Synthesis of p-Acetylaminophenol with Pipeline Reactor

OBJECTIVE To prepare p-aminophenol sodium based on p-nitrophenol sodium by amination in pipeline reactor. METHODS The solution mixed with 40% p-nitrophenol sodium solution-ammonia-1% ammonium chloridesolution solution(9.25∶1∶1.85) passed through the pipeline reactor(6 mm×3 mm×50 m) at the speed of 0.15 mL·s^-1　for 40 min with the temperature of 220 ℃, pressure of 6.0 MPa. Then p-nitrophenol sodium was prepared by the solution via desolventize, recrystallization, acidification and acetylation. RESULTS The melting point of p-aminophenol sodium achieved was 167-169 ℃, and the total yield was 72.7%. CONCLUSION The new process avoids the reduction step, reduces environmental pollution, and is more safety, controllable and the results are better than the normal process.