Synthesis of novel ionic liquid ([C4CNmim]+PF6 −) and application to preparation of polyketone

Abstract

N-valeronitrile-N′-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6−), as a novel ionic liquid with polar nitrile functional group, was prepared. The structure of the ionic liquid was characterized by using IR and 1H NMR. As a medium, the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St). Some synthetic conditions were determined, including the usage of ionic liquid, palladium composite catalyst and methanol, CO pressure, reaction time and reaction temperature. The influence of these factors on catalytic activity was analyzed. The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition: composite catalyst 0.015 mmol, ionic liquid 3 mL, methanol 0.75 mL, CO pressure 2 MPa, reaction time 2 h and reaction temperature 70 °C. This CO/St copolymerization within [C4CNmim]+PF6− system could facilitate ionic liquids with efficient and economical applications to polymeric materials.