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.

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.

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.

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.

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.

Photo-deposition preparation of supported Pd catalysts for non-phosgene one-step synthesis of diphenyl carbonate

Wu, Changjiang,Yang, Xiaojun,Tian, Qifeng,Bai, Hang,Li, Xiaolu

, p. 106 - 110 (2019)

Pd catalysts anchored on manganese oxide octahedral molecular sieves (OMS-2) were synthesized by photo-deposition method, and then used for one-step oxidative carbonylation of phenol to synthesize diphenyl carbonate (DPC). The results showed that the catalytic activity of Pd/OMS-2 catalyst prepared by photo-deposition was apparently better than those prepared by the traditional precipitation and impregnation method, the distribution of Pd particles was more uniform with the average size of 1.3 nm. This may result from the strong interaction between the carriers and the active Pd species. Irradiated for 5 h at pH 5.0, with the Pd loading of 2.5 wt%, the highest DPC yield of 18.1% was achieved.

Catalytic performance of metal oxide modified SiMcM-41 catalysts in diphenyl carbonate synthesis

Su,Li,Cheng,Ren,Yu,Wang

, p. 359 - 363 (2010)

Decomposition of CCl4 into diphenyl carbonate (DPC) was examined over metal oxides modified SiMCM-41. ZnO/SiMCM-41 and Fe2O 3/SiMCM-41 showed high activity in DPC synthesis. Although many other metal oxides, such as La2O3, CuO, Al2O3 and alkali or alkaline earth oxide, were success in destruction of CCl4, they displayed nearly no activity on DPC synthesis. ZnO/SiMCM-41 and Fe2O3/SiMCM-41 were characterized by X-ray diffraction (XRD), UV-Raman, 29Si MAS NMR and N2 adsorption-desorption isotherms, and results showed that ferric and zinc oxide were supported onto SiMCM-41. The well ZnO dispersion in SiMCM-41 channels and the weak electrostatic interaction between chlorine anion and Zn2+ play an important role for the high activity of ZnO/SiMCM-41 in decomposition of CCl4 into DPC. Pleiades Publishing, Ltd., 2010.

Oxidative carbonylation of phenol with a Pd-O/CeO2-nanotube catalyst

Yuan, Ye,Wang, Zhimiao,An, Hualiang,Xue, Wei,Wang, Yanji

, p. 1142 - 1154 (2015)

CeO2 nanotubes (CeO2-NT) were synthesized using carbon nanotubes as template by a liquid phase deposition and hydrothermal method. X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption were used to characterize the CeO2-NT. The wall of CeO2-NT was composed of small interconnected nanocrystallites ranging from 4 to 9 nm in size. The specific surface area of CeO2-NT was 108.8 m2/g with an outer diameter of 25 nm and length > 300 nm. Supported Pd catalyst, Pd-O/CeO2-NT, was prepared using CeO2-NT as the support. Temperature-programmed reduction analysis showed that the surface oxygen on Pd-O/CeO2-NT could be reduced at low temperature, therefore it showed high activity in the reaction. Pd-O/CeO2-NT was used as the catalyst for the oxidative carbonylation of phenol. It has better activity and DPC selectivity than Pd-O/CeO2-P, which was prepared by supporting Pd on zero dimensional CeO2 particles. Under the optimized conditions, phenol conversion was 67.7% with 93.3% DPC selectivity with Pd-O/CeO2-NT. However, its catalytic activity decreased when the catalyst was used for the second time. This was attributed to the destruction of the tubular structure of Pd-O/CeO2-NT and Pd leaching during the reaction.

Tuning of oxygen species and active Pd2+ species of supported catalysts via morphology and Mn doping in oxidative carbonylation of phenol

Yang, Xiaojun,Hu, Yue,Bai, Hang,Feng, Maoqi,Yan, Zhiguo,Cao, Shuo,Yang, Bin

, p. 1 - 7 (2018)

A series of nanocubes and nanorods of CeO2 and MnxCeyO (x,y = 1 or 3) oxides were prepared by the hydrothermal method. Samples as prepared were characterized by Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy, in order to gain a fundamental understanding of the effects of the morphology and Mn dopant on the oxygen species and active Pd2+ species in the oxidative carbonylation of phenol using Pd catalysts supported on as-prepared oxides. Although the oxygen species on supports with different morphologies varied, the catalytic performance in the oxidative carbonylation reaction did not show the significant change. Comparatively speaking, the doping of Mn is a more efficient method to control active oxygen species. It is deduced that Pd and Mn are “dopants” for pure CeO2, both of which improve the formation of oxygen vacancies that help to mitigate the reduction of active Pd species due to the strong interaction between the Pd2+ and the MnxCeyO support. Furthermore, we propose that Oβ (hydroxyl oxygen, chemisorbed oxygen or the oxygen vacancy) species acted as intermediates to lower the reduction of active palladium species by the strong interaction between the noble metal and supports, while the lattice oxygen Oα were involved in the redox cycle of Pd0/Pd2+ in the oxidative carbonylation of phenol to diphenyl carbonate. All results suggest that Mn dopants play a more important role in the activity than morphology does.

Transesterification of dimethyl carbonate and phenol to diphenyl carbonate with the bismuth compounds

Xiao, Zhongliang,Yang, Hao,Zhang, Hua,Chen, Tong,Wang, Gongying

, p. 2347 - 2352 (2018)

Bismuth oxide was first employed for the transesterification of dimethyl carbonate with phenol to diphenyl carbonate, which has excellent catalytic activity. With 0.4?g Bi2O3, the phenol conversion of 46.4% and transesterification selectivity of 99.9% were attained. The characterization of the used sample by XRD, FTIR and solid-state 13C-NMR indicate that a new compound of bismuth phenoxide was formed with the disappearance of bismuth oxide. It was evidenced that the bismuth phenoxide act as the role of active phase in the transesterification, which was generated facilely in situ by the reaction of bismuth oxide added with the raw material of phenol. The bismuth phenoxide presents excellent reusability, after four consecutive runs, the phenol conversion remained above 45%, and the transesterification selectivity was maintained at 99.9%.

Direct synthesis of diphenyl carbonate by electrocarbonylation at a Pd 2+-supported anode

Murayama, Toru,Arai, Yuji,Hayashi, Tomohiko,Yamanaka, Ichiro

, p. 418 - 419 (2010)

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.

Deactivation causes of supported palladium catalysts for the oxidative carbonylation of phenol

Yin, Chaofan,Zhou, Jie,Chen, Qiming,Han, Jinyu,Wu, Yuanxin,Yang, Xiaojun

, p. 377 - 383 (2016)

Palladium catalysts supported on manganese oxides octahedral molecular sieves (OMS-2), Pb doped OMS-2 (Pb-OMS-2) and perovskite-type La0.5Pb0.5MnO3 were prepared for investigating the deactivation causes of catalysts during the oxidative carbonylation of phenol. The catalytic experiments on three different sets of catalysts demonstrated that they were inactive after continuous reaction for 22?h. XRD patterns and HRTEM images demonstrated that carbonaceous pollution and palladium leaching occurred during the reaction process. The solvent and oxygen have significant impact on the palladium leaching by ICP-AES analysis. In addition, hot filtration tests and SH-HZSM-5 adsorption studies indicated that the leached palladium species are not active species. The results of XPS patterns and H2-TPR profiles showed that aggregation and reduction of Pd species was another deactivation cause. It was discovered that lattice oxygen species decreased and palladium aggregated, which hindered the re-oxidation of Pd(0) to Pd(II). In summary, carbonaceous pollution, Pd leaching, aggregation and consumption of oxygen species hindered the redox recycling of palladium, which resulted in the deactivation of supported palladium catalysts for the oxidative carbonylation of phenol.

Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6 H)-carboxylates: A practical alternative to chloroformates for the synthesis of symmetric and asymmetric carbonates

Moon, Hyun Kyung,Sung, Gi Hyeon,Yoon, Yong-Jin,Yoon, Hyo Jae

, p. 1577 - 1581 (2016)

Symmetric and asymmetric carbonates were synthesized by using alkyl or aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates. Five aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates were converted into the corresponding diaryl carbonates in good to excellent yields by treatment with potassium carbonate in refluxing THF. When the 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates were treated with aliphatic or aromatic alcohols in the presence of potassium tert-butoxide in toluene at room temperature, they gave the corresponding symmetric or asymmetric carbonates in moderate to excellent yields. Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates are therefore efficient, stable, and ecofriendly alternatives to chloroformates.

Hallgren,Matthews

, p. 135,136, 139 (1979)

THE PALLADIUM-CATALYZED SYNTHESIS OF DIPHENYL CARBONATE FROM PHENOL, CARBON MONOXIDE, AND OXYGEN

Hallgren, J.E.,Lucas, G.M.,Matthews, R.O.

, p. 135 - 138 (1981)

Diphenyl carbonate was obtained from the reaction of carbon monoxide, phenol, and oxygen using catalytic quantities of palladium, a tertiary amine, and an oxidation cocatalyst at room temperature and atmospheric pressure.A variety of copper, vanadium, cobalt, and manganese salts were effective cocatalysts, although in many cases side products were produced.Using catalytic quantities of manganese salts, up to 100 mol of diphenylcarbonate per mol palladium was realized.

Influence of coordination groups on the catalytic performances of organo-titanium compounds for disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate

Wang, Songlin,Chen, Tong,Wang, Gongying,Cui, Chengxing,Niu, Hongying,Li, Changgong

, p. 1 - 6 (2017)

The disproportionation of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC) catalyzed by organo-titanium compounds with different coordination groups was systematically investigated. The results of the molecular structure analysis, the catalytic performance evaluation and the chemical computational studies revealed that both the electron effect and steric hindrance of the coordination groups together affected the active Ti center and therefore influenced the catalytic performance of the catalysts. The influence of the electron effect was more important than the steric hindrance. The catalytic activity is in the order of Ti(O-iC3H7)4?>?Ti(OC6H5)4?>?Ti(OC4H9)4?>?TiO(OOCCH3)2?>?TiO(acac)2?>?Cp2TiCl2, and Ti(O-iC3H7)4 exhibited the best catalytic performance, due to its appropriate steric hindrance and electron effect for the coordination group. Under the optimum condition (n(Cat.)/n(MPC)?=?0.04, reacted at 180?°C for 3?h), the MPC conversion of 90.4% and DPC selectivity of 99.6% were attained, respectively, which are comparable to those of other catalysts reported. Moreover, the catalyst is low cost, non-toxic and easily obtained by readily commercial-available purchase, and this catalytic system is also easy operation and convenient-controllable, indicating that it is conducive to future industrial application. In addition, a possible reaction mechanism catalyzed by the organo-titanium compounds with Lewis acid was also proposed for the process.

Double- and triple-consecutive O-insertion into tert-butyl and triarylmethyl structures

Krasutsky, Pavel A.,Kolomitsyn, Igor V.,Krasutsky, Sergiy G.,Kiprof, Paul

, p. 2539 - 2542 (2004)

(Matrix Presented) The concecutive Criegee rearrangement reactions were studied for tert-butyl trifluoroacetate, triarylcarbinols, and benzophenone ketales with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFA). The formation of methyl acetate and methyl trifluoroacetate indicates that the consecutive double-O-insertion process has taken place for tert-butyl trifluoroacetate. The intermediate dimethoxymethylcarbonium ion was detected below 5°C. A consecutive triple-O-insertion process has been observed for triarylmethanols and benzophenone ketals. A new high yield method of corresponding diaryl carbonates synthesis was developed.

Preparation and catalytic property of Pb-Zr mixed oxides for methyl phenyl carbonate disproportionation to synthesize diphenyl carbonate

Wang, Songlin,Niu, Hongying,Wang, Jianji,Chen, Tong,Wang, Gongying

, p. 18 - 25 (2019)

Pb-Zr mixed oxides with 15.2 wt% PbO loading were prepared by four different preparation processes, and their catalytic performances for the disproportionation of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC) were evaluated. Physicochemical characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF), BET surface area measurement, H2-temperature programmed reduction (H2-TPR), ammonia temperature programmed desorption (NH3-TPD) and infrared spectroscopy of pyridine adsorption (Py-IR), as well as catalytic tests of MPC disproportionation reaction showed that catalyst preparation process exerted significant influence on the composition, structural property, catalytic performance of obtained catalysts, and the catalyst prepared by co-precipitation method (PbZr-CP) demonstrated better dispersion of active phase, larger specific surface area and more Lewis acid sites on the surface due to the strong interaction of Pb and Zr, and thus exhibited higher catalytic activity than those prepared by other processes.

Synthesis of diphenyl carbonate from carbon dioxide, phenol, and carbon tetrachloride catalysed by ZnCl2 using trifluoromethanesulfonic acid as functional co-catalyst

Fan, Guozhi,Wang, Min,Duan, Zhenxiao,Wan, Minghai,Fang, Tao

, p. 1667 - 1673 (2012)

Diphenyl carbonate (DPC) was synthesised from carbon dioxide, phenol, and carbon tetrachloride catalysed by the Lewis acid ZnCl2 with the addition of co-catalyst. It was found that common bases are not effective co-catalysts for the production of DPC, and only slight enhancement in the catalytic activity of ZnCl2 was observed in the presence of inorganic additives such as inorganic carbonates and quaternary ammonium salts. Although poor conversion of phenol and yield of DPC were obtained using ZnCl2 or trifluoromethanesulfonic acid (CF3SO3H) as the sole catalyst, the catalytic activity of ZnCl2 was significantly improved by the addition of a catalytic amount of CF3SO3H. CF 3SO3H has been proven to be an effective co-catalyst. The conversion of phenol and the yield of DPC were dependent on the amount of ZnCl2 and CF3SO3H, the reaction temperature, and the pressure of CO2. A possible reaction mechanism for the synthesis of DPC catalysed by the co-catalytic system including ZnCl2 and CF3SO3H was also proposed.

Cyanoesterification of norbornenes catalyzed by palladium: facile synthetic methodology to introduce cyano and ester functionalities via direct carbon-carbon bond cleavage of cyanoformates

Nishihara, Yasushi,Inoue, Yoshiaki,Izawa, Seisuke,Miyasaka, Mitsuru,Tanemura, Kenki,Nakajima, Kiyohiko,Takagi, Kentaro

, p. 9872 - 9882 (2006)

Addition of cyanoformates (NC-COOR) to norbornene at 110 °C in the presence of Pd(PPh3)4 (10 mol %) as a catalyst affords with high selectivity the corresponding doubly functionalized polar norbornane derivatives bearing both cyano and ester groups. By using benzonorbornadiene and norbornadienes as the substrates, the reaction can be extended to synthesis of various functionalized norbornene derivatives in moderate to excellent yields. In most cases alkyl groups such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, and benzyl in the ester functionalities are applicable to the reactions. Oxidative addition of cyanoformates to Pd(0), insertion of norbornenes, and reductive elimination of the corresponding adducts constitute the proposed catalysis pathway.

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Oki,M.,Nakanishi,H.

, p. 3419 - 3423 (1971)

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A new efficient Pd-catalyzed synthesis of diphenyl carbonate with heteropolyacid as a cocatalyst

Yin, Guochuan,Jia, Chengguo,Kitamura, Tsugio,Yamaji, Teizo,Fujiwara, Yuzo

, p. 11 - 16 (2001)

A new catalytic system, Pd-Mn-HPA (heteropolyacid), has been found to be very efficient in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) with CO and oxygen at low pressure in the absence of solvent. Synergistic effect between W-Mo-heteropolyacid and Mn(OAc)2 was observed for regenerating the Pd(II) species from Pd(0). The ratio of W-Mo in heteropolyacid, efficiency of the heteropolyacid salts and the roles of tetrabutylammonium bromide and molecular sieves have been investigated in detail. Using suitable components of the catalyst system, 53% yield of DPC with a Pd turnover number of 827 can be attained.

Pd(NHC) electrocatalysis for phosgene-free synthesis of diphenyl carbonate

Kanega, Ryoichi,Hayashi, Tomohiko,Yamanaka, Ichiro

, p. 389 - 392 (2013)

Electrocarbonylation of phenol with CO to diphenyl carbonate was studied using a homogeneous Pd electrocatalyst. Various ligands were screened, and N-heterocyclic carbene (NHC) groups, such as 1,3-dimesitylimidazol-2-ylidene, were found to be effective for the electrocarbonylation. An in situ-generated NHC derived from a 1,3-dialkylimidazolium chloride was also effective for the electrocarbonylation, and 1,3-di(tert-butyl)imidazoline chloride was the most effective NHC precursor, with a stronger electron-donating ability to PdCl 2(MeCN)2 electrocatalyst.

Effect of zirconia polymorph on the synthesis of diphenyl carbonate over supported lead catalysts

Wang, Songlin,Niu, Hongying,Guo, Mengjun,Wang, Jianji,Chen, Tong,Wang, Gongying

, p. 117 - 124 (2019)

Zirconia supported Pb-based catalysts with purely tetragonal/monoclinic crystals were prepared and analyzed well by XRD, TEM-EDS, XPS, H2-TPR, BET, Py-IR and NH3-TPD techniques. The results indicate that zirconia polymorph has great effect on their structure and catalytic property for the synthesis of diphenyl carbonate (DPC) through methyl phenyl carbonate (MPC) disproportionation due to the differences of surface chemical properties, and tetragonal zirconia supported lead catalyst (TZ-Pb) shows bigger dispersion degree of PbO, higher surface area and Lewis acid amounts and thereby exhibits higher catalytic activity and selectivity compared to monoclinic zirconia supported catalyst (MZ-Pb). Furthermore, TZ-Pb shows better reusability due to strong metal-support interaction and may be readily recycled for at least four times without remarkable reactivity loss. This work provides a prospective reference for the facile and efficient synthesis of zirconia polymorph materials in various catalysis applications.

Light-induced synthesis of unsymmetrical organic carbonates from alcohols, methanol and CO2under ambient conditions

Saini, Sandhya,Gour, Nand Kishor,Khan, Shafiur Rehman,Deka, Ramesh Chandra,Jain, Suman L.

supporting information, p. 12800 - 12803 (2021/12/13)

The present work describes the first visible light-assisted, metal-free and organic base 1,1,3,3-tetramethyl guanidine (TMG) mediated synthesis of unsymmetrical methyl aryl/alkyl carbonates from the reaction of alcohols, methanol, and CO2 in high to excel

Rhodium-Catalyzed Carbonylative Synthesis of Aryl Salicylates from Unactivated Phenols

Ai, Han-Jun,Zhang, Youcan,Zhao, Fengqian,Wu, Xiao-Feng

supporting information, p. 6050 - 6054 (2020/10/02)

A rhodium-catalyzed carbonylative transformation of unactivated phenols to aryl salicylates is described. This protocol is characterized by utilizing 1,3-rhodium migration as the key step to provide direct access to synthesize ohydroxyaryl esters. Various desired aryl o-hydroxybenzoates were produced in moderate to excellent yields with bis(dicyclohexylphosphino)ethane (DCPE) as the ligand. Interestingly, diphenyl carbonate was formed as the main product when 1,3-bis(diphenylphosphino)propane (DPPP) was used as the ligand. A plausible reaction mechanism is proposed.