Heyuan Song

Progress in synthesis of ethylene glycol through C1 chemical industry routes

Ethylene glycol (EG) is an important industrial chemicals. It has attracted attention because it can be used to synthesize polyester resins and fibers. C1 chemical industry routes have been explored for EG synthesis from syngas and coal as starting materials. It is suggested that such routes are more promising methods for EG synthesis than the use of petroleum is. The pertinent literature on EG synthesis through C1 chemical industry routes are summarized. The methods include direct synthesis from syngas, carbonylation of formaldehyde, CO coupling reactions, hydroformylation of formaldehyde, and condensation of formaldehyde.

Novel Acidic Ionic Liquids as Efficient and Recyclable Catalysts for the Cyclotrimerization of Aldehydes

Abstract A mild, efficient, and ecofriendly procedure for cyclotrimerization of aldehydes was realized by using a series of novel Brønsted acidic ionic liquids (BAILs) consisting of double–SO3H groups in cations as catalysts. Good conversion of aldehydes and selectivity of trialkyl-1,3,5-trioxanes were achieved by using 1 mol% of BAILs. In addition, the catalyst system could be recycled and reused at least eight times without apparent loss of activity. GRAPHICAL ABSTRACT

Brönsted Acidic Ionic Liquids as Efficient and Recyclable Catalysts for the Carbonylation of Formaldehyde

Methyl glycolate (MG), as a precursor to ethylene glycol (EG), was synthesized by an efficient and eco-friendly procedure of one-pot, two-step, sequential reaction, including carbonylation and esterification from HCHO with Brönsted acidic ionic liquids (BAILs) as catalysts. MG was obtained in high yield under mild conditions. In addition, the catalyst could be recycled eight times after separating the unreacted materials and products from the reaction system by distillation under vacuum and no significant decrease in catalytic activity was observed.Graphical AbstractMethyl glycolate (MG) was successfully synthesized from the carbonylation of HCHO using Brönsted acidic ionic liquids (BAILs) as catalysts, followed by esterification with methanol. The conversion of HCHO and yield of MG could up to 99.2% and 98.0%, respectively. The catalyst and solvent could be separated and reused at least eight times without apparently loss of activity.

Brønsted-acidic ionic liquids as efficient catalysts for the synthesis of polyoxymethylene dialkyl ethers

Abstract Acetalation of formaldehyde (HCHO) with dialkyl formal or aliphatic alcohol to prepare polyoxymethylene dialkyl ethers (RO(CH2O)nR, n ≥ 1) catalyzed by Bronsted-acidic ionic liquids has been developed. The correlation between the structure and acidity activity of various ionic liquids was studied. Among the ionic liquids investigated, 1-(4-sulfonic acid)butyl-3-methylimidazolium hydrogen sulfate ([MIMBs]HSO4) exhibited the best catalytic performance in the reaction of diethoxymethane (DEM1) with trioxane. The influences of ionic liquid loading, molar ratio of DEM1 to HCHO, reaction temperature, pressure, time, and reactant source on the catalytic reaction were explored using [MIMBs]HSO4 as the catalyst. Under the optimal conditions of n([MIMBs]HSO4):n(DEM1):n(HCHO) = 1:80:80, 140 °C, and 4 h, the conversion of HCHO and selectivity for DEM2–8 were 92.6% and 95.1%, respectively. The [MIMBs]HSO4 catalyst could be easily separated and reused. A feasible mechanism for the catalytic performance of [MIMBs]HSO4 was proposed.

Functional Ionic Liquids as Efficient and Recyclable Catalysts for the Methylation of Formaldehyde with Aromatics

Methylation of formaldehyde with various aromatics under functional ionic liquids catalysis has been developed. Among the ionic liquids investigated, triphenyl-(4-sulfobutyl)-phosphonium triflate ([TTPBs][CF3SO3]) showed high activity and afforded excellent yields of diarylmethane derivatives. A mechanism for the catalytic performance of [TTPBs][CF3SO3] is proposed. Besides, the catalyst can simply be separated from the reaction mixture by centrifugation and be recycled ten times without noticeable loss of activity.Graphical AbstractDiarylmethane derivatives were successfully synthesized from the methylation of formaldehyde with aromatics using efficient and recyclable functional ionic liquids as catalysts, excellent yields and selectivities were obtained under solvent free conditions. The catalyst was reused at least ten consecutive recycles without noticeable loss in its catalytic activity. Meanwhile, the usability of catalyst was explored.

Efficient and reusable SBA-15-immobilized Brønsted acidic ionic liquid for the ketalization of cyclohexanone with glycol

Ketalization of cyclohexanone with glycol has been carried out using molecular sieve SBA-15 immobilized Bronsted acidic ionic liquid catalyst. The properties of the heterogeneous catalysts were characterized by elemental analysis, Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), thermogravimetry/differential scanning calorimetry (TG/DSC), and N2 adsorption–desorption (BET). The results suggested that Bronsted acidic ionic liquid [BSmim][HSO4] had been successfully immobilized on the surface of SBA-15 and the catalytic performance evaluation demonstrated that the catalyst BAIL@SBA-15 exhibited excellent catalytic activities in the ketalization of cyclohexanone with glycol. In addition, the effects of reaction temperature, catalyst loading, reaction time, and reactant molar ratio have also been investigated in detail, and a general reaction mechanism for the ketalization of cyclohexanone with glycol was given. The SBA-15 immobilized ionic liquid can be recovered easily and after reusing for 5 times in the ketalization reaction, the catalyst could still give satisfactory catalytic activity.

Synthesis and physicochemical characterization of polyoxymethylene dimethyl ethers

Abstract Polyoxymethylene dimethyl ethers (H3CO(CH2O)nCH3, PODEn or DMMn, n ≥ 2) with unique physical and chemical properties are a potential additive for diesel fuels, which can effectively enhance the combustion efficiency and reduce the emission of pollutants. In this work, a series of pure PODEn components (n = 2–5) were synthesized from methylal and trioxymethylene and obtained with high purity through collaborative separation; their structure and properties were characterized by NMR, FT-IR, Raman, DSC and DFT calculation and a detailed assignment of the expressions in the spectrogram to the various groups was performed. A detailed assignment of expressions in the spectrogram to the various groups was also performed. The density and viscosity of PODEn were measured at 298.15–323.15 K. The results indicate that the density and viscosity of PODEn decrease gradually with the increase of temperature. Meanwhile, with the increase in the number of –CH2O– units (n) from 2 to 5, the density, viscosity, flash point, pour point, and the heat of fusion and solidification of PODEn are all increased with the increase in the chain length. These results are valuable for the practical synthesis and application of PODEn.