Search results for "Dimethyl carbonate"
showing 10 items of 24 documents
Reactivity of di-tert-butyldimethoxystannane with carbon dioxide and methanol: X-ray structure of the resulting complex
2006
Abstract The synthesis of dimethyl carbonate from carbon dioxide and methanol was studied with ditert-butyldimethoxystannane under pressure at temperatures ⩽423 K. The formation of dimethyl carbonate is accompanied by transformation of the stannane into a trinuclear complex, the structure of which has been determined by single-crystal X-ray diffraction technique. The relevance of this specie in the catalytic cycle is demonstrated by conducting recycling runs. A preliminary kinetic study underlines the steric influence of the tert-butyl ancillary ligands in the stabilisation of intermediates, by comparison with the n-butyl homologue.
Synthesis of dimethyl carbonate in supercritical carbon dioxide
2006
The reactivity of carbon dioxide with methanol to form dimethyl carbonate was studied in the presence of the n-butylmethoxytin compounds n-Bu3SnOCH3, n-Bu2Sn(OCH3)2 , and [n-Bu2(CH3O)Sn]2 O. The reaction occurred under solventless conditions at 423 K and was produced by an increase in CO2 pressure. This beneficial effect is primarily attributed to phase behavior. The mass transfer under liquid-vapor biphasic conditions was not limiting when the system reached the supercritical state for a CO2 pressure higher than 16 MPa. Under these conditions, CO2 acted as a reactant and a solvent.
Organo-catalyzed synthesis of aliphatic polycarbonates in solvent-free conditions
2012
A new efficient and expeditious route to the synthesis of aliphatic polycarbonates, in solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as a catalyst precursor, is described. The protocol consists of a two-step polymerization process involving the transesterification of dimethyl carbonate (DMC) with linear alkane diols and leading to high molecular weight homopolymers. The reaction went to completion quantitatively with the liberation of methanol as the only by-product. The in situ formation of N-heterocyclic carbene species resulting from BMIM-2-CO2 decarboxylation is suggested to be a key feature of the condensation process. The protocol was then …
Photocatalysis in dimethyl carbonate green solvent: degradation and partial oxidation of phenanthrene on supported TiO2
2014
Dimethyl carbonate (DMC) is here proposed – for the first time – as a green organic solvent for photocatalytic synthesis. In this work, the photocatalytic partial oxidation of phenanthrene in dimethyl carbonate (DMC) by using anatase TiO2 as the photocatalyst is described as paradigmatic example of a green synthetic process starting from polycyclic aromatic hydrocarbons (PAHs). For comparison, the same reaction carried out also in ethanol, 1-propanol or 2-propanol is reported. The use of DMC as the solvent allowed us to achieve 19% and 23% selectivity towards 9-fluorenone and 6H-benzo[c]chromen- 6-one, respectively. The proposed approach may represent both a new green synthetic process and …
1,3-Dimethylimidazolium-2-carboxylate: the unexpected synthesis of an ionic liquid precursor and carbene-CO2 adductElectronic supplementary informati…
2002
1,3-Dimethylimidazolium-2-carboxylate is formed in good yield, rather than the anticipated organic salt, 1,3-dimethylimidazolium methyl carbonate, as the reaction product resulting from both N-alkylation and C-carboxylation of 1-methylimidazole with dimethyl carbonate; the crystal structure of the zwitterion exhibits π-stacked rings and two-dimensional sheets constructed by hydrogen-bonds from imidazolium-ring hydrogens to the carboxylate group.
CO2 as a C1-Building Block for Dialkyl Carbonate Synthesis
2002
Carbon dioxide, one of the major man-made greenhouse gas, is a renewable resource of carbon which can be viewed as a C1 synthon to build valuable chemicals. The development of new applications is of major interest considering CO2 conversion and environmentally friendly reactions. As chemical catalysis offers interesting options, we are studying the molecular design of catalysts for the formation of dialkyl carbonates from alcohols and CO2. This paper reports results on the mechanistic approach for dialkyl carbonate formation with alkoxybutyl tin(IV) compounds. The insertion of CO2 into Sn-OR bonds (R = Me, 1Pr) occurs at atmospheric pressure and room temperature leading to alkylcarbonato ti…
Liquid–liquid equlibria of the system dimethyl carbonate+methanol+water at different temperatures
2006
Abstract In this work, experimental liquid–liquid equilibria (LLE) data of the dimethyl carbonate + methanol + water system are presented. The LLE of this system has been measured from 283 to 333 K. On the other hand, LLE and LVE of the binary system dimethyl carbonate + water have been measured. The equilibrium data presented are correlated using NRTL and UNIQUAC equations. The reliability of these models is tested by comparison with experimental results. Finally, the VLE for the system DMC + water at 101.3 kPa was predicted using the UNIQUAC model, with the adjusted parameters obtained from the LLE data. This prediction was successful when is compared with the experimental VLE data.
Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals
2015
Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a…
Linear Organic Carbonates
2003
The most common and successful method for producing organic carbonates, including polycarbonates, has been based for long time on the reaction between an alcohol or phenol and phosgene. The existing strict environmental regulations and the expanding market for organic carbonates do not assure that this technology can continue to have a leading role in this area, due to the inherent riskfulness of the processes. The market expansion of dimethyl carbonate (DMC), diphenyl carbonate (DPC), and bisphenol A polycarbonate (BPA-PC) is a reality, finding its driving force from the industrialization of alternative routes by EniChem (Italy) and UBE (Japan). This favorable situation can be foreseen for…
CO2: from waste to resource for methanol-based processes
2009
This paper reports on research aiming at developing sustainable processes for the production of methanol (CH3OH) and dimethyl carbonate (DMC, (CH3)2CO3) using carbon dioxide (CO2) as a raw material. Using carbon dioxide as a raw material has several advantages; it is non-toxic, in abundant supply, and promises innovative routes to the production of commodity chemicals. Methanol and dimethyl carbonate are important products and feedstocks of the chemical industry. Methanol is produced commercially from synthesis gas, but it is also possible to use carbon dioxide as a feedstock. Conventional production of dimethyl carbonate involves the use of toxic phosgene or carbon monoxide, while the met…