Yutaka Ikushima

Synthesis of dimethyl carbonate and glycols from carbon dioxide, epoxides, and methanol using heterogeneous basic metal oxide catalysts with high activity and selectivity

Abstract This paper gives a comprehensive report on a two-step synthesis of dimethyl carbonate (DMC) from epoxides, carbon dioxide and methanol using various basic metal oxide catalysts. The first step is the reaction of ethylene oxide or propylene oxide with CO 2 to form the corresponding cyclic carbonates, and the second step is the transesterification reaction of the cyclic carbonates with methanol to DMC and glycols. Among the catalysts examined, MgO is the most active and selective for both these reactions. Other alcohols can be used for the second step, but the activity decreases as the carbon number of the alcohol increases. Although a one-pot synthesis of DMC, i.e. the sequential reaction of the epoxide, CO 2 and methanol, is also possible with MgO, the selectivity is low because of the alcoholysis of the epoxide. In contrast with the reactions of ethylene oxide and propylene oxide, when styrene oxide is used for the first reaction and for the one-pot synthesis, mandelic acid is produced. Basic properties of the metal oxide catalysts were measured by temperature programmed desorption of CO 2 . The relationship between the catalytic performance and the basic property is discussed.

The leaching and re-deposition of metal species from and onto conventional supported palladium catalysts in the Heck reaction of iodobenzene and methyl acrylate in N-methylpyrrolidone

When supported palladium catalysts are used for Heck vinylation of iodobenzene with methyl acrylate in N-methylpyrrolidone (NMP) in the presence of triethylamine and sodium carbonate bases, the reaction proceeds homogeneously with dissolved active palladium species that are formed through coordination of NMP and triethylamine with palladium. These active species easily react with iodobenzene (oxidative addition), beginning the catalytic cycle of Heck coupling. The last step of catalyst regeneration takes place with the action of sodium carbonate. The active palladium species are not stable and deposit the metal to support when they cannot find iodobenzene to react in the reaction mixture after this substrate is completely consumed. The re-deposition of palladium occurs on the surfaces of bare support and/or palladium particles remaining on it, depending on the nature of support surface and the number and size of residual metal particles. The growth of palladium particles has been observed after the reuse of catalyst in some case. However, the supported catalysts are recyclable without loss of activity.

Synthesis of dimethyl carbonate and glycols from carbon dioxide, epoxides and methanol using heterogeneous Mg containing smectite catalysts: effect of reaction variables on activity and selectivity performance

This paper reports the effect of various reaction variables on the activity and selectivity performance on a two-step synthesis of dimethyl carbonate (DMC) and glycol from propylene oxide, carbon dioxide and methanol using a heterogeneous Mg containing smectite catalyst. The first step, the reaction of propylene oxide with CO2 to form propylene carbonate, and the second step, the transesterification reaction of the cyclic carbonate such as ethylene carbonate with methanol to DMC and ethylene glycol, have been studied. The catalyst was found to be effective for one-pot synthesis of DMC, i.e. the sequential reaction of the epoxide, CO2 and methanol.

Transesterification of urea and ethylene glycol to ethylene carbonate as an important step for urea based dimethyl carbonate synthesis

Two-step synthesis of dimethyl carbonate (DMC) from urea has been investigated with various solid catalysts. The first step involves reaction of urea with ethylene glycol (EG) to form ethylene carbonate (EC) and the second step transesterification of EC formed with methanol to give DMC and EG. It has been found that ZnO is highly active and selective for the two steps, of which the former should be conducted under reduced pressure. At around ambient pressure, 2-oxazolidone and ethyleneurea are formed in the first step. Similar to EG, other glycols such as 1,2- and 1,3-propanediols can also be transformed to corresponding cyclic carbonates.

Synthesis of cyclic ureas and urethanes from alkylene diamines and amino alcohols with pressurized carbon dioxide in the absence of catalysts

Clean synthesis to imidazolidone and oxazolidone compounds using direct reaction of carbon dioxide with diamine or amino alcohols can be achieved at 6 MPa CO2 and 150 °C without use of any catalyst.

Chemical fixation of carbon dioxide to propylene carbonate using smectite catalysts with high activity and selectivity

The reaction of propylene oxide and carbon dioxide to propylene carbonate was carried out using Mg-, Ni- and Mg-Ni-containing smectite catalysts which contain different amounts of alkali atoms such as sodium, potassium and lithium. These catalysts are highly active and selective for this reaction. The catalytic activity strongly depends on the elemental composition of the catalyst used. Particularly the amount of alkali atoms incorporated in the catalyst is the most important factor governing the catalytic performance. The most active catalyst among those prepared in the present study shows a turnover number of 105 mmol/g for the propylene carbonate formation, which is the highest turnover number compared with those reported so far (10 mmol/g) for the title reaction.

A rapid and effective synthesis of propylene carbonate using a supercritical CO2–ionic liquid system

The synthesis of propylene carbonate from propylene oxide and carbon dioxide under supercritical conditions in the presence of 1-octyl-3-methylimidazolium tetrafluoroborate was achieved in nearly 100% yield and 100% selectivity within 5 minutes, whose TOF value is 77 times larger than those so far reported.

Concurrent Synthesis of Dimethyl Carbonate and Ethylene Glycol via Transesterification of Ethylene Carbonate and Methanol Using Smectite Catalysts Containing Mg and/or Ni

Smectites containing magnesium and/or nickel in the lattice were found to be excellent heterogeneous catalysts for the concurrent synthesis of dimethyl carbonate and ethylene glycol by transesterification of ethylene carbonate with methanol. The catalytic activity strongly depends on the elemental composition of the catalysts and is correlated with the number of moderately basic sites present on the catalyst.

Regioselectivity and selective enhancement of carbon dioxide fixation of 2-substituted aziridines to 2-oxazolidinones under supercritical conditions

Under supercritical CO2 conditions, regioselectivity in the carbon dioxide fixation of 2-substituted aziridines to 2-oxazolidinones was observed with good yields around 75%. Furthermore, when propylene imine was used in the place of aziridine, the yield was significantly and selectively increased around the critical pressure, and the maximum yield was obtained at 11.8 MPa. The turnover frequency (TOF) at this pressure is 2.1 times greater than that of a hitherto reported TOF which was obtained in ethanol at 6.9 MPa.

Innovation in a Chemical Reaction Process Using a Supercritical Water Microreaction System : Environmentally Friendly Production of ε-Caprolactam

Our microreaction system using supercritical water solutions achieves nearly 100% yield and 100% selectivity for epsilon-caprolactam production at reaction times shorter than 1 s.