Showing papers on "Cyclohexanone published in 2020"

Study on boron and fluorine-doped C3N4 as a solid activator for cyclohexane oxidation with H2O2 catalyzed by 8-quinolinolato ironIII complexes under visible light irradiation

Abstract: This paper discloses that boron and fluorine-doped carbon nitride (C3N4BF), as a solid activator, can efficiently accelerate the relatively inert 5,7-dichloro-8-quinolinolato iron(III) complex (FeIII(Qb)3) to photo-catalyze the oxidation of cyclohexane to cyclohexanol and cyclohexanone by hydrogen peroxide (H2O2) in acetonitrile (MeCN) under visible light irradiation and achieve 25.87 % cyclohexane conversion, which is almost twice as high as without it and obviously higher than the results obtained using ordinary C3N4 as an activator or under thermo-catalysis. Furthermore, its such activation effect on FeIII(Qb)3 photocatalysis is also observed in the H2O2-involved oxidation of other substrates such as toluene, ethylbenzene, benzyl alcohol and thioanisole. UV–vis and PL spectra, photocurrent transient measurements and theoretical calculations support that C3N4 and especially C3N4BF can form strong π-π stacking interactions with FeIII(Qb)3, thus inducing a weakly structural distortion of FeIII(Qb)3 and enhancing its photo-reductive activation via capturing the photo-generated electrons of the activator. As a result, the synergistic catalytic effect of FeIII(Qb)3 with C3N4/especillly C3N4BF can significantly accelerate the above thermo-/especially photo-oxidations.

Synthesis of Multilevel Structured MoS2@Cu/Cu2O@C Visible-Light-Driven Photocatalyst Derived from MOF–Guest Polyhedra for Cyclohexane Oxidation

Abstract: Selective oxidation of cyclohexane to KA oil (cyclohexanol and cyclohexanone) is one of the most important industrial procedure. In this study, we reported a remarkably enhanced cyclohexane oxidati...

Palladium Nanoparticles Anchored on Sustainable Chitin for Phenol Hydrogenation to Cyclohexanone

Abstract: A kind of natural, sustainable, and abundant biomass, chitin, is used as support to load palladium nanoparticles catalyst (Pd–chitin) for the transfer hydrogenation of phenolic compounds to ketones...

Role of the metal-support interface in the hydrodeoxygenation reaction of phenol

Abstract: In this work, the effect of interfacial sites between Pd particles and Nb2O5 species is investigated by testing a series of Pd-Nb2O5/SiO2 catalysts with different niobium loadings for the HDO reaction of phenol in the gas phase. Important differences in the selectivity to deoxygenated product were observed depending on the presence of niobium oxide close to Pd particles, which reveals the key role of the type of active phase in the control of reaction steps. It was found that Pd/SiO2 catalyst promotes hydrogenation pathways, producing cyclohexanone as the major product. For Pd-Nb2O5/SiO2 catalyst containing a Nb/Pd molar ratio of 0.5, a sharp increase in the selectivity to benzene is observed (7.5-fold). Increasing the Nb/Pd molar ratio, the formation of benzene is enhanced. The results showed that the Pd-Nb2O5 interface, composed by an oxophilic oxide in the perimeter of the metal particle, is responsible for the activation of the C O bond, promoting the deoxygenation reaction.

Toward Hydrogen Economy: Selective Guaiacol Hydrogenolysis under Ambient Hydrogen Pressure

Abstract: The conversion of guaiacol into the nylon precursors, cyclohexanol and cyclohexanone, is catalyzed by palladium supported on high surface area ceria (Pd/HS CeO2) under mild conditions (100 °C, ≤1 bar H2) via sequential hydrodemethoxylation and hydrogenation. In contrast, the 2-methoxycyclohexanol side product is generated by direct guaiacol hydrogenation. Reaction selectivity is determined by competing C O bond hydrogenolysis versus arene hydrogenation. Hydrogenolysis selectivity increases as H2 pressure decreases, and over 80 % H2 is incorporated into the products at 1 bar H2. Higher reactivity of guaiacol than anisole implies that the hydroxyl group is essential in Pd/HS CeO2 catalysis. Participation of water in the conversion is evidenced by deuterium incorporation at non-exchangeable positions when the reaction is performed in D2O. The combination of near quantitative mass balance of H2, high recyclability, and use of water as a solvent offers a simple, green and efficient conversion of lignin-derived aromatics into commercial products.

Electrocatalytic Hydrogenation of Guaiacol in Diverse Electrolytes Using a Stirred Slurry Reactor.

Abstract: Electrocatalytic hydrogenation (ECH) of guaiacol was performed in a stirred slurry electrochemical reactor (SSER) using 5 wt % Pt/C catalyst in the cathode compartment. Different pairs of acid (H2 SO4 ), neutral (NaCl), and alkaline (NaOH) catholyte-anolyte combinations separated by a Nafion® 117 cation exchange membrane, were investigated by galvanostatic and potentiostatic electrolysis to probe the electrolyte and proton concentration effect on guaiacol conversion, product distribution, and Faradaic efficiency. The acid-acid and neutral-acid pairs were found to be the most effective. In the case of the neutral-acid pair, proton diffusion and migration through the membrane from the anolyte to the catholyte supplies the protons required for ECH. Typically, the two major hydrogenation products were cyclohexanol and 2-methoxycyclohexanol. However, ECH at constant cathode superficial current density (-182 mA cm-2 ) and higher temperature (i.e., 60 °C) favored a pathway leading mainly to cyclohexanone. The guaiacol conversion routes were affected by temperature- and cathode potential-dependent surface coverage of adsorbed hydrogen radicals generated through electroreduction of protons.

Photodeposition of Pd onto TiO2 nanowires for aqueous-phase selective hydrogenation of phenolics to cyclohexanones

Abstract: The selective hydrogenation of phenolics to cyclohexanones is an important process in both industrial application and utilization of fossil and renewable feedstocks. However this process remains a challenge in achieving high conversion of phenolics and high selectivity of ketones under mild reaction conditions. In this work, TiO2 nanowires (TNWs) are successfully synthesized by using an integrated method and the ultra-small Pd clusters were then deposited onto the TNWs by photoreduction. The obtained Pd/TNW catalyst shows superior catalytic performances in the hydrogenation of phenolic derivatives to the corresponding cyclohexanones. In particular, a nearly full conversion of phenol with high selectivity (>99.0%) to cyclohexanone can be achieved at 50 °C and 5.0 bar H2 in water. A series of characterization studies by means of XRD, XPS, EPR, FTIR, TPD, STEM, and kinetic studies indicate that abundant exposed Lewis acid and basic sites on the surface of TNWs play important roles in the activation of phenolics and desorption of cyclohexanones, while the Pd clusters by photodeposition can attain a hybrid of Pd0 and Pd2+ species to facilitate the activation of dihydrogenation. A plausible catalytic pathway with synergistic effects of TNWs and Pd species is then proposed.

Selective Hydrogenation of Phenol to Cyclohexanol over Ni/CNT in the Absence of External Hydrogen

Abstract: Transfer hydrogenation is a novel and efficient method to realize the hydrogenation in different chemical reactions and exploring a simple heterogeneous catalyst with high activity is crucial. Ni/CNT was synthesized through a traditional impregnation method, and the detailed physicochemical properties were performed by means of XRD, TEM, XPS, BET, and ICP analysis. Through the screening of loading amounts, solvents, reaction temperature, and reaction time, 20% Ni/CNT achieves an almost complete conversion of phenol after 60 min at 220 °C in the absence of external hydrogen. Furthermore, the catalytic system is carried out on a variety of phenol derivatives for the generation of corresponding cyclohexanols with good to excellent results. The mechanism suggests that the hydrogenation of phenol to cyclohexanone is the first step, while the hydrogenation of cyclohexanone for the generation of cyclohexanol takes place in a successive step. Moreover, Ni/CNT catalyst can be magnetically recovered and reused in the next test for succeeding four times.

Improving the activity in hydrodechlorination of Pd/C catalysts by nitrogen doping of activated carbon supports

Abstract: Aqueous phase 4-chlorophenol hydrodechlorination reaction was used to study the effect of N-doping of activated carbon support on the catalytic activity of Pd catalysts. Activated carbon was doped using pyridine and 1,10-phenantroline, reaching nitrogen contents of 0.42–1.22 and 1.35–4.19 % (w), respectively. All catalysts (0.75 % Pd w, carbon basis) showed relatively large Pd nanoparticles (35−55 nm), but they exhibited fast and complete 4-chlorophenol disappearance in batch experiments. In runs at 30 °C 4-chlorophenol disappearance was mainly ascribed to hydrodechlorination, although N-doping of the support also increased adsorption. Catalysts with supports doped with pyridine yielded higher 4-chlorophenol disappearance rate in spite of lower bulk nitrogen content, however they showed higher concentration of nitrogen species at the external surface and lower loss of surface area during the doping. 4-chlorophenol disappearance rate was boosted at 60 °C, with minor differences between catalysts with undoped and N-doped supports, but generation of cyclohexanone was only observed for the ones with doped support. Phenol generation simultaneous to 4-chlorophenol disappearance was observed with all the catalysts. However, subsequent hydrogenation to cyclohexanone ocurred only with the catalysts supported on N-doped activated carbon.

Recent Progress in Adipic Acid Synthesis Over Heterogeneous Catalysts

Abstract: Adipic acid is one of the most important feedstocks for producing resins, nylons, lubricants, plasticizers. Current industrial petrochemical process, producing adipic acid from KA oil, catalyzed by nitric acid, has a serious pollution to the environment, due to the formation of waste nitrous oxide. Hence, developing cleaner methods to produce adipic acid has attracted much attention of both industry and academia. This mini-review article discussed advances on adipic acid synthesis from bio-renewable feedstocks, as well as most recent progress on cleaner technology from fossil fuels over novel catalytic materials. Synthetic routes for bio-derived adipic acid will be critically revised, while novel catalytic materials with high atomic efficiency for fossil-derived adipic acid will be discussed and compared. This work on recent advances in green adipic acid production will provide insights and guidance to further study of various other industrial processes for producing nylon precursors.

Highly Efficient Phenol Hydrogenation to Cyclohexanone over Pd@CN-rGO in Aqueous Phase

Abstract: Selective hydrogenation of phenol is a green strategy to produce cyclohexanone. Achieving high phenol conversion and cyclohexanone selectivity under mild conditions is a significant challenge in th...

Acidochromic Behavior of Dibenzylidene Cyclohexanone-Based Bischalcone: Experimental and Theoretical Study.

Abstract: Synthesis and characterization of substituted 2,6-dibenzylidene cyclohexanone-based bischalcone derivatives and their optimized geometries were investigated by density functional theory. The synthe...

CO2 activation through C–N, C–O and C–C bond formation

Abstract: A comparative model for the chemisorption of CO2 was explored via three representative reaction pathways: carboxylation of cyclohexanone, carbonation of cyclohexanol, and carbamation of cyclohexylamine. The model substrates were activated using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, an amidine superbase). For each of these reactions, the formation of the corresponding CO2 adducts was confirmed by 13C nuclear magnetic resonance and Fourier-transform infrared spectroscopy measurements. It was demonstrated that CO2 fixation occurred through either an enol-CO2 adduct (i.e. carboxylation), proton shuttling process (i.e. carbonation), or self-activation mechanism (i.e. carbamation). Volumetric adsorption measurements indicated that cyclohexanol was superior in its uptake capacity (11.7 mmol CO2 g−1 sorbent) in comparison to cyclohexylamine (9.3 mmol CO2 g−1 sorbent) or cyclohexanone (8.5 mmol CO2 g−1 sorbent). As supported by density functional theory calculations, this trend was expected given the fact that the carbonation reaction proceeded through a more thermodynamically favorable reaction process.

First Synthesis for Bis-Spirothiazolidine Derivatives as a Novel Heterocyclic Framework and Their Biological Activity.

Abstract: BACKGROUND Spirothiazolidines are versatile synthetic scaffold possessing wide spectrum of biological interests involving potential anticancer activity. OBJECTIVE To report the first synthesis of Bis Spiro-thiazolidine as a novel heterocyclic ring system. METHODS One-pot three-component reaction including condensation of p-phenyllene diamine; cyclohexanone and thioglycolic acid produced Spiro-thiazolidine 4, which underwent further condensation with cyclohexanone and thioglycolic acid with equimolar ratio to introduce Bis-Spiothiazolidine 5 as the first synthesis. Also, bis spiro-thiazolidine arylidene derivatives 6-13 were synthesized by the reaction of Bis-Spiothiazolidine 5 with different aromatic benzaldehydes. RESULTS Four compounds 13, 12, 9 and 11 have shown highly significant anticancer activity compared to Doxorubicin® (positive control) against Human liver carcinoma (HepG2) and Human Normal Retina pigmented epithelium (RPE-1) cell lines. CONCLUSION The novel bis-spirothiazolidine deriviatives have been synthesized for the first time and showed excellent anticancer activities compare with the corresponding spirothiazolidine derivatives.

Liquid–Liquid Equilibrium for Ternary Mixture Water + (n-Propanol/Isopropanol) + Cyclohexanone at 298.15 and 308.15 K

Abstract: For separation of the azeotropes of n-propanol (NPA) + water and isopropanol (IPA) + water by liquid–liquid extraction, cyclohexanone was selected as the extraction solvent. The liquid–liquid equil...