Synthesis of N-vinyl pyrrolidone by acetylene process in a microreactor

Vinylation reaction of 2-pyrrolidone with acetylene to synthesize N-vinyl pyrrolidone was successfully implemented in a microreactor. The application of microreactor not only avoided the safety issue caused by acetylene decomposition and explosion, but also intensified gas-liquid mass transfer and improves the selectivity of N-vinyl pyrrolidone to 100%. The catalyst and reaction performance of vinylation reaction were investigated in detail. First of all, potassium salt, the homogeneous catalyst for this reaction was prepared and potassium pyrrolidone was identified to be the catalytic active species through comparison among different precursors. In addition, the catalyst was confirmed to have pretty good stability. Then the effects of the reaction conditions were clarified such as gas-liquid ratio, reaction pressure and the catalyst content. Both pressurization and higher KOH content were beneficial to convert more reactants. Finally, to realize the efficient transformation of the reactants, the liquid phase was recycled to obtain the sufficient gas-liquid contact time. After four-round cycling liquid phase, the conversion of 2-pyrrolidone was up to 45.3%.