Synthesis
Method for synthesizing free base:
1) Prepare a solution of antipyrine with 50% sulfuric acid.
2)Flow the solution and sodium nitrite solution into the nitrosation reactor at the same time, control the flow rate of both, control the reaction temperature 45-50, react under stirring, and measure the reaction endpoint with iodine powder starch test paper to adjust the water flow rate.
3) The nitrosative antipyrine generated by nitrosation immediately flows into the reduction tank and reacts with the aqueous solution of reductant prepared in the tank.
4) Take a sample to measure the pH value, the pH value between 5.4-5.8 when the reduction is over, adjust the pH value to 5.8-6.0, raise the temperature to 100 , hydrolyze for 3h, lower the temperature to 80 , neutralize with liquid ammonia to pH 7-7.5, and leave it to stratify.
5) Separate the waste water to get 4-aminoantipyrine oil, which is pressed into a crystallization tank, stirred, cooled crystallized and filtered to get 4-aminoantipyrine.
