Synthesis of n-vinyl carbazole from acetylene by a continuous high-pressure liquid-phase process with Inherent safety

Abstract

In this study, a continuous high-pressure liquid-phase acetylene microreaction process is rationally designed and successfully realized by employing the strategy of decoupling the acetylene dissolution and successive reaction. As the acetylene reaction is operated in a pure liquid phase with high acetylene concentration, the safety and efficiency of the acetylene conversion process are greatly improved. As a result, N-vinylcarbazole (NVC) is continuously synthesized from dissolved acetylene at 165 °C and 4.5 MPa. Compared to the conventional batch process, the reaction time is reduced to 5–20 min from 5 to 6 h, the amount of catalyst is reduced by 14.8 times, and the specific activity (g carbazole /g KOH /min) is increased by 220 times. To further increase the yield of NVC, 4-tert-butylcatechol (TBC) is added to the feedstock as a polymerization inhibitor, which improves the yield of NVC to 88 %. Several other vinyl compounds, in addition to NVC, are also continuously synthesized from acetylene using this method, which suggests that the process decoupling reaction strategy is widely applicable to acetylene-involved reactions.