Methyl Phenyl Carbonate Research Articles

Development and optimization of a method for analysis of the products from the transesterification of dimethyl carbonate and phenol

A high-purity sample of methyl phenyl carbonate (MPC) was obtained by developing a novel reaction route followed by a series of separation and purification procedures. Identification and quantification of the MPC sample (98.32%) was performed by a gas chromatography-mass spectrometry and Karl Fisher titration. The laboratory-prepared MPC was then used as a standard to optimize quantitative analysis of the products synthesized by transesterification of dimethyl carbonate and phenol. The advantage of the improved method was that MPC can be quantified directly rather than being calculated by subtracting the yield of diphenyl carbonate (DPC) and by-product anisole from the conversion of dimethyl carbonate (DMC). The resulting method was validated for linearity, precision, accuracy, detection limit, and quantification limit. With the improved method, simultaneous accurate quantification of DMC, MPC, DPC, phenol, and anisole in the transesterification products can be achieved. This enables evaluation of the activity and selectivity of different catalysts and control of the reaction processes.

Novel catalytic systems containing n-BuSn(O)OH for the transesterification of dimethyl carbonate and phenol

Novel catalytic systems containing n-butylstannonic acid ( n-BuSn(O)OH) were used to synthesize methyl phenyl carbonate (MPC) and diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol in atmospheric conditions. The catalytic system consisting of n-BuSn(O)OH and cuprous iodide (CuI) had the highest activity for the transesterification. When the reaction was carried out between 150 and 180 °C, with a molar ratio of n-BuSn(O)OH to CuI of 1:1, a catalyst amount 0.005 (molar ratio to DMC), a reaction time 10 h, a molar ratio of DMC to phenol of 2:1, a dropping time of DMC 6 h, the conversion of phenol was 67.2%, and the selectivity of MPC and DPC was 40.2 and 59.6%, respectively. Upon comparison of the activities of Cu 2O, CuX (X = Cl, Br, I) and the catalytic system being composed of n-BuSn(O)OH and Cu 2O/CuX, it was found that Cu 2O and CuX were excellent promoters, and the stronger was the anion electronegativity in the promoter, the weaker was the promoting catalysis of the promoter.

Synthesis of diphenyl carbonate from dimethyl carbonate and phenol using O 2-promoted PbO/MgO catalysts

Various heterogeneously supported PbO catalysts were prepared for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate (DMC) with phenol. MgO was found to be the best support, and the modification by oxygen further enhanced the catalytic activities of PbO/MgO catalysts. Several parameters affecting the transesterification were investigated. The yields of methylphenyl carbonate (MPC) and DPC reached 10% and 26.6%, respectively, over 10 wt% O 2-promoted PbO/MgO catalyst which was prepared by impregnation method. X-ray diffraction (XRD), differential thermal analysis (DTA) and Brunauer–Emmet–Teller (BET) technique were employed for the characterization of prepared catalysts. It was discovered that the structure and the oxidation states of lead species in PbO/MgO catalysts changed after the promotion by oxygen.

Highly selective methoxycarbonylation of aliphatic diamines with methyl phenyl carbonate to the corresponding methyl N-alkyl dicarbamates

The reactivity parameters of aliphatic diamines such as 1,6-hexanediamine, 1,3-bis(aminomethyl)benzene and 1,3-bis(aminomethyl)cyclohexane, with methyl phenyl carbonate, were investigated under mild conditions. Methoxycarbonylation of aliphatic diamines with methyl phenyl carbonate proceeds selectively in the absence of a catalyst, quantitatively converting aliphatic diamines to the corresponding methyl N-alkyl dicarbamates at 323–363 K.

Carbomethoxylating reactivity of methyl phenyl carbonate toward aromatic amines in the presence of group 3 metal (Sc, La) triflate catalysts

Methyl phenyl carbonate (MPC) has been investigated as a carbomethoxylating agent of aromatic amines in the presence of group 3 metal (Sc or La) triflate catalysts. Under mild conditions (363 K), both Sc(OTf) 3 and La(OTf) 3 (OTf = O 3SCF 3) can promote the carbamation of aniline and a few industrially relevant aromatic diamines, such as 4,4′-methylenedianiline (MDA) and 2,4-diaminotoluene (TDA), with MPC. Carbamate yield and selectivity are markedly affected by the experimental conditions (temperature, reaction medium, nature of the metal center). Sc(OTf) 3 is a more effective and selective carbamation catalyst than La(OTf) 3. Ad hoc experiments have shown that, in the presence of the M(OTf) 3 (M = Sc, La) catalysts, MPC is not only more reactive but also a more selective carbomethoxylating agent than dimethyl carbonate (DMC).

The Transesterification of Dimethyl Carbonate with Phenol over Mg−Al-hydrotalcite Catalyst

The production of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol was performed using a variety of solid catalysts. Mg−Al-hydrotalcite was found to have a high activity for this transesterification. A 14.7% yield of DPC and an 11.6% yield of methylphenyl carbonate (MPC) based on DMC were obtained in the presence of Mg−Al-hydrotalcite catalyst. The optimum experimental temperature for this transesterification reaction was between 160 and 180 °C, which was in agreement with the thermodynamic analysis. When the transesterification of DMC with phenol was performed at the molar ratio of phenol to DMC of 2:1, reaction time 10 h, 1.0% of 2:1 Mg−Al-hydrotalcite based on the total weight of reactants, and 160−180 °C, the total yield and selectivity for DPC and MPC were 26.3 and 82.4%, respectively. The yield of anisole was 5.6%.

Effect of calcination conditions on MoO3/SiO2 catalysts for synthesis of methylphenyl carbonate

The effect of calcination conditions on MoO3/SiO2 catalysts for the synthesis of methylphenyl carbonate was investigated in terms of catalytic activities and surface properties. The calcination temperature was varied in the range of 300 to 800oC. These calcination conditions have shown a close relationship with the catalyst activities. The optimal calcination temperature of MoO3/SiO2was found to be around 550-600oC. The catalysts were characterized by XRD, SEM, FT-IR and XPS analysis.

Loss of CO2 from the ortho isomer of deprotonated methyl phenyl carbonate involves a methyl migration

The collision induced decompositions of the ortho-, meta, and para- (M − H)− anions of methyl phenyl carbonate were studied to see whether there is loss of CO2 occurring by the benzyne cine-substitution {(C6H4)− − OCO2Me → [(C6H4)MeOCO2−] → (C6H4)− − OMe + CO2}. Loss of CO2 is observed from the ortho isomer, but the process does not involve a benzyne cine substitution. It is a methyl migration through a six-centre transition state to give a cresol (M − H)− ion, probably ortho-MeC6H4 − O−. Theoretical calculations [at the B3LYP/6-311++G(d,p)//HF/3-21+G(d) level of theory] indicate the methyl migration is a stepwise process, with the barrier for the first (and rate determining) step being 191 kJ mol−1. The overall process is calculated to be exothermic by 276 kJ mol−1.

Gas Phase Transesterification of Dimethylcarbonate and Phenol over Supported Titanium Dioxide

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.

A new process for the synthesis of diphenyl carbonate from dimethyl carbonate and phenol over heterogeneous catalysts

The two-step synthesis of diphenyl carbonate (DPC) from dimethyl carbonate (DMC) and phenol has been compared in liquid phase and gas phase, both over heterogeneous catalysts. In the first step, equilibrium yields of methyl phenyl carbonate (MPC) in the transesterification of DMC and phenol were very low at low temperatures in the liquid phase although reaction rates were fast. This endothermic reaction was more favorable at high temperatures in the gas-phase reaction. Titanium oxide catalysts supported on SiO2 or activated carbon were found to be effective in a continuous gas flow reactor. In case of the second step, the disproportionation of MPC, selective formation of DPC was not feasible in the gas-phase reaction due to extensive side reactions. However, there was no by-product in the liquid-phase reaction over the TiO2/SiO2 catalyst. Therefore, our proposed two-step synthesis process consists of the gas-phase transesterification of DMC and phenol followed by the liquid-phase disproportionation of MPC to DPC, both over the TiO2/SiO2 catalyst.

Selective carbomethoxylation of aromatic diamines

The reactivity of industrially relevant amines, 4,4′-methylenedianiline (MDA) and 2,4-diaminotoluene (TDA), towards methylphenylcarbonate (MPC), in the presence of Ph2P(O)OH, has been investigated. Both MDA and TDA are catalytically and selectively converted into mono- and di-methylcarbamate esters. Under the relatively mild working conditions used, the formation of ureas and/or N-methyl derivatives is totally repressed. The full spectroscopic characterization of the compounds formed upon interaction of amines with Ph2P(O)OH is also reported. The methodology here described also holds for other mono- and di-amines, both aliphatic and aromatic.

Two-step synthesis of diphenyl carbonate from dimethyl carbonate and phenol using [formula omitted] catalysts

The transesterification of dimethyl carbonate with phenol to produce methyl phenyl carbonate was carried out in an autoclave using a variety of solid catalysts. MoO 3 SiO 2 was found to have a very high activity for this transesterification. Thus, a 17.1% yield of methyl phenyl carbonate based on phenol was obtained at 433 K in the presence of MoO 3 SiO 2 . MoO 3 SiO 2 was also an active catalyst for the disproportionation of methyl phenyl carbonate into diphenyl carbonate and dimethyl carbonate. A 48% yield of diphenyl carbonate was attained over MoO 3 SiO 2 at 443 K. These yield values are probably very close to those at the thermodynamic equilibrium.

Dimethyl carbonate for environmentally benign reactions

Dimethyl carbonate (DMC) is a unique molecule having a versatile reactivity. The transesterification of DMC with phenol gives methyl phenyl carbonate, which is converted into diphenyl carbonate (DPC) by disproportionation. MoO 3/SiO 2 is an active catalyst for both reactions. DPC is an essential monomer in the non-phosgene route for polycarbonates. The methoxycarbonylation of aniline gives methyl N-phenyl carbamate in the presence of a lead compound. This reaction offers a non-phosgene route to isocyanates. As a methylating agent, DMC can be a substitute for methyl halides and dimethyl sulfate, toxic and corrosive chemicals. Phenylacenitrile, aniline and phenol are selectively methylated with DMC over zeolites in the vapor-phase. The reaction of DMC with silica offers a simple and clean method for synthesizing Si(OCH 3) 4.

Dimethyl carbonate for environmentally benign reactions

Abstract

Broensted plots in the reactions of 2,4-dinitrophenyl acetate and methyl phenyl carbonate with substituted pyridines

Broensted plots in the reactions of 2,4-dinitrophenyl acetate and methyl phenyl carbonate with substituted pyridines