Introduction to pharmaceutical technology
General pharmaceutical technology mainly includes the following stages:
Raw material, pretreatment, chemical reaction, separation, purification, product, preparation, and medicine.
Taking the synthesis of nitrobenzene as a pharmaceutical intermediate as an example, the process is introduced as follows:
Mixed acid composition: HNO3 5%, H2SO4 68%, H2O 27%; the molar ratio of HNO3 in benzene to mixed acid is 1:1.1, and the reaction pressure is 0.46MPa; reaction temperature: 130 C; after the reaction, the nitrate enters the continuous separator and after separation the temperature of the acid nitrobenzene and the waste acid is about 120 C. The acidic nitrobenzene is sent to the refining section after cooling, alkali washing, water washing and the like.
Mixing nitric acid and circulating acid in proportion to form a uniform mixture containing about 5% nitric acid and about 68% sulfuric acid. The mixed acid is pumped to the tubular reactor, and with benzene (about 10% excess of benzene to avoid the formation of dinitrobenzene and ensure high yield of nitrobenzene) is subjected to continuous nitration to form nitrobenzene, the residence time is about 12 minutes; The water produced by the nitration reaction dilutes the sulfuric acid from 68% to about 65%, and the heat generated by the reaction raises the reaction temperature from about 95°C to about 130°C.
Plate Heat Exchanger in the Process
Acid nitrobenzene heat exchanger: The inlet temperature is 120°C, the benzene is heated to 90°from normal temperature, and mixed with acid to prepare nitrobenzene. (Nitrobenzene: light yellow transparent oily liquid, relative water density: 1.205)
Condenser: Cooling with circulating cooling water. The medium is a gas from a flash tank containing benzene, nitrobenzene, nitrogen oxides, etc., and condensed into a liquid.