Yield Of Biphenyl Research Articles

Boosting Suzuki coupling reaction via pore expanding and palladium–zinc alloying

A palladium–zinc alloy nanoparticles decorated nitrogen-doped porous carbon catalyst (PdZn30–NC) was synthesized and utilized for Suzuki coupling reaction. The alloying palladium (Pd) with zinc (Zn) and pore expanding are realized simultaneously. Density functional theory (DFT) calculations and experimental studies reveal that the alloying Pd with Zn can lower the energy barrier in Suzuki coupling reaction. Nitrogen adsorption–desorption measurements uncover that pore expansion caused by the zinc nitrate hexahydrate assisted calcination gives rise to the multiplication of mesopore with a pore diameter of 6 nm, which facilitates mass transfer during the reaction. As a result, the alloying Pd with Zn and pore expanding together endow PdZn30–NC with excellent catalytic activity. PdZn30–NC demonstrates exceptional catalytic activity and stability in Suzuki coupling reaction. A high biphenyl yield of 97.7 % within 40 min and stable reusability of 93.3 % yield after five reuse cycles can be achieved. This work not only offers a viable method for Suzuki coupling reaction, but also provides insights for designing new catalysts toward Suzuki coupling reaction.

Design of experiment (DOE) and process optimisation of palladium catalysed biphenyl synthesis

ABSTRACT The effects of time, temperature and catalyst concentration were investigated for an optimised condition of biphenyl synthesis by Suzuki-Miyaura cross-coupling reactions by Neolyst catalysts. The optimisation process was analysed using Box Behnken Face-Centred Experimental Design in Response Surface Methodology (RSM). The design was employed to derive a statistical model for the effect of parameters studied on the yield of biphenyl. The coefficient of determination, r 2 was 0.9883% after model reduction. With an optimum time of 6.63 h, a temperature of 73°C and with minimum catalyst concentration of 0.013 mol% gives the optimum conditions for the maximum yield of biphenyl.

MOF-derived CoP/C catalyst for efficient dibenzothiophene hydrodesulfurization

The design of an active and sulfur-resistant catalyst for dibenzothiophene (DBT) hydrodesulfurization (HDS) in crude oil purification is highly desirable but remains a grand challenge. Here, two carbon-supported cobalt phosphide catalysts Co2P/C and CoP/C, and a reference sample Co/C are successfully synthesized using a metal–organic-frameworks (MOFs) precursor. A P/Co ratio dependence on crystal phases is found, leading to the formation of two pure-phase cobalt phosphide catalysts CoP/C and Co2P/C. Catalyst evaluation in HDS of DBT shows that the CoP/C catalyst exhibits a higher activity and stability than Co2P/C and Co/C, giving a 93.7 % DBT conversion with 100 h stability under 3 MPa and 380 ◦C. Moreover, a 67.4 % biphenyl yield characterizes the dominance of the direct desulfurization (DDS) pathway. The obtained catalytic performance over the CoP/C catalyst is also superior to the published cobalt phosphide catalysts. Multiple characterization techniques co-evidence that the copious specific surface area, efficient electron transport from Co to P, high thermal stability of Co nanoparticles (NPs), and strong sulfur resistance account for the enhanced catalytic performance of CoP/C. The findings of this report suggest that phosphorus-modified cobalt over the carbon support can act as a promising catalyst for the HDS of DBT.

Deciphering Au-manganese oxide nanopetals plasmon–exciton co-driven artificial photosynthesis and Suzuki-Miyaura coupling reactions

Here, we developed three different amorphous structural designs of Mn nanomaterials (nanospheres, nanoflowers, and nanopetals) electrostatically coupled with the gold nanostructures (GNRs and GNSs) to improve their efficiency for photoreduction of CO2 to HCOOH and Suzuki-Miyaura coupling reaction in full-spectrum. The gold nanorods (GNRs) decorated Mn nanopetals (MnNPs@GNRs) showed high efficacy for CO2 reduction to HCOOH with 2.24% of quantum yield and 3.79% of chemical yield in visible light irradiation (6.0 W/cm2) at room temperature. The MnNPs@GNRs exhibited impressive yield for HCOOH formation in NIR and sunlight irradiation too. Likewise, the MnNPs@GNRs showed excellent efficiency for the Suzuki-Miyaura coupling reaction with 99.41% of biphenyl yield in visible light irradiation for 2.0 h at 50 °C. At room temperature (25 °C) the photocatalyst showed 58.71% of biphenyl yield in visible light irradiation. The MnNPs@GNRs exhibited great activity for ten recycles for CO2 conversion as well as coupling reaction without losing activity.

Noble metal loaded ZnCr-LDH based hybrid material for Suzuki coupling reactions: A comparison study on heterogeneous catalysis with photo catalysis

Here, we particularly address the utilization of noble metal loaded LDH based organic–inorganic hybrid materials as heterogeneous catalysts as well as a photo catalyst for sustainable and cleaner organic transformation reactions in fine chemical industries. The highly efficient noble metal nano particles (NPs) like gold (Au) and palladium (Pd) can effectively catalysed the thermal reaction as well as photo catalytic organic reactions. Among the new generation photo catalyst, AuPd alloy loaded LDH (LDH@AuPd) was very much promising material for Suzuki coupling reaction. The Suzuki coupling product (biphenyl) yield was found to be around 98% over the LDH@AuPd composite in photo reaction (time = 2 h at room temp), where as biphenyl yield was around 96% over LDH@Pd NCs in case of thermal reaction (time = 10 h at 80°C). The combined effects of the bimetallic AuPd alloy-based nano composite provide a novel platform for excellent photo catalytic activity towards the Suzuki coupling reactions. So, major consideration should be given to photo catalysts by means of the prospective to be stimulated by the visible light, so as to get cost effectiveness of the photo catalytic organic synthesis. This functionalised photo catalysts can be reused multiple times and recovered merely without considerable loss in catalytic activity and selectivity, which is an enhanced option for practical purposes.

Promotional effect of Co and Ni on MoO3 catalysts for hydrogenolysis of dibenzofuran to biphenyl under atmospheric hydrogen pressure

Co(Ni)/MoO3 catalysts were prepared, characterized and evaluated for the hydrogenolysis of bio-derived dibenzofuran (DBF), aiming at the understanding of the promoting effect of Co/Ni on MoO3 for high-yield production of aromatic products. All Co(Ni)/MoO3 catalysts selectively cleaved C-O bond, thus effectively transformed DBF to biphenyl (BP) at relatively moderate conditions. The experimental results from varying Mo species by adjusting the reduction temperature of MoO3 together with XPS and in-situ XRD characteristic were evident that Mo5+ species was responsible as the major active specie for the reaction. Promotional effect between Co(Ni) and Mo in Co(Ni)/MoO3 catalysts was observed, resulted from the presence of acidic Co(Ni)MoO4 species and a large number of Mo5+ species both of which were created local to the Co(Ni)-O-Mo interface, as can be characterized by in-situ XRD, XPS, H2-TPR, NH3-TPD, in-situ FT-IR, Raman and TEM. The trend of the initial reaction rate follows: MoO3 (0.18 μmol∙gcat−1∙s−1) < Ni/MoO3 (0.26 μmol∙gcat−1∙s−1) < Co/MoO3 (0.29 μmol∙gcat−1∙s−1), corresponding to the decreasing activation barrier. And the best catalytic activity was observed for the 100% yield of BP over Co/MoO3. A possible mechanism, including Co(Ni) facilitated reduction of Mo6+ to Mo5+ and Co(Ni) enhanced formation of acidic sites, is proposed to be responsible for the high activity in Co(Ni)/MoO3 catalysts.

Influence of the p-hydroxyphenyl/guaiacyl ratio on the biphenyl and β-5 contents in compression wood lignins

Abstract Reaction woods of three softwoods, Pinus merkusii, Cryptomeria japonica and Cedrus deodara, were investigated by alkaline nitrobenzene oxidation (NBO) to characterize the condensed-type structures in compression wood lignins. A novel biphenyl-type NBO product carrying guaiacyl (G)- and p-hydroxyphenyl (H)-units, dehydrovanillin-p-hydroxybenzaldehyde (HG-biphenyl product), was identified using the authentic standard compound. On the basis of the yield of this novel NBO product, as well as those of GG-biphenyl-, β-5-, and uncondensed-type products [e.g. dehydrodivanillin, 5-formylvanillin, vanillin and p-hydroxybenzaldehyde], the compression wood lignins contained more HG-type biphenyl and H-type β-5 structures than the opposite wood lignins. The increase in the condensed-type structure content was largely offset by the decreases in the content of GG-biphenyl and G-type β-5 structures. Consequently, the relative yields of biphenyl, β-5 and uncondensed-type NBO products were very similar between the compression wood and the opposite wood, even though the H-unit having no methoxy group on its aromatic ring can be assumed to have a greater probability to form condensed-type structures during lignin biosynthesis than the G-unit.

Insight into cross-linking reactions induced by carboxylates in direct coal liquefaction using coal-related model compounds and hydrogen transfer calculation

Low-rank coals, preferred feedstocks for direct coal liquefaction (DCL), are rich in ion-exchange metal species which are present in the form of carboxylates. In this work, to better understand the negative effects and mechanisms of ion-exchange metal species on oil yield in DCL, cross-linking reactions which were possibly induced by ion-exchange metal species were investigated by hydrogenation of coal-related model compounds and hydrogen transfer calculation for the first time. The results show that CO and CO2 are main products from thermal decomposition of benzoates, implying that decarboxylation of low-rank coals is active during DCL. Compared with benzoic acid, an obvious change of product distribution during hydrogenation of benzoates is that the total yields of biphenyl, diphenylmethane, and benzophenone (products of cross-linking reactions) increase significantly. Besides, the content of CO2 released from hydrogenation of benzoates is much higher than that from benzoic acid. These phenomena indicate that ion-exchange metal species can accelerate decarboxylation reactions and promote formation of free radicals. In addition, hydrogen transfer calculation further proves that ion-exchange sodium species can affect the formation of free radicals. With the increase of the content of ion-exchange sodium species, more free radicals are generated by decarboxylation reactions and combination among free radicals is enhanced. Eventually, less hydrogen is consumed during DCL, which leads to decrease of oil yield. To conclude, cross-linking reactions can be promoted by ion-exchange metal species through enhancing formation of free radicals.

Alumina as Solid‐State Ligand in Enhancing the Redox Catalytic Property of Iron Oxide Grafted AlSBA‐15 towards Arylation of Arene

Abstract2–8 wt % iron has been grafted over SBA‐15 and 10 wt % alumina grafted SBA‐15 (AlSBA‐15) through selective extraction deposition technique using LaFeO3 as iron precursor in acidic solution. DRS‐UV spectra confirmed the presence of iron as isolated Fe(III), Fe(III)‐clusters and amorphous FeOx oligomers. SEM‐EDX mapping, FT‐IR, XPS, HR‐TEM and 27Al MAS NMR characterisation results confirmed that iron grafted over AlSBA‐15 preferentially reside on the alumina. The donor‐acceptor interaction of grafted iron ions with alumina atoms displaying Lewis acid properties stabilized iron at higher oxidation state Fe(III+δ). This increased the BE of Fe2p electrons (XPS) and shifted the temperature of iron reduction in 2–8 wt %Fe/AlSBA‐15 materials to higher value (600 °C) compared with Fe/SBA‐15 (H2‐TPR). In arylation of benzene, 8 wt %Fe/AlSBA‐15 demonstrated excellent redox catalytic activity with TOF close to homogeneous catalyst and 82 % biphenyl yield. The catalyst demonstrated consistent catalytic performance for 7 cycles.

Extended Stöber method to synthesize core-shell magnetic composite catalyst Fe3O4@C-Pd for Suzuki coupling reactions

Fe3O4@C core-shell microspheres have been synthesized by the carbonization of Fe3O4@resorcinol-formaldehyde which was obtained with an extended Stöber method. Without additional reducing agents, Pd nanoparticles were successfully immobilized in the shell of microspheres during the carbonization. The size of Pd nanoparticles could be controlled from 3 nm to 10 nm through adjusting the carbonization temperature from 350 °C to 550 °C. Fe3O4@C-Pd core-shell catalyst carbonized at 550 °C shows the highest catalytic performance in Suzuki coupling reaction of iodobenzene and phenylboronic acid. The yield of biphenyl could reach 100% in 30 min and kept over 90% even after ten-times recycling. The magnetic composite catalysts possess high saturation magnetization (54.90 emu·g−1) and can be easily recovered by the aid of an external magnetic field.

Production of magnetically recoverable, thermally stable, bio-based catalyst: Remarkable turnover frequency and reusability in Suzuki coupling reaction

In any catalysis system, regeneration of the used catalyst is of great importance to reduce the cost of industrial applications. However, recovery of the used catalyst from the reaction medium is a difficult task and this can hinder regeneration process. Magnetic separation has emerged as an effective tool to overcome the recovery problem. Hence, in this study a magnetically recoverable sporopollenin-based Pd catalyst has been designed and used in synthesis of biaryl compounds via Suzuki coupling reaction. The thermally stable catalyst exhibited excellent catalytic behaviour without giving any by-products. It is noteworthy that despite their low product yield of aryl chlorides in coupling reactions, remarkable product yields which are comparable to those of aryl bromides and iodides were recorded for aryl chlorides. With very low catalyst loading (1×10−3mol%), the catalyst gave TOFs values exceeding one million; i.e., 1.237.500 in very short reaction time. Due to its magnetically separable nature, the catalyst could be recovered from the reaction media easily by increasing the reusability of the catalyst. Even in tenth run biphenyl yield dropped from 99 to 93%.

Mesoporous poly(ionic liquid) supported palladium(II) catalyst for oxidative coupling of benzene under atmospheric oxygen

Multi-functional mesoporous poly(ionic liquid) (MPIL) containing pyridine-based ionic liquid (IL) moieties and adjacent double COOH groups was synthesized through the free radical copolymerization of IL monomer N-propane sulfonate-4-vinylpyridine, maleic anhydride and divinylbenzene. Palladium(II) species were anchored on this MPIL support, affording the first efficient heterogeneous catalyst for the oxidative coupling of benzene to biphenyl under atmospheric oxygen at low temperature. The biphenyl yield of 15.0% (selectivity: 98.5%, turnover number: 62) was even higher than the one over the homogeneous counterpart palladium acetate. The catalyst can be facilely separated and reused. The IL moiety in the polymeric framework endowed the formation of immobilized palladium(II) species with high electrophilicity, which responds to the high performance.

Direct aerobic oxidative homocoupling of benzene to biphenyl over functional porous organic polymer supported atomically dispersed palladium catalyst

Synthesis of biphenyl directly from the oxidative coupling of benzene with O2 as the sole oxident is an atom-efficiency and environmental-friendly route, which is however unattainable as yet due to the most inert nature of sp2 CH bond in benzene ring, especailly for recyclable heterogeneous catalysis. In this work, single atomic dispersed palladium(II)-porous organic polymer (POP) catalyst with a high loading (>2wt%) was constructed by anchoring Pd(II) species on the task-specifically designed POP support tethered with carboxyl acid and sulfonic acid groups. It exhibited efficient activity in the heterogeneous aerobic oxidative coupling of benzene with O2, giving the highest biphenyl yield of 26.1% so far. The high electrophilicity of thus anchored single atomic Pd(II) species is demonstrated, endowing the unprecedentedly maximum turnover number (TON) of 487 and turnover frequency (TOF) of 352h−1 that expletively exceeds 15 and 88 times of previous heterogeneous catalyst. The catalyst can be facilely recycled and reused, and readily extendable to the conversion of other nonactivated arenes into corresponding biaryls. The designing strategy of POP materials developed in the study may provide a platform towards stable single atomic dispersed noble metal species with desirable electrophilicity as efficient catalysts for more sustainable CC formation-involved organic transformations.

Ferrocene catalysed C–H arylation of arenes and reaction mechanism study using cyclic voltammetry

Ferrocene catalysed C–H arylation of benzene using aryldiazonium salt is studied. Yield of biphenyl in this reaction was found to be better than some of the known methods. Aryldiazonium salts with electron withdrawing groups produced excellent yields (upto 85%) in C–H arylation. Applicability of this reaction was studied on several arenes and heteroarene such as benzene, naphthalene, anthracene, pyrene and pyridine. Catalytic role of ferrocene in aryl radical formation was studied by cyclic voltammetry of phenyldiazonium tetrafluoroborate. In presence of ferrocene more radical formation was observed. This reaction model works at ambient temperature and features the use of inexpensive catalyst for the synthesis of biaryl derivatives.

Preparation and characterization of palladium immobilized on silica‐coated Fe3O4 and its catalytic performance for Suzuki reaction under microwave irradiation

Supported palladium catalyst (Pd/Fe3O4@SiO2) was easily prepared by supporting PdCl2 on silica‐coated magnetic nanoparticles Fe3O4 in ethylene glycol. The as‐prepared sample was characterized by infrared spectroscopy (IR), X‐ray diffraction (XRD) and X‐ray photoelectron spectrometer (XPS). The formation of active specie Pd(0) was confirmed by XRD and XPS, and the Pd loading for the fresh and recovered catalyst was determined by atomic absorption spectroscopy (AAS). Pd/Fe3O4@SiO2 was employed for the synthesis of biphenyl derivatives via Suzuki reaction. In terms of the yield of biphenyl, the supported catalyst displayed nearly equal catalytic performance to that of homologous PdCl2 under microwave irradiation for 30 min but higher than that obtained by traditional heating method for 12 h. The catalytic performance of Pd/Fe3O4@SiO2 for Suzuki reactions involving various aryl halides and arylboronic acids were also examined. Impressive yield of biphenyl at 68.2% was obtained even in the presence of unreactive aryl chlorides. Pd/Fe3O4@SiO2 was recovered by a permanent magnet and directly reused in the next run, and no obvious deactivation was observed for up to 6 times. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Highly stable palladium-loaded TiO2 nanotube array electrode for the electrocatalytic hydrodehalogenation of polychlorinated biphenyls

Palladized TiO2 nanotube array electrode was prepared for the electrocatalytic hydrodehalogenation (HDH) of 2,4,5-trichlorobiphenyl (2,4,5-PCB). The TiO2 nanotube array electrode was successfully fabricated by anodic oxidation method, and Pd was loaded onto the TiO2 nanotubes by electrochemical deposition. The morphology and structure of the nanotube array electrodes with and without Pd catalysts were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the diameters and lengths of the TiO2 nanotubes were 30–50 nm and 200–400 nm, respectively. The particle size of the Pd was about 12 nm. Electrocatalytic HDH of 2,4,5-PCB with the Pd/TiO2 nanotube array electrode was performed in H-cell reactor. Under a constant potential of -1.0 V, the HDH efficiency of 2,4,5-PCB was 90% and the biphenyl yield was 83% (15% current efficiency) within 180min at the Pd/TiO2 nanotube array electrode. Compared with the Pd/Ti electrode, the Pd/TiO2 nanotube array electrode exhibited higher HDH efficiency and stability. Additionally, the effect of the primary HDH factors was also investigated.

Activation of Aryl Chlorides in Water under Phase-Transfer Agent-Free and Ligand-Free Suzuki Coupling by Heterogeneous Palladium Supported on Hybrid Mesoporous Carbon

In this study, heterogeneous palladium catalysts supported on ordered mesoporous cobalt oxide–carbon nanocomposites were applied to the water-mediated Suzuki coupling reaction of chlorobenzene and phenylboronic acid and exhibited a high yield of biphenyl (49%) under mild reaction conditions free of phase-transfer agents and ligands. Product yields in the reaction of aryl chlorides containing electron-withdrawing groups attached to their benzene ring can reach approximately 90%. Thiol-functionalized mesoporous silica, which can trap soluble Pd species, was used to confirm the negligible leaching in solution and therefore heterogeneous reaction. This heterogeneous catalyst is stable, showing unobvious activity loss after 10 catalytic runs. Characterization by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption fine structure analysis, and N2 sorption techniques revealed intercalated CoO nanoparticles inside a carbon matrix with uniform mesopore sizes (∼3 n...

Pd(0) Nanoparticles Supported Organofunctionalized Clay Driving C–C Coupling Reactions under Benign Conditions through a Pd(0)/Pd(II) Redox Interplay

This work describes the grafting of montmorillonite clay with two organic moieties containing amine and phenyl groups, followed by Pd(0) metal nanoparticle loading, which acted as the active center toward the C–C coupling reactions, through a Pd(0)/Pd(II) redox interplay under benign conditions. Various characterization techniques revealed that the functional groups get strongly attached to the clay surface through its surface hydroxyl groups via covalent bond and 3–5 nm sized Pd(0) nanoparticles get uniformly decorated and stabilized through the organic amine moieties. The catalyst gave 97 and 96% biphenyl yield in Suzuki–Miyaura and Ullmann coupling reactions, respectively, without evidence of leached Pd in five to six runs. After this the catalytic activity decreased, but not to a marginal extent. This could be ascribed to a homogeneous catalytic process following a “release and catch” mechanism resulting in the agglomeration of Pd particles as evidenced from the TEM (transmission electron microscopy) analysis of the eight times recycled catalyst.

Keggin type mono Ni(ii)-substituted phosphomolybdate: a sustainable, homogeneous and reusable catalyst for Suzuki–Miyaura cross-coupling

Keggin type mono Ni(II)-substituted phosphomolybdate was synthesized and characterized by various physico-chemical techniques and used as a catalyst for Suzuki-Miyaura cross-coupling. The influence of different reaction parameters was studied, to get the maximum yield. The novelty of the present work lies in obtaining >97% yield of biphenyl in 14 h under mild reaction conditions. Although the present catalyst is homogeneous, it was regenerated and reused up to two cycles. Results demonstrated that the catalyst was effective and sustainable for cross-coupling of various halobenzenes with phenylboronic acid in aqueous medium.

Using glucosamine as a reductant to prepare reduced graphene oxide and its nanocomposites with metal nanoparticles

A green and facile approach of producing reduced graphene oxide (RGO) by the reduction of graphene oxide (GO) with a monosaccharide medicine glucosamine (GL) was developed. The effect of several factors on the GO reduction, including pH, the weight ratio of GL/GO, and the reaction temperature was studied. The deoxygenation process was monitored with UV–Vis absorption spectroscopy, and the reducing degree of GO was determined with X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Au nanoparticles (about 3.3–4.2 nm) (AuNPs)/RGO and Ag nanoparticles (about 6 nm) (AgNPs)/RGO materials were prepared in two different ways using the above reduction method. They were then used to catalyze the Suzuki–Miyaura coupling reaction of phenyl halide and phenylboronic acid to produce biphenyl, and the highest yield of biphenyl for AuNPs/RGO was 99 %. In addition, the AgNPs/RGO materials exhibited a surface-enhanced Raman scattering effect, and some RGO peaks were enhanced. This approach opens up a new, practical, and green reducing method to prepare RGO for large-scale practical application.