were synthesized. Thorough characterization showed that an increased number of defects results in an enhanced acidity, a higher internal surface area, and an increased accessibility of coordinatively unsaturated Zr-sites. The catalytic performance assessment revealed that defects, to a certain extent, positively affect the selectivity towards the aldol adduct, i,e. the catalyst, which is missing 3 of the 12 linkers, exhibits the highest activity in a solvent-free environment with a turnover frequency (TOF) amounting to 8.03 10-3 s−1. This TOF value is approximately double of the catalyst with 1.4 defects, which exhibited a TOF of only 4.41 10-3 s−1. Excluding more than three linkers more likely leads to 'missing cluster defects' and causes a decrease in the reaction rate towards the aldol adduct. A reduction in overall catalytic activity was observed upon functionalization with amine groups (UiO-66-NH2). Functionalization with L-proline (UiO-66Lpr) resulted in a shift from an acid to a basic reaction mechanism which was reflected by an improved selectivity towards the aldol adduct while maintaining a reasonable overall activity level. The best performances were obtained working solvent-free or with hexane as a solvent, while polar/semi-polar solvents hindered the catalyst performance. An 18-hour stability test demonstrated the robustness of defected and functionalized UiO-66.

Structure and Catalytic Properties of Magnesium Stannate in the Acetone Condensation Reaction

Structure and Catalytic Properties of Magnesium Stannate in the Acetone Condensation Reaction

Acetone Factor in the Design of Cu4-, Cu6-, and Cu9-Based Cage Coppersilsesquioxanes: Synthesis, Structural Features, and Catalytic Functionalization of Alkanes

The present study describes a new feature in the self-assembly of cagelike copperphenylsilsesquioxanes: the strong influence of acetone solvates on cage structure formation. By this simple approach, a series of novel tetra-, hexa-, or nonacoppersilsesquioxanes were isolated and characterized. In addition, several new complexes of Cu4 or Cu6 nuclearity bearing additional nitrogen-based ligands (ethylenediamine, 2,2'-bipyridine, phenanthroline, bathophenanthroline, or neocuproine) were produced. Single-crystal X-ray diffraction studies established molecular architectures of all of the synthesized products. Several coppersilsesquioxanes represent a novel feature of cagelike metallasilsesquioxane (CLMS) in terms of molecular topology. A Cu4-silsesquioxane complex with ethylenediamine (En) ligands was isolated via the unprecedented self-assembly of a partly condensed framework of silsesquioxane ligands, followed by the formation of a sandwich-like cage. Two prismatic Cu6 complexes represent the different conformers─regular and elliptical hexagonal prisms, "cylinders", determined by the different orientations of the coordinated acetone ligands ("shape-switch effect"). A heterometallic Cu4Na4-sandwich-like derivative represents the first example of a metallasilsesquioxane complex with diacetone alcohol ligands formed in situ due to acetone condensation reaction. As a selected example, the compound [(Ph6Si6O11)2Cu4En2]·(acetone)2 was explored in homogeneous oxidation catalysis. It catalyzes the oxidation of alkanes to alkyl hydroperoxides with hydrogen peroxide and the oxidation of alcohols to ketones with tert-butyl hydroperoxide. Radical species take part in the oxidation of alkanes. Besides, [(Ph6Si6O11)2Cu4En2]·(acetone)2 catalyzes the mild oxidative functionalization of gaseous alkanes (ethane, propane, n-butane, and i-butane). Two different model reactions were investigated: (1) the oxidation of gaseous alkanes with hydrogen peroxide to give a mixture of oxygenates (alcohols, ketones, or aldehydes) and (2) the carboxylation of Cn gaseous alkanes with carbon monoxide, water, and potassium peroxodisulfate to give Cn+1 carboxylic acids (main products), along with the corresponding Cn oxygenates. For these reactions, the effects of acid promoter, reaction time, and substrate scope were explored. As expected for free-radical-type reactions, the alkane reactivity follows the trend C2H6 < C3H8 < n-C4H10 < i-C4H10. The highest total product yields were observed in the carboxylation of i-butane (up to 61% based on i-C4H10). The product yields and catalyst turnover numbers (TONs) are remarkable, given an inertness of gaseous alkanes and very mild reaction conditions applied (low pressures, 50-60 °C temperatures).

Aldol condensation reaction of acetone on MgO nanoparticles surface: An in-situ drift investigation

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.

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.

Biomass‐Derived Aromatics by Solid Acid‐Catalyzed Aldol Condensation of Alkyl Methyl Ketones

AbstractCyclotrimerization 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.

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Layered double hydroxides (LDH or HT) or their derived mixed oxides present marked acid-base properties useful in catalysis, but they lead to agglomerate inducing a weak accessibility to the active sites. In this study we report the preparation and characterization of HT/Graphene (HT/rGO) nanocomposites as active and selective basic catalysts for the acetone condensation reaction. The graphene high specific surface area and structural compatibility with the HT allowed increasing the number and accessibility of the active sites and activity of this later. Two series of HT/rGO nanocomposites with 0.5≤HT/rGO≤10 mass ratio were prepared by: i) direct HT coprecipitation in the presence of GO; ii) self-assembly of preformed HT with GO. The prepared HT/rGO nanocomposites were dried either in air at 80°C or freeze-dried. A series of characterizations showed the great influence of the preparation method and HT/rGO mass ratio on both the nanocomposite structure and catalytic activity. An optimum activity was observed for a HT/rGO=10 catalyst. Particularly, the highest catalytic activity was found in those nanocomposites obtained by coprecipitation and freeze dried (3 times more active than bulk HT) which can be connected to their structure with a better accessibility to the basic sites.

Mesoporous MgO: Synthesis, physico-chemical, and catalytic properties

Mesoporous MgO was obtained via the hydrothermal synthesis using both ionogenic and non-ionogenic surfactants as structure-directing templates. The materials prepared were characterized by SEM, BET-N2, XRD, and TG-DTA techniques. MgO particles are spherical 20-μm aggregates of primary oxide particles well shaped as rectangular parallelepipeds. Magnesium oxide samples have the specific surface area of 290–400 m2/g and pore sizes of 3.3–4.1 nm. Their mesoporous structure remained unchanged after calcination up to 350°C. Catalytic activity of mesoporous MgO was studied in acetone condensation reaction.

A novel highly ordered mesoporous carbon-based solid acid for synthesis of bisphenol-A

Effect of different catalysts on phenol–acetone condensation reaction.

Preparation and Property of Y-Mg-Al-Layered Double Oxides

Y-Mg-Al-layered double Oxides (Y-Mg-Al-LDO) were prepared by calcining Y3+-doped Mg-Al-layered hydrotalcites at 823 K for 8 h from co-precipitation method. The samples were detected by XRD and CO2-TPD. Micro-structure and essential regularity were disclosed. The acetone condensation reaction as a probe reaction was carried on fixed-bed micro-reactor at reactive temperature 673 K, reactive time 3 h and liquid hourly space velocity (LHSV) 6 h-1 over Y-Mg-Al-LDO. The catalyst evaluation results show that Y-Mg-Al-LDO possess high catalytic activity. The maximum value of acetone conversion reached 37.53%. The selectivity and single-pass-yield of isophorone were 55.66% and 20.89%, respectively.

Lipase-catalyzed kinetic resolution of 4-aryl- and 4-heteroarylbut-3-en-2-ols

Several 4-aryl- and 4-heteroarylbut-3-en-2-ones (2a-c, bearing 4-phenyl-, 4-(furan-2-yl)- and 4-(1-benzyl-1H-indol-3yl)-substituents, respectively) were prepared by condensation reaction of acetone with the corresponding aldehydes (1a-c). Reduction of the ketones (2a,b) with NaBH4 resulted in the formation of the corresponding racemic secondary alcohols (rac-3a,b). On the other hand, reduction of the ketone bearing indole moiety (2c) gave an unstable product. The lipase-catalyzed enantiomer selective acetylation of the alcohols (rac-3a,b) by vinyl acetate has been investigated with a crude lipase from submerged fermentation (SmF) of a thermophilic fungus, with several crude enzyme preparations from solid state fermentation (SSF) of selected mesophilic fungi and with several commercially available lipases. The commercial and SmF lipases and the majority of SSF preparations exhibited high but usual enantiomer selectivities and resulted in the formation of (R)-acetates ((R)-4a,b) according to the Kazlauskas' rule. Several SSF preparations, however, behaved as selective anti-Kazlauskas catalysts.

Trans-Dichlorobis[N-(3,5-difluorophenyl)isopropylideneamine]palladium(II)

The title compound, [PdCl2(C9H9F2N)2], was obtained from the condensation reaction of acetone with trans-dichloro­bis(3,5-difluoro­aniline)palladium(II) under crystallization conditions. The Pd atom lies on an inversion centre and shows a square-planar geometry. The mol­ecules are linked via non-classical C—H⋯Cl and C—H⋯F inter­actions.

Physicochemical Characterization and Catalytic Properties of Titania Gel Doped with Lithium and Rubidium

The effect on titania of doping with lithium and rubidium titania gels has been studied in samples prepared with titanium (IV) tetra-n-butoxide co-gelling with the alkaline metal precursors. Titania and doped titania were characterized by X-Ray diffraction, which showed that the catalysts were nanostructured. In samples calcined at 400°C, the crystallite size of the anatase phase was 17 and 14 nm, and 78 and 38 nm for samples calcined at 600°C, for Li/TiO2 and Rb/TiO2, respectively. The specific surface areas of doped samples (400°C) are lower in Li/TiO2 (90 m2/g) than in Rb/TiO2(125 m2/g). Evaluation of their basic properties has been carried out in the acetone condensation reaction. It was found that the activity strongly depended on the Li and Rb ionic radii.

Investigation of Acid−Base Properties of Catalysts Obtained from Layered Double Hydroxides

Well-crystallized layered double hydroxides (LDH) containing Mg2+ or Ni2+ as divalent cations and Al3+ as trivalent cations were obtained either by coprecipitation (cp) or with the sol−gel (sg) method. After calcination, mixed oxide structures were achieved, as shown by XRD. Their acid−base properties were investigated through CO2 and NH3 TPD experiments and FT-IR spectroscopy, using CO2 and NH3 as probe molecules. Basic and acidic sites of medium-high strength were simultaneously revealed: the basic sites were mainly O2- atoms and Mn+−O2- pairs, while the Lewis acid sites were provided mainly by Al3+ in Mg-containing materials and by Al3+ and Ni2+ in Ni-containing materials. Several parameters, such as the nature of cations and anions involved in the LDH structure, the M2+/M3+ ratio, the synthesis method, and the activation conditions, influenced the acid−base properties of the mixed oxides. In particular, (i) Mg-containing samples showed higher basicity than Ni-containing samples, (ii) sg materials were more basic than the cp materials due to different textural and morphological features, (iii) the surface basicity increased with the calcination temperature up to 723−773 K while it markedly decreased after calcination at 873−923 K due to the surface enrichment in Al3+, and (iv) mixed oxides obtained from carbonate-exchanged LDHs showed the highest basicity while those containing chlorine showed predominantly acidic character. Except for the inactive structures containing high amounts of chlorine impurities, the OH--intercalated structures of the meixnerite type, obtained by the rehydration of mixed oxides under appropriate conditions, showed high activity and selectivity in the acetone condensation reaction. The Lewis-type basicity of the mixed oxides correlated well with the Bronsted-type basicity of the meixnerite-like LDHs, responsible for their remarkable selectivity toward the formation of diacetone alcohol.

Poisoning of aldol condensation reaction with H2O on acid catalysts

The effect of chemisorbing water on three catalysts previously evaluated in the acetone condensation reaction has been studied. The active sites in that reaction are Lewis acid sites present either on the surface of alumina or of nonframework alumina in zeolites. These sites are poisoned by water and the reaction rate decreases at the pace of the loss of Lewis sites. The stoichiometry of the poisoning reactions is one water molecule per site on alumina and two water molecules per site on nonframework alumina.

Acetone Condensation Reaction on Acid Catalysts

The condensation reaction of acetone on alumina and acid zeolites has been followed by FTIR. Under identical conditions, the reaction rate is faster on alumina, and the condensation goes beyond the formation of mesityl oxide. Zeolites without nonframework aluminum are poor catalysts. On HZSM-5 the reaction is about two orders of magnitude slower than on USY at 105°C. From these data, it appears that Lewis sites, even if they bound acetone less energetically than Brønsted sites, are responsible for the activation of the molecule. On alumina, the reaction would take place between gas phase acetone and acetone adsorbed on Lewis sites. On zeolites with nonframework aluminum and, thus, with Lewis sites, the reaction would involve acetone molecules adsorbed on Brønsted and Lewis sites, the activation occurring on the Lewis site.

Textural Properties and Catalytic Activity of Hydrotalcites

Double-layered hydroxides with hydrotalcite structure were synthesized with Mg/Al atomic ratios of 2.5 and 3 and with different contents of exchangeable Cl− and CO2−3anions. The basicity of these solids depends on several structural parameters and on the activation temperature. Microcalorimetric measurements, IR spectroscopy using a probe molecule, and a catalytic test reaction were carried out to characterize the basic sites. The structural evolution of the hydrotalcite upon exchange of Cl− for CO2−3 and calcination temperature shows a transformation with simultaneous removal of CO2 and water without phase segregation up to 673 K. The mixed oxide formed later could reversibly lead to the layered structure upon rehydration and carbonation. This process was studied by microcalorimetry and IR spectroscopy. The adsorption isotherm of CO2 shows an increase of the uptake and consequently of the basicity with initial CO2−3 content and calcination temperature up to 800 K. IR spectroscopy shows that the carbonation of the mixed oxide is essentially superficial and that the hydrotalcite structure may be restored upon H2O addition and 373-K treatment. Two types of Lewis acid sites related to a linear coordination of CO2 with Mg2+ and Al3+ cations are assigned. The appearance of a bicarbonate species implies that the basic sites are essentially OH groups. Moreover, a small number of strong basic sites, adsorbing CO2 with 140 kJ/mol, probably correspond to O2− centers. Hammett correlation in the condensation reaction of acetone and different substituted benzaldehydes shows analogies between hydrotalcite catalysis and the homogeneous basic reaction. The activities increase with CO2−3 content, calcination temperature, and Mg/Al ratio of the hydrotalcites. The basic strength of hydrotalcites is comparable to that of piperidine in homogeneous catalysis.

Kinetics by thermometry: an aldol condensation reaction

The principles of ‘thermokinetic’ experiments have been described, whereby the initial rates of chemical reaction in solution are determined by following the temperature rise in an adiabatic system; data are obtained within the first few seconds of mixing, and at rates of the order of one measurement s–1. The procedure has been applied to the base-catalysed condensation reaction of acetone to form diacetone alcohol, an exceptionally difficult reaction to follow because of the small extent to which the reaction proceeds. At 26 °C, the equilibrium constant for the base-catalysed ionisation of acetone has been established as having a value of 1.2(9) l mol–1 while the rate constant for the ionic dimerisation has the value 2.5(2)× 10–3 mol l–1 s–1.

Application of Pervaporation to Phenol–Acetone Condensation Reaction

Abstract Pervaporation through asymmetric polyimide membranes promoted phenol–acetone condensation catalyzed by cation exchange resin as a result of removal of produced water acting as a catalyst inhibitor. This resulted in a significant improvement of the reaction process.