Highly efficient and stable PbO–ZrO 2 catalyst for the disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate

Mesoporous PbO nanoparticle-catalyzed synthesis of arylbenzodioxy xanthenedione scaffolds under solvent-free conditions in a ball mill

A protocol for the efficient synthesis of arylbenzodioxy xanthenedione scaffolds was developed via a one-pot multi-component reaction of aromatic aldehydes, 2-hydroxy-1,4-naphthoquinone, and 3,4-methylenedioxy phenol using mesoporous PbO nanoparticles (NPs) as a catalyst under ball milling conditions. The synthesis protocol offers outstanding advantages, including short reaction time (60 min), excellent yields of the products (92-97%), solvent-free conditions, use of mild and reusable PbO NPs as a catalyst, simple purification of the products by recrystallization, and finally, the use of a green process of dry ball milling.

Influence of coordinating groups of organotin compounds on the Fries rearrangement of diphenyl carbonate

In this paper, the Fries rearrangement of diphenyl carbonate (DPC) catalyzed by organotin compounds with different coordination groups was studied for the first time. The electronic effect and steric hindrance of the coordinating groups were discussed with respect to the reactivity of DPC rearrangement. The results showed that both the electronic effect and steric hindrance of the coordinating groups influenced the acidity of the active tin centers and then affected the catalytic performance of organotin as a Lewis acid for the rearrangement of DPC, and the influence of the electronic effect is greater than that of steric hindrance. The catalytic activity is in the order of BuSnO(OH) > Bu2SnO > Bu2Sn(OCOC11H23)2 > BuSnCl3 > Bu3SnOSnBu3 > Bu3SnCl, and Bu2SnO showed the best catalytic activity due to its strong electron absorption effect, small steric hindrance, and good stability. Under the optimum reaction conditions, the conversion of DPC was up to 93%, and the yields of phenyl salicylate (PS) and xanthone (XA) were 62% and 28%, respectively. In addition, a reaction mechanism of DPC rearrangement catalyzed by the organotin compounds was speculated. This research can provide vigorous theoretical data support to control the byproducts produced by DPC rearrangement in the process of DPC synthesis. It also provides a new route for the preparation of PS and XA.

Highly effective transformation of methyl phenyl carbonate to diphenyl carbonate with recyclable Pb nanocatalyst

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.

Qualitative and Quantitative Analysis of the Product and By-Products from Transesterification between Phenol and Dimethyl Carbonate

By-products (phenyl salicylate, phenyl 4-hydroxybenzoate, and xanthone) from transesterification between phenol and dimethyl carbonate (DMC) were qualitatively analyzed by gas chromatography-mass spectrometry, and a gas chromatographic method with directed injection for simultaneous quantitative analysis of the product (DPC) and by-products of the transesterification has been established. Based on the results of qualitative and quantitative analyses, the mechanism of the by-products generation was preliminarily deduced. The sample for quantitative analysis was directly diluted in acetone, and related compounds were separated on an HP-5 capillary column and detected by a hydrogen flame ionization detector (FID). The product and by-products were well separated, the correlation coefficients (r) within the concentration range of 1.0 μg/mL-100 μg/mL were ≥0.9997, the relative standard deviations were between 0.5% and 4.4%, spiked recoveries were between 91.5% and 105.6%, and detection limits were between 0.11 and 0.18 μg/mL. The established method is simple, rapid, accurate, sensitive, and highly specific. It is suitable for simultaneous qualitative and quantitative analyses of the product and by-products of transesterification between phenol and DMC.

Ti functionalized hierarchical-pore UiO-66(Zr/Ti) catalyst for the transesterification of phenyl acetate and dimethyl carbonate

Uniformly distributed tetra-coordinated Ti^IV active sites grafted on hierarchical-pore UiO-66(Zr/Ti) as an efficient catalyst for synthesizing diphenyl carbonate.