A preparation process of paracetamol are as follows:
(1) Add acetic acid, p-aminophenol, and metallic zinc with a molar ratio of 1.296:0.275:0.0046 into the reactor, stir and raise the temperature to 80°C, and obtain a reaction solution;
(2) Pump the reaction solution into the dehydration membrane device through a circulating pump. The water generated by the reaction diffuses to the back pressure side of the membrane. The pressure on the back pressure side is -0.09MPa. The water is continuously pumped out by the vacuum pump, prompting the reaction to continue until the reaction is completed. , reaction time is 4 hours;
(3) After the reaction is completed, cool the reaction solution to 25°C and crystallize for 1 hour; centrifuge and filter to obtain paracetamol crystals; vacuum dry at 50°C for 12 hours to obtain the finished paracetamol;
The HPLC content of the finished product was 99.6%, and the yield was 78%.