Direct Synthesis Of Diphenyl Carbonate Research Articles

Direct Synthesis of Diphenyl Carbonate from Phenol and Carbon Dioxide Over Ti-Salen-Based Catalysts.

Various metal-salen catalysts were prepared for use in the direct synthesis of diphenyl carbonate (DPC) from phenol and carbon dioxide. We found that metal-salen complexes containing titanium as central metal species retained suitable Lewis acid property for the reaction. It was revealed that the catalytic activity of Ti-salen complexes could be controlled by introducing appropriate substituents into salen ligand. Insertion of phosphonium salts into para-position of aromatic aldehyde of salen ligand enhanced solubility of the catalyst in the methanol-phenol solution, and tert-butyl substituent in the salen ligand induced selective formation of DPC due to steric effect. In addition, introduction of various bridging groups into salen ligand caused change in electronic property of central metal atom. Among the catalysts tested, Ti-(t-butyl)salphen(PPh3)Cl showed the best catalytic performance at 100 °C and 60 bar. The catalytic system utilizing Ti-(t-butyl)salphen(PPh3)Cl catalyst was then optimized by conducting the reaction at various reaction temperatures and pressures.

Solid–liquid equilibria and the physical properties of binary systems of diphenyl carbonate, dimethyl carbonate, methyl phenyl carbonate, anisole, methanol and phenol

Non-phosgene diphenyl carbonate (DPC) can be synthesized via many routes. A preferable green route of synthesis consists of a two-step reaction from dimethyl carbonate (DMC) and phenol because the direct synthesis of DPC is limited due to the low equilibrium constants of the forward reaction. In this synthesis process, the reaction products with intermediates should be separated from each other for higher yields of DPC and to recycle the reactants. However, relatively few studies have examined the separation design properties, particularly, the phase equilibria and the physical properties for systems containing the reaction intermediate methyl phenyl carbonate (MPC). In the present work, we analytically determined the binary solid–liquid equilibria (SLE) for the {DMC (1)+DPC (2)}, {DPC (1)+MPC (2)}, {phenol (1)+MPC (2)} and {methanol (1)+DPC (2)} systems. The former three systems showed a simple eutectic point, while the {methanol (1)+DPC (2)} system did not. The determined SLE data correlated well with a non-random two-liquid (NRTL) activity coefficient model. In addition, the temperature dependence of the physical properties of the reaction products densities, refractive indices and kinematic viscosities were reported. The experimental properties were correlated well with the Daubert and Danner (DIPPR) equation for density, the linear equation for refractive index, and the Goletz and Tassion equation for kinematic viscosity, respectively.

Synthesis of Diphenyl Carbonate from Carbon Dioxide Catalyzed by ZnCl<sub>2</sub> Supported on SiO<sub>2</sub>-TiO<sub>2</sub>

SiO2-TiO2 mixed oxides was prepared by the homogeneous precipitation method using tetraethoxysilane and tetrabutyl titanate as precursors. Zinc catalyst supported on SiO2-TiO2 was prepared by the incipient wetness impregnation method and employed as effective catalyst for the direct synthesis of diphenyl carbonate from carbon dioxide and phenol. The stability of the heterogeneous catalyst was also studied in detail. No significant loss of activity was observed during the 5 runs except for the first recycle.

First Principle Investigation of O<sub>2</sub> Adsorption on the LaMnO<sub>3</sub> (001) Surface

The first-principle method based on the pseudopotential plane-wave is adopted to analyze O2 adsorption on the LaMnO3 (001) surface. The calculated results indicate that, LaMnO3 presents half-metal properties by calculating the band structure and density of states (DOS). In the MnO6 octahedron, the O-Mn-O bond is mainly covalent, on the contrast, O-La-O bond is mainly ionic. Molecular oxygen can adsorb on the LaMnO3 (001), M2 may be the most favourable adsorption mode. The adsorption mode leads to the formation of .The valence of Mn in the adsorption sites after adsorption of M1 and M2 is Mn3+0.25, Mn3+0.31, respectively. M2 may be the most adsorption mode that can make Pd 0 to shift Pd2+ more quickly in the process of direct synthesis of diphenyl carbonate (DPC) using the catalyst -Pd supported on the LaMnO3.

Direct synthesis of diphenyl carbonate by mediated electrocarbonylation of phenol at Pd2+-supported activated carbon anode

Mediated electrocarbonylation of phenol to diphenyl carbonate (DPC) at a PdCl2-supported activated carbon anode in 1atm CO at 298K was studied. A dry CH2Cl2 or CH3CN solvent and a galvanostatic electrolysis of 1mA were necessary for formation of DPC, while the addition of a base and a supporting electrolyte was also essential. A combination of triethylamine (Et3N) and tetrabutylammonium perchlorate (Bu4NClO4) was suitable in various combinations. The addition of 2 equiv. of Et3N to the electrolyte (C6H5OH/Bu4NClO4/CH2Cl2) at 1-h intervals was more efficient in the formation of DPC than a single initial addition of the same amount of Et3N. The yield of DPC was 130% based on Pd and its current efficiency (CE) was 42% for 6h. The CE of the CO2 formation was only 3%. Sodium phenoxide (PhONa) showed dual functionality as a base and supporting electrolyte. When the mediated electrocarbonylation was conducted in a C6H5OH/PhONa/CH3CN electrolyte, DPC was produced in 172% yield and 40% CE for 6h. The CE of the CO2 formation was 10%. DPC formed continuously after a single initial addition of 4 equiv. of PhONa. Li or K phenoxide also worked as promoters for the mediated electrocarbonylation of phenol to DPC.

A novel method to synthesize diphenyl carbonate from carbon dioxide and phenol in the presence of methanol

A novel method for the direct synthesis of diphenyl carbonate (DPC) from carbon dioxide and phenol catalyzed by Lewis acid in the presence of methanol was developed. It was found that the simple Lewis acids are not effective for catalyzing the production of DPC, but (salen)Co(OAc) containing a quaternary phosphonium salt unit anchored on the ligand displayed excellent catalytic activity under mild conditions using dense carbon dioxide as reactant and solvent. A possible mechanism for the formation of DPC was proposed based on the GC-MS analysis and DFT calculation.

Direct Synthesis of Diphenyl Carbonate by Electrocarbonylation at a Pd2+-supported Anode

Abstract The first electrochemical synthesis of diphenyl carbonate was accomplished using triethylamine/tetrabutylammonium perchlorate/phenol/dichloromethane or sodium phenoxide/phenol/acetonitrile electrolyte at a [PdCl2/activated carbon and vapor grown carbon fiber] anode, 1 atm CO and 25 °C. Sodium phenoxide functioned as a promoter, triethylamine, and a supporting electrolyte, tetrabutylammonium perchlorate, for the carbonylation.

Synthesis of Pd(C 4H 2O 4)(C 4H 8N 2) 0.5 Complex and the Catalytic Activity for Oxidative Carbonylation of Phenol

A novel complex Pd(C 4H 2O 4)(C 4H 8N 2) 0.5 has been synthesized by solvent thermal synthesis and used as a heterogeneous catalyst for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol. In the reaction system of Pd(C 4H 2O 4)(C 4H 8N 2) 0.5/Cu(OAc) 2/tetrabutylammonium bromide/hydroquinone/4A molecular sieves, the effect of reaction temperature, time and CO pressure on catalytic activity were investigated, and the results revealed that the catalyst could catalyze oxidative carbonylation of phenol effectively. Under suitable reaction conditions of T=90°C, t=4 h, p(O 2)=0.3 MPa, p(CO)=3.9 MPa and CH 2Cl 2 as solvent, the turnover number (TON) of diphenyl carbonate can reach about 13.50 (mol-DPC/mol-Pd), which is higher than the TON for pure PdCl 2 under the same reaction conditions.

Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalyst and Optimal Synthesis Conditions of the Support Prepared by Sol-gel Method

The support of catalyst for the direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction was prepared by the sol-gel method. Compared with activated charcoal, molecular sieve, porous ceramics, hopcalite, the support prepared by the sol-gel method has higher activity. The characterization of the support by X-ray diffraction (XRD) and transmission electron microscope (TEM) show that the main crystal phase is Co 2MnO 4 and the average particle diameter is about 40 nm. The optimum conditions for synthesis of the support were determined by orthogonal experiments, which indicate that the proportion of Cu, Mn, and Co is the first important factor influencing the yield and selectivity of DPC. Temperature of calcination is the second one. The optimum conditions are: molar proportion of Cu, Mn, and Co being 1:1:1, temperature of calcination 700°C, drying at 100°C, temperature of water bath 85°C. The yield and selectivity of DPC in the process can reach 38% and 99% in the batch operation, respectively. The copper cobalt manganese mixed oxides chosen as the support contribute more to the high catalytic activity than the sol-gel method.

Direct synthesis of diphenyl carbonate over heterogeneous catalyst: effects of structure of substituted perovskite carrier on the catalyst activities

The perovskite-type compound LaMnO3 was substituted for the part of La in position A and for the part of Mn in position B by citrate method. The phases were detected by X-ray diffraction. Powder morphologies were scanned by scanning electron microscopy. The valence of atoms was determined by X-ray photoelectron spectroscopy. It was found that the perovskite can form crystal defect and increase the proportion of high valence B element by doping. Active component Pd was loaded on various perovskite supports for synthesis of diphenyl carbonate. The results showed that the activities of catalysts in which supports have crystal defect by substitution were higher. It can be concluded that perovskite with defect structure by doping could lead to the formation of oxygen vacancy where the lattice oxygen became exchangeable with the oxygen gas. Also, this improved the redox process of the carrier by transferring electrons and activities of catalysts.

Synthesis of Diphenyl Carbonate from CO2, Phenoxide, and CCl4 with ZnCl2 as Catalyst

Abstract Direct synthesis of diphenyl carbonate (DPC) from phenoxide, CO2 and CCl4 in one pot was realized with ZnCl2 as catalyst. Trichloromethyl cation may act on potassium phenyl carbonate, which brings the carbonyl more easily attached on by the phenoxide. Onium salts promote the reaction greatly, especially with phenol and potassium carbonate instead of phenoxide as reactants. Moreover, the substituent on the aromatic ring has significant effects on the selectivity and yield of carbonate.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by ultrafine embedded catalyst Pd–Cu–O/SiO 2

An ultrafine embedded catalyst Pd–Cu–O/SiO 2 was prepared in a water-in-oil (W/O) microemulsion for the direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol with carbon monoxide and oxygen. In this catalyst, there are palladium–copper oxide cores surrounded by the silica shell, which provides protection for the active constituents during the reaction. This can reduce the leaching of the active components and then prolong the catalysts’ service time. The embedded catalyst shows higher activity than the catalyst prepared by sol–gel process and longer service time than the catalyst prepared by impregnation method. The turnover number reached about 117.50 (mol-DPC/mol-Pd) at certain conditions. But the leaching of Pd and Cu in the embedded catalyst is still serious for some of them are located on the surface of the silica supports and easily enter into the solvent.

An environmentally benign process for aromatic polycarbonate synthesis by efficient oxidative carbonylation catalyzed by Pd-carbene complexes

The direct synthesis of diphenyl carbonate (DPC) and polycarbonate (PC) by oxidative carbonylation was investigated. A palladium catalyst anchored to a resin via a heterocyclic carbene ligand exhibited high performance in DPC synthesis, and the total turnover number (TON) achieved 5100 (mol-DPC/mol-Pd). Bisphenol A was also effectively converted to high molecular weight PC (Mw 22,400) at 95% yield.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd–pyridyl complexes tethered on polymer support

Various Pd–pyridyl complexes tethered on polystyrene were investigated as novel immobilized Pd catalysts for the direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation using phenol, carbon monoxide, and air. These Pd catalysts showed reasonably high efficiencies in the absence of ammonium halide. The best efficiencies were obtained by using Pd–biquinoline complex tethered on polystyrene 1, Pd–bipyridyl complex tethered on polystyrene 3, and Pd–methylpyridyl complex tethered on polystyrene 7 where TOF reached about 4 (mol-DPC/mol-Pd h), respectively. Their efficiencies were higher than those of the Pd complex catalyst tethered on conventional polymer support and PdBr 2 under similar conditions.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by bis(benzonitrile)dichloropalladium in the presence of polyvinylpyrrolidone

Pd(PhCN) 2Cl 2 [bis(benzonitrile)dichloropalladium] were investigated in the presence of polyvinylpyrrolidone (PVP) as a polymer support for the direct synthesis of diphenyl carbonate (DPC) by the oxidative carbonylation of phenol using carbon monoxide (CO) and air. Pd(PhCN) 2Cl 2 was found to be more efficient than the conventional PdBr 2 system, and its efficiency was accelerated in the presence of high molecular weight PVP with M w=360,000 and 1,300,000. The best efficiency of Pd(PhCN) 2Cl 2/Mn(TMHD) 3 [tris(2,2,6,6-tetramethyl-3,5-heptanedionato)manganese]/(Ph 3P) 2NBr [bis(triphenylphosphoranylidene)ammonium bromide] system was obtained by using 0.241 mmol of PVP with M w=360,000 where TOF (turnover frequency) reached 11.31 (mol-DPC/mol-Pd h, Pd/Mn/Br/phenol=1/2/20/2667; CO 0.50 MPa; air 0.25 MPa, 100°C, 3 h).

酸化的カルボニル化反応による芳香族カーボネートの合成 高活性パラジウム錯体触媒系の開発とポリカーボネート一段合成への応用

New catalyst systems for the direct synthesis of diphenyl carbonate (DPC) from carbon monoxide (CO) and phenol were investigated. Palladium-tin complexes [Pd2(dPPm)2(SnCl3) Cl and Pd2(dppm)2(SnCl3)2, dppm : bis (diphenylphospino) methane] with manganese redox catalyst [Mn(TMHD)3, TMHD : 2, 2, 6, 6-tetramethyl-3, 5-heptanedionate] were found to produce DPC effectively without any addition of ammonium halide. Furthermore, palladium catalyst systems such as, palladium dinuclear complexes, palladium-diimine complexes, and palladium-6, 6'-disubstituted-2, 2'-bipyridyl complexes promoted the oxidative carbonylation of phenol more effectively in the presence of ammonium halide. Especially, the efficiencies of Pd2(Ph2PPY)2(NO2)2(Ph2PPy : 2-pyridyldiphenylphosphine) and Pd(6, 6'-Me2bpy)Cl2(6, 6'-Me2bpy : 6, 6'-dimethyl-2, 2'-bipyridyl) were highest among these palladium complexes. These palladium catalyst systems were applied for the direct synthesis of polycarbonate (PC) from bisphenol A and CO. PC with the number-and weight-average molecular weights of 5600 and 12900 respectively, was successfully obtained using Pd (6, 6'-Me2bpy) Cl2 catalyst system. These molecular weights were highest among the direct syntheses of PC by oxidative carbonylation.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd complex with 2,2′-bipyridyl ligands

Pd–2,2′-bipyridyl complexes were investigated as novel Pd catalysts for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol using carbon monoxide (CO) and air. Pd–2,2′-bipyridyl complexes which possess a pair of substituents at 6,6′-position of 2,2′-bipyridyl moiety were found to be more effective than Pd–2,2′-bipyridyl complexes without any substituents at the 6,6′-position. The best efficiency was obtained by using PdCl 2(6,6′-Me 2bpy) (6,6′-Me 2bpy: 6,6′-dimethyl–2,2′-bipyridyl)/Mn(TMHD) 3 (TMHD: 2,2,6,6-tetramethyl–3,5-heptandionate)/(Ph 3P) 2NBr [bis(triphenylphosphoranylidene)ammonium bromide] system where TOF reached 13.17 (mol-DPC/mol-Pd h). The efficiency of our PdCl 2(6,6′-Me 2bpy)/Mn(TMHD) 3/(Ph 3P) 2NBr system was higher than that of conventional PdBr 2/Ce(Trop) 4 (Trop: tropolonate)/(Ph 3P) 2NBr system.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd complex with diimine ligands

Pd complexes with diimine ligands were investigated as novel Pd catalysts for direct synthesis of diphenyl carbonate by oxidative carbonylation of phenol using carbon monoxide and air. Best efficiency was obtained by using a PdCl2(ArN=CH–)2 or PdCl2(ArN=CMe–)2/Mn(TMHD)3/(Ph3P=)2NBr system where TOF reached 8.08 and 8.00 mol-DPC/mol-Pd h, respectively. The efficiency was increased with increases in the CO pressure.

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd dinuclear complex bridged with pyridylphosphine ligand

Pd dinuclear complexes bridged with pyridylphosphine ligand such as Pd2(Ph2PPy)2X2 (Ph2PPy: diphenyl-2-pyridylphosphine, X: Cl, Br, I, OCN, SCN, NO2, N3) were investigated as catalysts for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol using carbon monoxide (CO) and air. Pd2(Ph2PPy)2X2/redox catalyst/ammonium halide system were found to be more effective than not only conventional PdBr2/Ce(Trop)4 (Trop: tropolonate)/(Ph3P=)2NBr (bis(triphenylphosphoranylidene)ammonium bromide) system but Pd2(dpm)2X2 (dpm: bis(diphenylphosphino)methane)/Mn(TMHD)3 (TMHD: 2,2,6,6-tetramethyl-3,5-hepentanedionate)/(Ph3P=)2NBr system too. The best efficiency was obtained by using Pd2(Ph2PPy)2(NO2)2/Ce(TMHD)4/(Ph3P=)2NBr system where TOF reached 19.21 (mol-DPC/mol-Pd h).

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd dinuclear complex

Pd dinuclear complexes were investigated as catalysts for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol using carbon monoxide and air. Pd dinuclear complexes such as Pd 2(dpm) 2X 2 [dpm: bis(diphenylphosphino)methane, X: Cl, Br, I, OCN, SCN, N 2O, N 3] were found to be novel catalysts for the oxidative carbonylation of phenol. Pd 2(dpm) 2(OCN) 2/Mn(TMHD) 3/(Ph 3P) 2NBr system was more effective than conventional Pd mononuclear catalyst.