Yield Of Acetophenone Research Articles

Response Surface Methodology Optimization of Friedel–Crafts Acylation Using Phosphotungstic Acid Encapsulation in a Flexible Nanoporous Material

The present study aims at investigating the performance of Friedel–Crafts acylation of phenols and acyl chlorides over the PTA@MIL-53 (Fe) catalyst (phosphotungstic acid encapsulated in MIL-53 (Fe) via the one-pot method) under ultrasound irradiation. PTA@MIL-53 (Fe) was synthesized using ultrasound irradiation at ambient temperature and pressure. Moreover, X-ray diffraction, energy-dispersive X-ray, Fourier transform infrared, scanning electron microscopy, N2 physisorption, and inductively coupled plasma optical emission spectrometry characterization analyses were performed to characterize the prepared composite. The reactions took place under an ultrasonic environment at ambient temperature and pressure. The obtained results reveal that the synthesized catalyst is efficient in an ultrasound irradiation environment for Friedel–Crafts reactions. The regeneration experiments indicated no significant change in the catalyst performance even after being reused for five times. Furthermore, the response surface methodology was applied to find the relationships between some specific variables and para-hydroxy acetophenone yield as a response. Finally, the results were validated with the experimental data, with which the model results were in good agreement.

Fast and Selective Aqueous-Phase Oxidation of Styrene to Acetophenone Using a Mesoporous Janus-Type Palladium Catalyst.

A heterogeneous Janus-type palladium interphase catalyst was obtained by selective surface modification of a hollow mesoporous silica material. The catalyst comprises hydrophobic octyl groups on one side of the silica nanosheets and single-site bis-imidazoline dichlorido palladium(II) complexes on the other. The structure of this composite material has been analyzed by means of elemental analysis, atomic absorption spectroscopy, BET surface analysis, TGA, SEM and solid-state CP-MAS 13C and 29Si NMR spectroscopy. The catalyst showed extraordinary activity for the aqueous-phase oxidation of styrene to acetophenone using 30% hydrogen peroxide as the oxidant. An 88% yield of acetophenone could be achieved after 60 min.

Trace Single‐Atom Iron‐Decorated Nitrogen‐Doped Carbons Enable Highly Efficient Selective Oxidation of Ethyl Benzene

AbstractThe hybridization of abundant transition metals with facile nitrogen‐doped carbons is an effective strategy to fabricate advanced functional materials for targeted applications. Herein, we demonstrate a novel and straightforward synthetic approach of preparing a series of different transition metal‐modified nitrogen‐doped carbons (M/NC, M=Fe, Co, Ni) through the addition of corresponding metal sulfates during the polymerization of aniline, followed by high‐temperature (873–1273 K) pyrolysis treatment. While Fe/NC features predominantly single Fe atoms, nanoparticles of mixed metal oxides and or carbonates are formed on Co/NC and Ni/NC. When employed in the selective oxidation of ethyl benzene by using tert‐butyl hydroperoxide both as the solvent and the oxidant, these materials showed promoted catalytic response with the order of Fe>Co>Ni as compared with the metal‐free analogue. The performance can be further tuned by controlling the pyrolysis temperature, and the best performance can be achieved over Fe/NC‐1273 (0.153 wt.% Fe), affording an unprecedented acetophenone yield of 98 % and excellent cycling performance.

Palladium/graphitic carbon nitride catalyst for selective oxygen transfer in Wacker oxidation

Nanoscaled palladium particles supported on graphitic carbon nitride (Pd0/g-C3N4) is prepared to improve the oxygen transfer in Wacker oxidation via chemical reduction method. From the analysis of FT-IR, XRD, SEM, TEM, XPS and ICP, Pd0 particles are firmly combined with g-C3N4 layers, and sub-surface ones occupy most of the components. It is worth mentioning that graphene oxide (GO), which is completely recyclable without further pollution, can be used as a ‘solid weak acid’ taking the place of H2SO4 and CF3COOH. Under the optimization conditions, as many as 46 kinds of olefins are transferred into corresponding products with satisfactory yields, and o-methyl styrene gets the highest yield of 94%. After five times of recycling experiment, the yield of acetophenone only decreases by about 7.0% in the uniform reaction process. In virtue of former research results and molecular electrostatic potential, a possible mechanism is put forward to explain the catalytic process.

Oxidation of benzyl alcohols to ketones and aldehydes by O3 process enhanced using high-gravity technology

Abstract In this study, a practical process for ozonization of benzyl alcohols to ketones and aldehydes in a rotating packed bed (RPB-O3) reactor has been developed. Using 1-phenylethanol as a model reactant, the performance of RPB-O3 process in different solvents has been compared with the commonly used stirred tank reactor (STR-O3). Ethyl acetate was the optimum solvent for the conversion of 1-phenylenthanol to acetophenone in RPB-O3 process, with 78% yield after 30 min. In a parallel STR-O3 experiment, the yield of acetophenone was 50%. Other experimental variables, i.e. O3 concentration, reaction time, high-gravity factor and liquid flow rate were also optimized. The highest yield of acetophenone was obtained using O3 concentration of 80 mg·L−1, reaction time of 30 min, high gravity factor of 40 and liquid flow rate of 120 L·h−1. Under the optimized reaction conditions, a series of structurally diverse primary and secondary alcohols was oxidized with (19%–92%) yield. The ozonization mechanism was studied by Electron Paramagnetic Resonance (EPR) spectroscopy, monitoring the radical species formed upon self-decomposition of O3. The characteristic quadruple peak with the 1:2:2:1 intensity ratio that corresponds to hydroxyl radicals (·OH) was observed in the electron paramagnetic resonance (EPR) spectrum, indicating an indirect oxidation mechanism of alcohols via ·OH radical.

Solvent-free oxidation of 1-phenylethanol catalysed by gold nanoparticles supported on carbon powder materials

Gold (1 wt.%) was loaded on several carbon materials, namely, polymer based carbon xerogel, activated carbon, microdiamonds, nanodiamonds, graphite and silicon carbide by double impregnation and sol immobilisation. The obtained catalysts were characterised by N2 adsorption at -196 ºC, high-resolution transmission electron microscopy, high-angle annular dark-field imaging (Z-contrast), temperature programmed desorption, atomic absorption spectroscopy and X-ray photoelectron spectroscopy. The obtained materials were tested on the microwave-assisted solvent-free oxidation of 1-phenylethanol by tert-butyl hydroperoxide (TBHP) to produce acetophenone. The results showed that the catalytic activity was influenced by several factors, namely, the nature of the support, reaction time and temperature, amount of catalyst, presence of additives, among others. The best values for acetophenone yield (99.9%) were obtained with Au deposited on microdiamonds by the colloidal method. Catalyst recyclability was tested up to six consecutive cycles at the optimized conditions for each catalyst, and it was found that Au on microdiamonds, prepared by the colloidal method, also maintained higher activity after several reaction cycles as compared to the other carbon supports.

Au nanoparticles controlled by lattice Zn2+ of supports

Supported Au nanoparticles (NPs) have attracted much attention in catalytic field because of their high activity and selectivity. However, its activity was affected by its dispersion. In this work, a controlled impregnation method was used to prepare Au/Zn-hydrotalcites (Au/Zn-HTs). The role of lattice Zn2+ in controlling Au NPs was studied. The size, structure, and composition of Au NPs were characterized using techniques of nitrogen physisorption, X-ray diffraction, scanning transmission electron microscopy, temperature-programmed reduction, and X-ray photoelectron spectroscopy. The mean size of Au/Zn-HTs by this work was 1.8 nm, which was smaller than the mean size of catalysts by traditional method. The mechanism of forming Au NPs was investigated. There was electron transfer between Au and Zn2+, displaying the interaction between them. It was found that dispersion of Zn2+ and the interaction between Au and Zn were two key factors affecting the dispersion of Au NPs. The dispersion of Zn2+ could be controlled by adjusting its content in HTs. The yield of acetophenone was 92% by Au/Zn-HTs, while it was below 65% for catalysts prepared by traditional method.

Synthesis of Nitrogen-Doped Mesoporous Carbon for the Catalytic Oxidation of Ethylbenzene

Nitrogen-doped ordered mesoporous carbon (NOMC) was fabricated via a simple hard-template method by functionalized ionic liquids as carbon and nitrogen source, SBA-15 as a hard-template. The obtained NOMC materials have a high nitrogen content of 5.55 %, a high surface area of 446.2 m2 g-1, and an excellent performance in catalysing oxidation of ethylbenzene. The conversion rate of ethylbenzene can be up to 84.5% and the yield of acetophenone can be up to 69.9%, the results indicated that the NOMC materials have a faster catalytic rate and a higher production of acetophenone than catalyst-free and CMK-3, due to their uniform pore size, high surface area and rich active sites in the carbon pore walls.

Arylhydrazone Cd(II) and Cu(II) complexes as catalysts for secondary alcohol oxidation

Reaction of cadmium acetate hydrate with sodium 2-[2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl]terephthalate (Na2HL), in the presence of imidazole (im), leads to the polymeric species [Cd(im)3(µ,η-HL-1κOO′:2κO″O‴)]n (1) that is characterized by IR spectroscopy, elemental analysis, UV–Vis absorption spectroscopy and X-ray diffraction analysis. Complex 1 was successfully tested as catalyst for the peroxidative oxidation of alcohols (1-phenylethanol and cyclohexanol) to the corresponding ketones under microwave irradiation, with no added solvent and under mild conditions. The use of tert-butylhydroperoxide as oxidant, of TEMPO as additive, and a temperature of 80°C leads in 1h to a yield of acetophenone (from 1-phenylethanol) of nearly 70% or to a cyclohexanone yield (from cyclohexanol) of 66%. A comparison between the catalytic activity of 1 with those (also studied in this work) shown by Cu(II) complexes bearing the same or related hydrazo ligand is presented.

Effects of oxygen-containing substituents on pyrolysis characteristics of β-O-4 type model compounds

In order to uncover the influence of oxygen-containing functional groups on the pyrolysis characteristics of β-O-4 type model compounds, in-situ diffuse reflectance infrared pyrolysis and pyroprobe-GC–MS were used to study the migration patterns of functional groups and the specific pyrolysis product distributions with changing temperature. The results showed that the initial temperature of phenolic hydroxy production was 300°C, and peaks corresponding to this increased gradually in intensity in 1-benzyl-2-(2-methoxy-phenol)-ethanol, while this product did not begin appearing until 600°C in 1-ethyl-benzene-2-(2-methoxy-phenol). The intensities of the CH4 peaks were similar in all three samples, but the CO2 absorption peak was significantly lower in 1-(4-methoxy-phenoxy)-2-(2-methoxy-phenol)-ethanol. In addition, α-OH was found to promote the generation of aryl-ketone products. The 4-methoxy-styrene contents of 1-ethyl-benzene-2-(2-methoxy-phenol) and 1-(4-methoxy-phenoxy)-2-(2-methoxy-phenol)-ethanol at 500°C were 36.1% and 31.3%, respectively, higher than the styrene content of 1-benzyl-2-(2-methoxy-phenol)-ethanol (26.3%). The content of acetophenone was only 0.3% in 1-ethyl-benzene-2-(2-methoxy-phenol), but the yields of acetophenone and 4-methoxy-acetophenone were 16.7% and 19.6% in 1-benzyl-2-(2-methoxy-phenol)-ethanol and 1-(4-methoxy-phenoxy)-2-(2-methoxy-phenol)-ethanol, respectively.

ECO-FRIENDLY PRODUCTION OF CHEMICALS 1. IMPROVEMENT OF ENZYMATIC PRODUCTION OF ACETOPHENONE BY DIRECT EXTRACTION

Acetophenone can be enzymatically produced by conversion of methylbenzylamine using transaminase. The enzymatic process is strongly affected by the product inhibition, thus requiring the acetophenone removal from the media during its synthesis. In this purpose, the individual and selective extraction of acetophenone and methylbenzylamine with the biocompatible solvent nheptane containing 1-octanol, D2EHPA or TOA has been analyzed at three values of pH (5, 7, and 9). Regardless of the solvent used and pH-value, the highest efficiency has been reached for extraction of acetophenone, the difference between the extraction yields of acetophenone and methylbenzylamine being amplified during the separation of these compounds from their mixture. On the basis of the experimental selectivity factors and taking into consideration both the possible loss of substrate from the media and the pH required for enzymatic reaction, pH = 7, it has been concluded that the optimum solvent combination is the mixture between n-heptane and 1-octanol. This solvent mixture allowed reaching high selectivity factor of 315, corresponding to the extraction yield of acetophenone of 94.5 % and of methylbenzylamine of only 0.3 %.

Solvent-Free Microwave-Assisted Peroxidative Oxidation of Alcohols Catalyzed by Iron(III)-TEMPO Catalytic Systems

The iron(III) complexes [H(EtOH)][FeCl2(L)2] (1), [H2bipy]1/2[FeCl2(L)2].DMF (2) and [FeCl2(L)(2,2′-bipy)] (3) (L = 3-amino-2-pyrazinecarboxylate; H2bipy = doubly protonated 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine, DMF = dimethylformamide) have been synthesized and fully characterized by IR, elemental and single-crystal X-ray diffraction analyses, as well as by electrochemical methods. Complexes 1 and 2 have similar mononuclear structures containing different guest molecules (protonated ethanol for 1 and doubly protonated 4,4′-bipyridine for 2) in their lattices, whereas the complex 3 has one 3-amino-2-pyrazinecarboxylate and a 2,2′-bipyridine ligand. They show a high catalytic activity for the low power (10 W) solvent-free microwave assisted peroxidative oxidation of 1-phenylethanol, leading, in the presence of TEMPO, to quantitative yields of acetophenone [TOFs up to 8.1 × 103 h−1, (3)] after 1 h. Moreover, the catalysts are of easy recovery and reused, at least for four consecutive cycles, maintaining 83 % of the initial activity and concomitant rather high selectivity. 3-Amino-2-pyrazinecarboxylic acid is used to synthesize three new iron(III) complexes which act as heterogeneous catalysts for the solvent-free microwave-assisted peroxidative oxidation of 1-phenylethanol.

A Trinuclear Au I Complex with Different R 3 P–Au Centers: Synthesis, Characterization, and Synergetic Catalysis for Hydration of Phenylacetylene

A trinuclear AuI complex (3A) was synthesized and fully characterized relative to mononuclear (1A) and dinuclear (2A) complexes. The single-crystal X-ray diffraction analyses show that the AuI-centered vectors in each of the AuI complexes (1A–3A) are all in a slightly distorted linear configuration, in which the AuI center is diagonally coordinated by one Cl– and one phosphine ligand. In 3A each P–Au–Cl vector is radially attached to the core of 1-(thiazol-2′-yl)imidazolyl, which does not allow the short contact between the Au atoms to develop an aurophilic AuI–AuI interaction. Every P–Au–Cl moiety in 3A is different to each other in terms of Au–P and Au–Cl bond lengths, P–Au–Cl bond angles, and P–Au–Cl configurable orientation owing to the different coordinating ability of the involved phosphines. When 1A–3A were employed as the precatalysts for the hydration of phenylacetylene in aqueous methanol media without the involvement of any auxiliary additive, and at the same benchmark Au concentration, the reaction over 3A proceeded selectively according to Markovnikov's rule with the highest yield of acetophenone relative to those over 2A and 1A. This indicates that the catalytic performance of 3A is the outcome of the synergetic effect of the three different R3P–Au centers, in which each R3P–Au site plays an individual role in activating the substrate molecule.

Nitrogen-doped dual mesoporous carbon for the selective oxidation of ethylbenzene.

A nanocasting method to fabricate nitrogen-doped dual mesoporous carbon is proposed by the carbonization of nitrile functional ionic liquid (FIL) grafted SBA-15 for the first time. These carbon materials have high nitrogen content (12.8%), large specific surface areas (763 m(2) g(-1)) and uniform rod morphologies, which are derived from FILs grafted on the surface of SBA-15. Furthermore, by adjusting the impregnation amount of ionic liquids on SBA-15, pore structures of these carbon materials can be adjusted from single to dual mesopores. The developed dual mesoporous carbon materials exhibit good catalytic performance in the selective oxidation of ethylbenzene, ascribed to the promoting effects of nitrogen-doping, high surface area and dual mesostructure. It may be concluded that the dual mesostructure has an advantage over a single mesostructure to obtain a fast mass transport rate, resulting in higher acetophenone yield.

ChemInform Abstract: The Ionic Mononuclear and Trinuclear Au(I)‐Complexes Ligated by Phosphine‐Functionalized Ionic Liquids: Synthesis, Characterization, and Catalysis to Hydration of Phenylacetylene.

Abstract A series of ionic Au(I)-complexes ligated by the phosphine-functionalized ionic liquids were synthesized and characterized, which are composed of the Au(I)-complex cation and the counteranion of OTf−, AuCl4−, or PF6−, respectively. The single crystal X-ray diffraction analyses show that the Au(I)-centered vector in 1A, 1B, 2A, 3A, and 4A all possess the slightly twisted linear geometry, and in each individual the Au(I)-center is coordinated by one chlorine and one imidazolium-based phosphine. The aggregation of 1B in acetone can lead to the formation of the trinuclear Au(I)-complex of 1C due to the aurophilic Au(I)–Au(I) interaction, the electrostatic attraction, and the steric preference. When these ionic Au-complexes were employed as precatalysts for hydration of phenylacetylene in aqueous-methanol media, the reaction proceeded selectively according to Markovnikov's rule with moderate to high yields of acetophenone. The highest activities were achieved over 2A with hydrophobic PF6− as the counteranion and the trinuclear 1C under mild conditions (75 °C, 2 h), in conjunction with the additive of proton acid H2SO4. The ion-pair effect on the catalytic performance of the corresponding Au(I)-complexes, coming from the phosphine-ligated cations and the counteranions, were investigated.

Au(I)-complexes ligated by hybrid P,S,N-ligands as the efficient catalysts for hydration of phenylacetylene

The incorporation of –PPh2 group in the parent molecule of 1-(thiazol-2′-yl)-imidazole afforded the hybrid P,S,N-ligands of 1 and 2 respectively. The former was quarternized by MeOTf to give the ionic hybrid P,S-ligand of 1′. The single crystal X-ray diffraction analyses of the corresponding mono-nuclear Au(I)-complexes of 1A and 2A indicate that the Au(I)-centered vectors in each are in a slightly distorted linear configuration, in which Au(I) center is diagonally coordinated by one Cl− and one phosphine without the coordinating interaction to N (or S)-donors. When the mono-nuclear Au(I)-complexes of 1A, 1′A, and 2A were employed as the catalysts for hydrations of phenylacetylene in aqueous-methanol media with the involvement of AgOTf and H2SO4, the reactions over 1A proceeded selectively according to Markovnikov's rule with much high yields of acetophenone than those over 1′A and 2A, indicating that the available additional S-, and N-donors in 1A with less steric hindrance synergetically protected the active Au(I)-complex species against deactivation during the catalytic cycle.

The ionic mononuclear and trinuclear Au(I)-complexes ligated by phosphine-functionalized ionic liquids: Synthesis, characterization, and catalysis to hydration of phenylacetylene

A series of ionic Au(I)-complexes ligated by the phosphine-functionalized ionic liquids were synthesized and characterized, which are composed of the Au(I)-complex cation and the counteranion of OTf−, AuCl4−, or PF6−, respectively. The single crystal X-ray diffraction analyses show that the Au(I)-centered vector in 1A, 1B, 2A, 3A, and 4A all possess the slightly twisted linear geometry, and in each individual the Au(I)-center is coordinated by one chlorine and one imidazolium-based phosphine. The aggregation of 1B in acetone can lead to the formation of the trinuclear Au(I)-complex of 1C due to the aurophilic Au(I)–Au(I) interaction, the electrostatic attraction, and the steric preference. When these ionic Au-complexes were employed as precatalysts for hydration of phenylacetylene in aqueous-methanol media, the reaction proceeded selectively according to Markovnikov's rule with moderate to high yields of acetophenone. The highest activities were achieved over 2A with hydrophobic PF6− as the counteranion and the trinuclear 1C under mild conditions (75 °C, 2 h), in conjunction with the additive of proton acid H2SO4. The ion-pair effect on the catalytic performance of the corresponding Au(I)-complexes, coming from the phosphine-ligated cations and the counteranions, were investigated.

Solvent-controlled synthesis of tetranuclear cage-like copper(ii) silsesquioxanes. Remarkable features of the cage structures and their high catalytic activity in oxidation with peroxides

Two principally different in their molecular architecture isomeric tetranuclear copper(ii) silsesquioxanes, "Globule"-like compound [(PhSiO1.5)12(CuO)4(NaO0.5)4] (1) and "Sandwich"-like derivative [(PhSiO1.5)6(CuO)4(NaO0.5)4(PhSiO1.5)6] (2), were synthesized by the partial cleavage of polymeric copper(ii) silsesquioxane [(PhSiO1.5)2(CuO)]n by tetraphenylcyclotetrasiloxanolate. The route leading to the formation of either 1 or 2 entirely depends on the nature and composition of the solvent used for this reaction. Thus, the process in an ethanol-1-butanol solution gives compound 1. When a 1,4-dioxane-methanol mixture was used, compound 2 was prepared. The structures and unusual crystal packing of the cages were confirmed by the X-ray studies. It has been found that the reaction of benzene with H2O2 in acetonitrile solution at 50 °C catalyzed by 1 requires addition of trifluoroacetic acid (TFA) in low concentration and gives phenol with a turnover number (TON) of 250 after 3 h. The initial reaction rate W0 linearly depends on the concentration of catalyst 2. The oxidation of 1-phenylethanol to acetophenone with hydrogen peroxide catalyzed by complex 1 in the presence of TFA is not efficient. In contrast, 1 exhibited excellent activity in the oxidation with tert-butyl hydroperoxide (TBHP) in the absence of any acid (the yield of acetophenone was close to the quantitative, TON attained 475 after 2 h). A kinetic study of this reaction led to the conclusion that the process occurs with the participation of radicals tert-BuO˙ produced in the Cu-promoted decomposition of TBHP. The mode of dependence of W0 on the initial concentration of TBHP indicates the formation of an intermediate adduct between the catalyst 1 and TBHP (characterized by the equilibrium constant K1≈ 2 M(-1) for the conditions of conducted experiments) followed by subsequent decomposition of the adduct (k2≈ 0.2 s(-1)) to generate an intermediate species tert-BuO˙ which induces the alcohol oxidation.

Role of vanadium and pyridine in heteropolycompounds for selective oxidation of alcohols with hydrogen peroxide

This study describes the application of heteropolyacids H3PMo12O40, H4SiMo12O40, H4PMo11VO40, H5PMo10V2O40, H9PMo6V6O40, and a hybrid pyridine-modified heteropolyacid with Keggin structure for selective oxidation of alcohols to ketones or aldehydes using aqueous hydrogen peroxide and acetonitrile as solvent. Performance of these different catalysts in 1-phenylethanol oxidation was studied. Influence of reaction temperature, amount of catalyst and hydrogen peroxide and reaction time on the yield of acetophenone was investigated to obtain optimal reaction conditions. Oxidation ability of the catalyst depended on the number of vanadium atoms present in the Keggin ion and to a lesser extent on pyridine substitution in the Keggin secondary structure. In order to explore the applicability of the method for selective oxidation of alcohols to ketones or aldehydes, various alcohols were investigated according to the general procedure using hybrid pyridine-modified heteropolyacid. This study describes the application of heteropolyacids H3PMo12O40, H4SiMo12O40, H4PMo11VO40, H5PMo10V2O40, H9PMo6V6O40, and a hybrid pyridine-modified heteropolyacid with Keggin structure for selective oxidation of alcohols to ketones or aldehydes using aqueous hydrogen peroxide and acetonitrile as solvents.

Cr-Substituted Mesoporous Aluminophosphate Molecular Sieve: Synthesis, Characterization, Crystallization Kinetics and Catalytic Activity

Cr-substituted mesoporous aluminophosphate molecular sieve (Cr-MAP) was synthesized and characterized. Crystallization kinetics curves measured as an index to the relative degree of crystallinity, according to the Arrhenius equation to calculate the apparent nucleation activation energy and crystal growth activation energy of Cr-MAP, which was 63.7 and 14.7 kJ• mol-1, respectively. Cr-MAP had highly catalytic activity for fabricating acetophenone by selectively oxizing ethylbenzene. Using tert-butylhydroperoxide as oxidant and chlorobenzene as solvent at 100 °C for 8 h, acetophenone selectivity, acetophenone yield and ethylbenzene conversion reaches 85.4, 62.2 and 72.8 %, respectively.