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SYNTHESIS OF CYCLIC ALKYLENE CARBONATES AT LOW TEMPERATURES AND PRESSURES

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Author(s): Vendelín Macho | Milan Králik | Milan Olšovský | Jana Horniaková | Dušan Mravec

Journal: Petroleum and Coal
ISSN 1337-7027

Volume: 50;
Issue: 1;
Start page: 30;
Date: 2008;
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Keywords: cyclic alkylene carbonates | alkene oxides | carbon dioxide | mild pressure | mild temperature

ABSTRACT
The addition of CO2 to propylene oxide (methyl oxirane) was used to examine the effect of catalytic systemsformed from Lewis bases, mainly N,N-dimethylformamide (DMF) and tributylamine (TBA), and preferentiallyhalides of transition metals of the iron triad (CoCl2, FeCl3 and NiCl2) and some Group 2 metal halides (CaCl2,MgBr2, ZnCl2, CaI2, and SnCl2) on the conversion of the addition and its selectivity to propylene carbonateformation (PC). The use of the hydrates of these halides and moisture in the reactants decrease PC selectivity.Almost quantitative conversion of propylene oxide can be achieved at a nearly optimum temperature of 120 + 2 oC anda total pressure of 3-4 MPa. Selectivities to PC ranged from 82 to 94% were obtained with DMF-CoCl2 >DMF-NiCl2 >DMF-CaI2 >DMF-CaBr2, followed by DMF-ZnCl2, DMF-CaCl2, DMF-FeCl3 and DMF-SnCl2. NaCl, NaBr, and CuCl2were inactive, as well the low active and nonselective were Co, Ni, Fe and Ca carboxylates, nitrates andcarbonates. The positive effect of CO2 pressure in the range of 1-3 MPa on the selectivity of the addition to cyclicalkylene carbonates at 120 + 2 oC was confirmed with 6 different epoxy compounds, as documented e.g. by thedata obtained with DMF (68,4 mmol)-CaCl2 (7.39 mmol) system: at 6-8 MPa and almost quantitative POconversion, PC selectivity was 62% while at 2-3 MPa PC equaled to 92%. With butene oxide, the selectivity tobutylene carbonate was 58%, at 7-9 MPa, while at 1-2 MPa PC amounted to 92%. A similar positive effect oflower pressure was confirmed also in the case of other epoxy compounds.
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