Conversion Of Acetophenone Research Articles

Hydrodeoxygenation of acetophenone over a sulfonated carbon-supported ruthenium catalyst

A sulfonated active carbon supported Ru catalyst was prepared and tested in hydrodeoxygenation of acetophenone. The catalysts were characterized by XRD, TEM, N2 adsorption and NH3-TPD. The influences of reaction parameters on the conversion and selectivity were studied. An acetophenone conversion of 100% with total 90% selectivity of deoxygenated products was achieved at 150°C over this catalyst, which was more active than the active carbon (AC) or SiO2 supported Ru catalysts. The enhanced performance of sulfonated AC supported Ru was attributed to the stronger acid sites and the better dispersion of Ru species. Moreover, such a catalyst was stable under the current reaction conditions and can be reused several times without obvious loss of activity.

Ionic [Ru] complex with recyclability by electro-adsorption for efficient catalytic transfer hydrogenation of aryl ketones

Abstract The efficient reuse of homogeneous catalyst is important. Cation complex of [Ru(η6-p-cymene)(PPh3)(CH3CN) Cl]PF6 with different ligands was synthesized and characterized by infrared spectroscopy (IR), 1H-, 13C- and 31P-nuclear magnetic resonance spectroscopy (1H-, 13C- and 31P-NMR), element analysis (EA), and high resolution mass spectrometry (HR-MS). The complex was used as a catalyst for the hydrogen transfer reduction of carbonyl for the first time, presenting an excellent catalytic performance of 89%–98% conversion of acetophenone and its derivatives. The catalyst may be efficiently reused by the electro-adsorption of 10 times to one catalyst recovery. The cation [Ru] complex presented advantages of both homogeneous and heterogeneous catalysts.

Fe-polyaniline composite nanofiber catalyst for chemoselective hydrolysis of oxime

A facile chemoselective one-pot strategy for the deprotection of oxime has been developed using Fe0-polyaniline composite nanofiber (Fe0-PANI), as a catalyst. Nano material based Fe0-PANI catalyst has been synthesized via in-situ polymerization of ANI monomer and followed by reductive deposition of Fe0 onto PANI matrix. The catalyst was characterized by FE-SEM, HR-TEM, BET, XRD, ATR-FTIR, XPS and VSM techniques. The scope of the transformation was studied for aryl, alkyl and heteroarylketoxime with excellent chemoselectivity (>99%). Mechanistic investigations suggested the involvement of a cationic intermediate with Fe3+ active catalytic species. Substituent effect showed a linear free energy relationship. The activation energy (Ea) was calculated to be 17.46 kJ mol−1 for acetophenone oxime to acetophenone conversion. The recyclability of the catalyst demonstrated up to 10 cycles without any significant loss of efficiency. Based on the preliminary experiments a plausible mechanism has been proposed involving a carbocationic intermediate.

Design of tandem catalyst by co-immobilization of metal and enzyme on mesoporous foam for cascaded synthesis of (R)-phenyl ethyl acetate

Co-operative and complex catalytic transformations in biological systems comprise a set of diverse reactions in a single compartment. Herein, palladium and Cal B lipase were sequentially co-immobilized in the microenvironment of mesocellular foam to mimic biological systems and fully characterized. At optimal conditions, complete hydrogenation of acetophenone was achieved at atmospheric hydrogen pressure. The in-situ formed racemic 1-phenyl ethanol was then kinetically resolved selectively using lipase immobilized on the same support using vinyl acetate as (R)-phenylethyl acetate. For comparison, a single pot reaction was also conducted wherein supply of hydrogen was discontinued after complete conversion of acetophenone and further kinetic resolution was carried out in nitrogen atmosphere by adding vinyl acetate to system. The reaction showed complete conversion in 10h for hydrogenation step while lipase catalyzed gave 49.11% of selectivity towards R enantiomer with respect to racemic mixture with 100% enantiomeric excess (ee). The designed tandem catalyst avoids the use of multiple supports, purification of intermediate product as well as use of multiple reactors making process green and economical.

Modification of the response of olfactory receptors to acetophenone by CYP1a2

Olfaction is mediated by the binding of odorant molecules to olfactory receptors (ORs). There are numerous proteins in the nasal mucus, and they contribute to olfaction through various mechanisms. Cytochrome P450 (CYP) family members are known to be present in the olfactory epithelium and are thought to affect olfaction by enzymatic conversion of odorant molecules. In this study, we examined the effects of CYPs on the ligand responses of ORs in heterologous cells. Among the CYPs tested, co-expression of CYP1a2 significantly affected the responses of various ORs, including MOR161-2, to acetophenone. Conversion of acetophenone to methyl salicylate was observed in the medium of CYP1a2-expressing cells. MOR161-2-expressing cells exhibited significantly greater responses to methyl salicylate than to acetophenone. Finally, we analyzed the responses of olfactory neurons expressing MOR161-2 in vivo using the phosphorylated ribosomal protein S6 as a marker. MOR161-2 responded to both acetophenone and methyl salicylate in vivo. When the olfactory mucus was washed out by the injection of PBS to mouse nasal cavity, the response of MOR161-2 to acetophenone was reduced, while that to methyl salicylate did not change. Our data suggest that CYP1a2 affects OR activation by converting acetophenone to methyl salicylate.

Magnetically Recoverable Pd/Fe3 O4 Core-Shell Nanowire Clusters with Increased Hydrogenation Activity.

Core-shell nanostructures are promising candidates for the next generation of catalysts due to synergistic effects which can arise from having two active species in close contact, leading to increased activity. Likewise, catalysts displaying added functionality, such as a magnetic response, can have increased scientific and industrial potential. Here, Pd/Fe3 O4 core-shell nanowire clusters are synthesized and applied as hydrogenation catalysts for an industrially important hydrogenation reaction: the conversion of acetophenone to 1-phenylethanol. During synthesis, the palladium nanowires self-assemble into clusters which act as a high-surface-area framework for the growth of a magnetic iron oxide shell. This material demonstrates excellent catalytic activity due to the presence of palladium while the strong magnetic properties provided by the iron oxide shell enable facile catalyst recovery.

The Immobilization of a Transfer Hydrogenation Catalyst on Colloidal Particles

AbstractIn this paper, we report a new synthetic procedure to immobilize a transfer hydrogenation catalyst on the surface of colloidal polystyrene particles. Using supports of colloidal dimensions allows for combining a relatively high surface area for catalyst binding, mobility of the catalyst, and facile recovery by centrifugation or sedimentation. The immobilization procedure relies on the covalent attachment of terpyridine moieties on the particle surface. These immobilized terpyridines are subsequently employed as colloidal ligands, which participate in the formation of an active ruthenium‐based transfer hydrogenation catalyst. The resulting functional colloidal particles successfully catalyze the transfer hydrogenation of acetophenone with 2‐propanol as the hydrogen donor. Thorough analysis of the chemical composition of the colloidal surface led to the determination of the catalyst loading per particle. This enabled us to conduct reference hydrogenations with equal concentrations of the homogeneous transfer hydrogenation catalyst to probe the effect of the immobilization procedure on the catalytic activity. Despite a decrease in transfer hydrogenation activity, full acetophenone conversion is still achievable within 24 h. Preliminary experiments show that the catalytic colloids are recyclable without significant loss of transfer hydrogenation activity.

Eco-friendly, green and sustainable endo-templated in-situ synthesis of MgO-incorporated carbon from sea salt: An efficient heterogeneous base catalyst

This paper reports an eco-friendly and sustainable approach for the in-situ synthesis of MgO-incorporated carbon (MgO@C) using sea salt and sucrose as the magnesium and carbon sources, respectively. Sea salt was used as an endo-template for the formation of microporosity in a carbon texture, resulting in the maximal surface area, 497m2/g with the in-situ incorporation of MgO. The present methodology has the advantage of an acid/base-free approach with simple water washing for leaching of the template, which can be regenerated and reused after simple drying. The resulting MgO@C showed better performance as a heterogeneous base catalyst for the synthesis of chalcones. Among the synthesized MgO@C catalysts, the MgO@C obtained using sucrose/sea salt ratio of 1:4 with 28wt% MgO loading resulted in higher catalytic activity, i.e., maximal conversion of acetophenone (95%) within 90min, compared with another ratio.

Asymmetric Bioconversion of Acetophenone in Nano-Sized Emulsion Using Rhizopus oryzae.

The fungal morphologies and pellet sizes were controlled in acetophenone reduction by Rhizopus oryzae. The acetophenone conversion and (S)-phenylethanol enantiomeric excesses (e.e.) reached the peak after 72 h of incubation when using pellets with 0.54 mm diameter, which showed an excellent performance compared with suspended mycelia, clumps, and pellets with 0.65 or 0.75 mm diameter. Furthermore, nano-sized acetophenone was used as a substrate to improve the performances of biotransformation work. The results showed that the conversion of nanometric acetophenone and (S)-phenylethanol e.e. reached the maximum (both >99%) after 32 h of incubation when using 0.54 mm diameter pellets, at least 24 h in advance of the control group. On the other hand, Tween 80 and 1, 2-propylene glycol showed low or no toxicity to cells. In conclusion, pellets and acetophenone nanoemulsions synergistically result in superior performances of acetophenone reduction.

Chemical modification and evaluation of omega-transaminase enzyme isolated from moraxella sp. NCIM 2795

The enzyme transaminase carry potential to be used for industrial applications directed towards production of chiral amines and amino acids. The present study was directed towards isolation, purification and immobilization of one such transaminase from Moraxella sp. NCIM 2795. Partial purification of enzyme was performed by ammonium sulphate precipitation technique. The partially purified enzyme was subjected to different immobilization techniques like physical adsorption, ionic binding, covalent binding using chitin and chitosan beads respectively. The effect of various immobilization and chemical modification parameters along with the effect of amine donors, storage stability and reusability on transaminase enzyme activity were evaluated. The transaminase enzyme assays for acetophenone conversion were performed by GC.

Kinetics of acetophenone reduction to (R)-1-phenylethanol by a whole-cell Pichia capsulata biocatalyst

(R)-1-phenylethanol is an important substance in fragrance and flavor industry. In this work, the reduction of acetophenone to (R)-1-phenylethanol in an aqueous medium was examined using Pichia capsulata as a whole-cell biocatalyst. Progress curve and initial rate measurements were used to obtain kinetic data. The experiments were carried out at pH 5, temperature of 25 °C, and in the presence of glucose to maintain in vivo regeneration of NADH. A model of the reversible reaction kinetics considering the substrate inhibition of the forward reaction was developed. Five kinetic parameters of this model were determined by a simultaneous fit of a reaction rate dependence on substrate concentration and 18 substrate and product concentration progress curves with very good accuracy. Equilibrium constant of the reaction and equilibrium conversion of acetophenone to (R)-1-phenylethanol were 13.7 and 93%, respectively.

Enzyme-Modified Particles for Selective Biocatalytic Hydrogenation by Hydrogen-Driven NADH Recycling.

We describe a new approach to selective H2-driven hydrogenation that exploits a sequence of enzymes immobilised on carbon particles. We used a catalyst system that comprised alcohol dehydrogenase, hydrogenase and an NAD+ reductase on carbon black to demonstrate a greater than 98 % conversion of acetophenone to phenylethanol. Oxidation of H2 by the hydrogenase provides electrons through the carbon for NAD+ reduction to recycle the NADH cofactor required by the alcohol dehydrogenase. This biocatalytic system operates over the pH range 6–8 or in un-buffered water, and can function at low concentrations of the cofactor (10 μm NAD+) and at H2 partial pressures below 1 bar. Total turnover numbers >130 000 during acetophenone reduction indicate high enzyme stability, and the immobilised enzymes can be recovered by a simple centrifugation step and re-used several times. This offers a route to convenient, atom-efficient operation of NADH-dependent oxidoreductases for selective hydrogenation catalysis.

Biotransformation of acetophenone to R-1-phenylethanol with immobilized Pichia capsulata in batch reactor

Abstract Biotransformation of acetophenone to R-1-phenylethanol with Pichia capsulata immobilized in Caalginate gel beads was studied. Experiments were carried out in a batch reactor stirred on an orbital shaker (300 rpm) at 25 ℃. Based on experimental data, uncoupled parameters of reaction kinetics (measurements with free cells) and diffusion coefficients (sorption method) were estimated. The model expressing the conversion of acetophenone with immobilized cells in the batch reactor consisted of mass balance equations of acetophenone and R-1-phenylethanol in the liquid and solid phases. A satisfactory agreement between the experimental and predicted values of acetophenone and R-1-phenylethanol concentrations was achieved

Seed-mediated synthesis of dendritic platinum nanostructures with high catalytic activity for aqueous-phase hydrogenation of acetophenone

This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum (Pt) nanoparticles (NPs) at low temperatures of 55–60 °C in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent.It is found that the dendritic Pt NPs (10–150 nm) are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3–5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including: (i) acetophenone conversion rate of > 90%, with smaller dendritic Pt NPs (10–46 nm) offering a higher conversion efficiency; (ii) high chemoselectivity toward carbonyl group (90.6%–91.5%), e.g., the selectivity to 1-phenylethanol is ∼90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 min, under mild reaction conditions (20 °C, 1.5 bar H2 pressure, and 1.5 mol% catalyst). The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.

Photophysics of acetophenone interacting with DNA: why the road to photosensitization is open.

Deoxyribonucleic acid photosensitization, i.e. the photoinduced electron- or energy-transfer of chromophores interacting with DNA, is a crucial phenomenon that triggers important DNA lesions such as pyrimidine dimerization, even upon absorption of relatively low-energy radiation. Oxidative lesions may also be produced via the photoinduced production of reactive oxygen species. Aromatic ketones, and acetophenone in particular, are well known for their sensitization effects. In this contribution we model the structural and dynamical properties of the acetophenone/DNA aggregates as well as their spectroscopic and photophysical properties using high-level hybrid quantum mechanics/molecular mechanics methods. We show that the key steps of the photochemistry of acetophenone in gas phase are conserved in the macromolecular environment and thus an ultrafast singlet-triplet conversion of acetophenone is expected prior to the transfer to DNA.

Diastereoselective self-organization of acetylene and acetophenone molecules into 1-benzoyl-3-hydroxy-cyclopentene in the presence of potassium hydroxide

We have recently found that acetylene and alkyl aromatic and alkyl heteroaromatic ketones in the superbasic system KОН–DMSO (80С, 1 h) underwent instead of Favorskii reaction a unique selective tandem reaction leading in a single preparative stage to the formation of complex functionalized heterocyclic systems with a frontalin scaffold, 7-methylene-6,8dioxabicyclo[3.2.1]octanes in up to 86% yield [1]. Since frontalin and its analogs are well known insect pheromones [2, 3] and mammal hormones [4, 5], this easy stereoselective (a single diastereomer forms among many possible) and one-pot approach to their derivatives opens new opportunities for the development of their preparative chemistry. At the same time the yet unknown aspect of acetylene reactivity has been unexpectedly revealed: Its capability in the presence of strong bases to undergo self-assembly with the capture of suitable nucleophiles into complex difficultly available functionalized molecules often structurally close to naturally occurring substances. Here we preliminary report that at the systematic investigation of the above mentioned reaction by an example of acetophenone we have found an entirely new direction of self-assembly of two acetylene and two acetophenone molecules affording along with the expected 7-methylene-6,8-bicyclo[3.2.1]octane (I) also 1-benzoyl-3-hydroxycyclopentene (II), also in the form of a single diastereomer (Scheme 1). The preparative yield of structural isomers I and II was 43 and 46% respectively at the acetophenone conversion 46% (the conditions were not yet optimized).

Catalytic hydrogen transfer of ketones over atomic layer deposited highly-dispersed platinum nanoparticles supported on multi-walled carbon nanotubes

Hydrogen transfer of ketones, catalyzed by highly-dispersed platinum nanoparticles supported on multi-walled carbon nanotubes (MWCNTs), was studied. Pt nanoparticles were deposited on gram quantities of non-functionalized MWCNTs by atomic layer deposition (ALD) at 300°C, using (methylcyclopentadienyl) trimethylplatinum and oxygen as precursors. TEM analysis showed that ~1.4nm Pt nanoparticles were highly dispersed on MWCNTs. The heterogeneous hydrogen-transfer reactions of acetophenone indicated that an acetophenone conversion of 100% and a 1-phenylethanol selectivity of 99.0% could be obtained with a ketone to Pt mass ratio of 24,690 and a ketone to KOH mass ratio of 22 at 150°C for 5h. The selectivity of the Pt/MWCNT catalyst was higher than that of the commercial Pt/C catalyst, due to the highly-dispersed, uniform Pt nanoparticles and the unique porous structures of the Pt/MWCNT catalyst. The high stability of the Pt/MWCNT catalyst was demonstrated by reutilization of the catalyst. The high reactivity and selectivity of this catalyst for hydrogen transfer reduction were also demonstrated for other ketones.

Catalytic hydrogenation of acetophenone over shape controlled Pd catalysts supported on sheet-like NiO

Cubic, truncated octahedral and hexagonal/triangular Pd/NiO supported catalysts were synthesized and applied in the hydrogenation of acetophenone. The catalysts were characterized by XRD, TEM, XPS and TG–DCS, and the catalytic performances for selective hydrogenation of acetophenone were evaluated under the condition of 80°C, 3h and 1.5MPa pressure of hydrogen in alcohol media without additives. Results showed that the conversion of 19% and selectivity of 92% were achieved by hexagonal/triangular Pd/NiO catalyst. And when truncated octahedral Pd/NiO was used as the catalyst, the conversion of acetophenone was raised to 40%, while the selectivity of 1-phenethanol decreased to 89%. As to cubic Pd/NiO catalyst, the conversion to further improved to 70% and the selectivity of 1-phenethanol went down to 80%.

Ru(II)–arene complexes with N-substituted 3,4-dihydroquinazoline ligands and catalytic activity for transfer hydrogenation reaction

In this study, N-coordinated 3,4-dihydroquinazoline ruthenium(II) complexes were synthesized by the cleavage reaction of [RuCl2(p-cymene)]2 with N-substituted 3,4-dihydroquinazolines. In addition, the X-ray crystal structure of 2,4,6-trimethylbenzyl substituted 3,4-dihydroquinazoline Ru(II) complex (1a) is reported. Furthermore, the resulting piano–stool complexes were evaluated as transfer hydrogenation catalysts for reduction of acetophenone in the presence of 2-propanol and KOH at 82°C. All the complexes showed good to excellent performance after 1h in the conversion of acetophenone to alcohol and the reaction rate was found to be sensitive to changes on the N-substituent. Additionally, the most active catalyst 1a was used in transfer hydrogenation of different ketones to investigate the effect of substituents on ketones.

Selective hydrogenation of acetophenone to 1-phenyl ethanol over nanofibrous Ag-OMS-2 catalysts

Hydrogenation of acetophenone is interesting and poses a challenge in selective conversion to 1-phenyl ethanol which is a perfumery chemical. It is a complex network of series and parallel reactions. Silver incorporated octahedral molecular sieve catalysts (Ag-OMS-2) were synthesized by precipitation method and employed in the hydrogenation of acetophenone to 1-phenyl ethanol (1-PEA). The catalysts were fully characterized by TGA, XRD, SEM, EDX, TPD, TPR and nitrogen adsorption. They show a nano fibrous structure with very high activity toward hydrogenation. Acetophenone conversion increased with an increase in silver loading from 5 to 15% by wt. 15% Ag-OMS-2 showed the highest activity and 100% selectivity to 1-PEA at hydrogen pressure of 10atm and 160°C. Effects of various parameters such as speed of agitation, type of solvent, catalyst loading, acetophenone concentration, and temperature were studied. A kinetic model was built using Langmuir–Hinshelwood–Hougen–Watson mechanism with weak adsorption of all species leading to a power law model. The activation energy was found to be 12.38kcal/mol.