102-09-0Relevant articles and documents
Direct synthesis of diphenyl carbonate from phenol and carbon dioxide over Ti-salen-based catalysts
Kang, Ki Hyuk,Jun, Jin Oh,Han, Seung Ju,Kwon, Kihyeok,Kwon, O-Sung,Jang, Boknam,Song, In Kyu
, p. 8353 - 8358 (2015)
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.
Ti functionalized hierarchical-pore UiO-66(Zr/Ti) catalyst for the transesterification of phenyl acetate and dimethyl carbonate
Jia, Bingying,Wu, Miaojiang,Zhang, Hua,Zeng, Yi,Wang, Gongying
, p. 16981 - 16989 (2019)
Titanates are frequently used as precursors to prepare transesterification catalysts with TiIV species. Unfortunately, it is challenging to control the dispersity of TiIV active sites on supports. Herein, a series of TiIV species is anchored on abundant linker vacancy sites by introducing point and large scale defects in UiO-66(Zr/Ti) with hierarchical-pore structure. The catalyst functionalized by titanium(iv) oxide bis(2,4-pentanedionate) shows excellent catalytic performance in the transesterification of dimethyl carbonate with phenyl acetate. The catalysts are characterized by XRD, FT-IR, N2 adsorption-desorption, XPS, SEM and STEM-HAADF techniques. The results demonstrate that the delicate mesopores in the support can not only exhibit a large surface area for the distribution of the active sites, but also provide better mass transfer performance. Meanwhile, the introduction of octahedral TiIV ions raises the activity of the catalyst via more coordinatively unsaturated ZrIV sites. Furthermore, using titanium(iv) oxide bis(2,4-pentanedionate) as a Ti source can effectively prevent the condensation of tetrahedral TiIV species anchored on the hierarchical-pore UiO-66(Zr/Ti) support.
Gas phase transesterification of dimethylcarbonate and phenol over supported titanium dioxide
Kim, Won Bae,Lee, Jae Sung
, p. 307 - 313 (1999)
The transesterification of dimethylcarbonate and phenol has been studied in a continuous gas flow reactor at high temperatures which were found to be favorable thermodynamically for high yields of methylphenylcarbonate (MPC). Among various solid catalysts, TiO2/SiO2 showed the highest activity and selectivity for MPC. The structure and the chemical state of titanium species in TiO2/SiO2 have been investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near edge structure (XANES) of Ti K-edge. It was observed that the titanium species was highly dispersed on silica. Below 10 wt%Ti loading, the titanium phase was not observed by XRD, yet weak XRD peaks of anatase were detected at higher loadings. The Ti K-edge XANES spectra and XPS analyses indicated that Ti(IV) species in the form of a monolayer was dominant below 5 wt% Ti loadings and TiO2 of the anatase structure appeared at higher loadings. The amount of the surface Ti(IV) species measured by XPS increased with Ti loadings and was saturated above 10 wt% in the same manner as the selectivity to MPC changed with Ti loadings. This suggested that surface Ti(IV) species was directly responsible for the selective synthesis of MPC. The crystalline anatase TiO2 was also an active and selective catalyst for the transesterification, yet it contributed to decrease in activity by coking.
Electrosynthesis of diphenyl carbonate catalyzed by Pd2+/0 (in situ NHC) redox catalyst promoted at Au anode
Kanega, Ryoichi,Ogihara, Hitoshi,Yamanaka, Ichiro
, p. 9497 - 9508 (2015)
The effects of Au anodes on electrochemical carbonylation of phenol with CO (1 atm) to diphenyl carbonate (DPC) catalyzed by Pd (in situ NHC) electrocatalyst were studied under galvanostatic electrolysis conditions. Au supported on carbon materials (Au/carbon) were effective anodes for oxidation of the homogeneous Pd electrocatalyst. Various carbon materials, Vulcan XC-72 carbon black (XC72), activate carbon, Ketjenblack, and graphene nanoplatelets (graphene- 1, -2, -3) were tested as a support for Au. The Au/graphene-3 was the most effective anode for DPC formation. Effects of Au loadings and reducing agents (H2 and NaBH4) on the reactivity of the Au/graphene-3 anode for the DPC formation were studied and the materials were characterized using XRD spectroscopy and TEM analysis. These experimental facts indicated that small Au particles on the surface of graphene were superior for the DPC synthesis by the Pd (in situ NHC) electrocatalyst.
Nuclear Magnetic Resonance Studies of Iminium Salts. Part 11. Anionic Paticipation of Iminium Salts in Phosgenation Reactions
Gauvreau, Jean R.,Martin, Gerard J.,Malfroot, Thierry,Senet, Jean Pierre
, p. 1971 - 1974 (1984)
Iminium salts act as catalysts in the reaction of phosgene and phenols or thiols to yield chloroformates, which are important synthetic intermediates.This effect is explained in terms of the nucleophilicity of the chloride anion of the salts on the basis of an n.m.r. identification of various intermediates.The mechanism of nucleophilic assistance of iminium salts towards the substrate can be understood as an increase of the nucleophilicity of phenol or thiol by proton abstraction from the OH or SH group by the chloride anion.
Highly efficient and stable PbO-ZrO2 catalyst for the disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate
Wang, Songlin,Li, Changgong,Xiao, Zhongliang,Chen, Tong,Wang, Gongying
, p. 26 - 33 (2016)
Heterogeneous PbO-ZrO2 catalysts (PbZr) were first prepared by coprecipitation method, and used to catalyze the liquid-phase disproportionation reaction of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC). PbZr with PbO loading of 15.2 wt% (15.2PbZr) exhibited the best catalytic performance. Under the optimal conditions (200 °C, 2.5 h, and 1.2 g catalyst), the conversion of MPC reached 76.6% and the selectivity of DPC was 99.3%, respectively, which were significantly higher than those of heterogeneous catalysts reported before. The characterization results of XPS, H2-TPR, XRD and BET analyses showed that 15.2PbZr gave the strongest interaction between Pb and Zr, the highest dispersion of PbO as well as the largest surface area and pore volume. Moreover, for 15.2PbZr, though reused for five recycles, the conversion of MPC still reached 75% and the selectivity of DPC was kept at 99.0%, implying that 15.2PbZr represented superior reusability. Besides, the structure of the 15.2PbZr after five times reaction was almost identical to that of the fresh, and Pb was almost not leached out of the catalyst, indicating that the stability of Pb species was improved, due to the existence of favorable interaction between Pb and Zr as well as part of the Pb entering into ZrO2 structure. Thus, 15.2PbZr may serve as a promising catalyst for MPC disproportionation.
The mechanic study of the Pd-catalyzed synthesis of diphenylcarbonate with heteropolyacid as a cocatalyst
Hatanaka, Itsuhiro,Mitsuyasu, Naho,Yin, Guochuan,Fujiwara, Yuzo,Kitamura, Tsugio,Kusakabe, Katsumi,Yamaji, Teizo
, p. 96 - 100 (2003)
The reaction to synthesize diphenyl carbonate (DPC) by an oxidative carbonylation of phenol with CO and O2 has been found to proceed through the second-order of phenol concentration. The activation energy E a, Δ S and Δ H are 27.0 kcal mol-1, -6.43 cal mol-1 and 26.3 kcal mol-1, respectively. The kinetic and additive data obtained agree with the proposed mechanism as follows: Pd(OAc)2 reacts with an ammonium phenoxy salt to give AcO-Pd-OPh which then reacts with CO to form AcO-Pd-COOPh. This species leads to PhO-Pd-COOPh which undergoes reductive elimination to give DPC and Pd(0). This Pd(0) is reoxidized to Pd(II) by the help of a heteropolyacid very effectively.
Tellurobromic Acid Diesters; Preparation and Properties
Suzuki, Hitomi,Nishioka, Yoshinobu
, p. 2117 - 2118 (1989)
Title compounds were obtained as reasonably stable to labile oily substances by reacting alkyl carbonochloridates with sodium telluride under phase-transfer conditions at room temperature or in dry n,n-dimethylformamide under ice-cooling.
Mesoporous silica-anchored organotin as heterogeneous catalyst for the transesterification of dimethyl carbonate with phenol
Zhang, Yuanzhuo,Wang, Songlin,Xiao, Zhongliang,Chen, Tong,Wang, Gongying
, p. 7213 - 7222 (2016)
A simple scheme for a mesoporous silica-anchored organotin catalyst was developed for the transesterification of dimethyl carbonate with phenol to diphenyl carbonate. N2-sorption, TEM, UV–Vis, and elemental analysis combined with 29Si and 13C NMR measurements evidenced the formation of mesoporous organic–inorganic hybrid silica with a highly dispersed tetrahedral Sn species. The catalyst exhibited excellent activity and reusability in the transesterification. With a catalyst of 1.0?g, a reaction temperature of 150–180?°C, and a reaction time of 9?h, the phenol conversion and transesterification selectivity reached 51.1 and 99.9?%, respectively. The phenol conversion just decreased from 41.2 to 35.0?% after five runs with 0.5?g of catalyst. The improved stability was attributed to the strong covalent bonding between the organotin and mesoporous silica.
Highly effective transformation of methyl phenyl carbonate to diphenyl carbonate with recyclable Pb nanocatalyst
Wang, Songlin,Niu, Hongying,Wang, Jianji,Chen, Tong,Wang, Gongying,Zhang, Jiamin
, p. 20415 - 20423 (2019)
Diphenyl carbonate (DPC) is a type of versatile industrial chemical, and the disproportionation of methyl phenyl carbonate (MPC) is a key step to produce DPC. However, the design and formulation of a catalyst for the efficient synthesis of DPC is a major challenge due to its small equilibrium constant. The support material is a critical factor influencing the performance of Pb nanocatalysts. Thus, a series of Pb-based catalysts over MgO, ZrO2, SiO2, TiO2 and Al2O3 were prepared to investigate the effect of the support materials on the physicochemical properties and catalytic performances for the conversion of MPC to effectively synthesize DPC. The catalysts were well characterized by XRD, BET, TEM, XPS, ICP-OES, H2-TPR, Py-IR and NH3-TPD. The results showed that the nature of the support obviously affected the structural properties and catalytic performances, and Pb was dispersed better on SiO2, TiO2, ZrO2 and MgO than on Al2O3, and showed stronger metal-support interaction over MgO and ZrO2. The activity results revealed that PbO/MgO and PbO/ZrO2 exhibited higher catalytic activities because they contained higher Pb dispersion and more Lewis acid sites, and the catalytic activities followed the order PbO/MgO > PbO/ZrO2 > PbO/SiO2 > PbO/Al2O3 > PbO/TiO2. On the contrary, PbO/MgO and PbO/ZrO2 exhibited better reusability due to strong interaction between the highly dispersed Pb and the supports, and the activity decrease in the case of PbO/SiO2, PbO/Al2O3 and PbO/TiO2 mainly resulted from the Pb leaching loss. This work would contribute to exploiting novel catalytic materials in a wide range of applications for the efficient synthesis of organic carbonates.
