2 Design Principles
Advanced technology, reasonable economical input, waste water, waste gas and waste solid disposal are always the typical topics.
(1)Design project including simple process, contracted equipment, convenient control and good quality product was first considered.
(2)Low cost (cost in investment and maintenance) and high efficient process must be considered.
(3)Considering raw material resources and plant scale, the source should be sufficient, convenient and low cost.
(4)Understanding the physical and chemical properties of raw materials and products.
3 Technical Introductions
(1)Product Introduction
Acetaminophen, shortly named as APAP, is an orderless white crystalline powder with slight bitter taste. Its density is 1.293g/cm3 and m.p. is 169-170.5℃. Acetaminophen can be dissolved in organic solvents such as methanol, acetone, ethyl acetate, hot water etc., but it can hardly be dissolved in cold water and ethyl ether.
APAP is an antipyretic analgesic with antiphlogistic and antiviral function. Compared with Aspirin, APAP is better in many aspects such as antipyretic effect, side effect etc. It also can be used for synthesizing pharmaceutical.
(2)Main Reaction Equation:
(3)Synthetic method
Now in China the one-step synthesis with iron powder as a reductant has been adopted, because the cost is high and the iron pollution is hard to treat. In recent years, developed countries use the hydrogenation process, especially catalytic hydrogenation
and one-step synthesis, to replace the iron powder reduction. The one-step synthesis does not need to separate PAP intermediate, shortens the craft route and reduces the oxidation of PAP. Also, it needs fewer procedures, saves the energy and reduces the pollution.
In this chapter we focus on that PAP is acetated to APAP by two-steps synthesis.
(4)Procedure
This design mainly involves three main steps: acylation, refining and dry. The following is the details.
Compounding: Matching of material based on fixed ratio under given condition.
Acylation: Acylating raw material matched under given condition.
Crystallization: Cooling solution acetated with cool water in cooling pan, then filtrating by centrifuge.
Decolorization: Decolorizing for gloss crystal with active carbon, then filtrating.
Crystallization.
Dry and packing.