Diversification of product-derived ionic liquids and application in DMC synthesis without introducing any impurities

Various strongly basic ionic liquids with distinctive structures, including single and double ended quaternary ammonium and phosphorus salts, were first synthesized based on hydroxyethoxy anion (HOCH2CH2O-) from the product ethylene glycol. Nature was characterized by NMR, FTIR, TG and acid-base titration. Its alkali strength was equivalent to that of sodium methoxide, demonstrating superior alkalinity. Influences of cation structures and C-1-C-4 alcohols structures on transesterification efficiency were investigated. Under mild conditions (68 degrees C for 5 min), DMC yield was 42.8% with a TOF value of 2853.6 h(-1) when [TBAB]OCH2CH2OH as catalyst with only 0.18% EC molar content, indicating good catalytic performance. Comparison was made for reaction results between the synthesized catalysts and reported catalysts in literatures. The reaction mechanism was further deduced. Activation energies of positive and reverse reactions were determined as Ea(+)=32.0kJ center dot mol(-1) and Ea(-)=15.3 kJ center dot mol(-1) through kinetics calculation. Relying on its decomposability and recyclability of decomposition products, a new catalyst circulation process without introducing any impurities was proposed and verified.

Automated summary

Various strongly basic ionic liquids were synthesized using hydroxyethoxy anion from ethylene glycol. The alkalinity of these liquids was equivalent to sodium methoxide and they exhibited good catalytic performance in transesterification reactions. By comparing with reported catalysts, the reaction mechanism was deduced and the activation energies were determined. A new catalyst circulation process without introducing impurities was proposed and verified.