API & Intermediate

Pyridine is a six membered heterocyclic compound containing one aza atom, that is, a compound formed by the substitution of one carbon in benzene molecule with nitrogen. It is similar to benzene in that it has the same electronic structure and still has aromaticity. Pyridine and its derivatives are more stable than benzene, and their reactivity is similar to nitrobenzene. Due to the electron absorption of nitrogen atoms in the ring, the electron density at positions 2, 4 and 6 is lower than that at positions 3 and 5. The typical aromatic electrophilic substitution reaction occurs at positions 3 and 5, but the reactivity is lower than that of benzene, so it is generally not easy to nitration, halogenation and sulfonation. In addition, these substitution reactions are carried out in acidic medium. Pyridine forms positively charged ions, which make electrophilic reagents inaccessible. The halogens of 2-or 4-halopyridines are active. Because of the low electron density at positions 2 and 6, nucleophilic substitution reactions can take place at these positions, such as reaction with sodium amino or potassium hydroxide, to give corresponding 2-aminopyridine or 2-hydroxypyridine. Pyridine can also be used as denaturant and dyeing aid in industry, as well as the starting material for synthesis of a series of products, including drugs, disinfectants, dyes, food seasonings, adhesives, explosives and so on. Pyridine is toxic, inhalation, ingestion or skin contact can lead to reduced male fertility, can also cause cancer.

Docetaxel is an anticancer and antitumor drug. It can be used to study antibiotics, cell biology, cell signal transduction, neuroscience, apoptosis and cell cycle. Docetaxel is also used to study hair loss caused by docetaxel chemotherapy, prevention and treatment of non-small cell lung cancer in patients with contraindicated standard chemotherapy.

Sofibibuvir is a prodrug, which can be metabolized to 2 '- deoxy-2' - deoxy-2 '- α- Fluorine- β- C-methyluridine-5 '- monophosphate, used in the treatment of hepatitis C. Sofibvir is a direct acting antiviral drug, which inhibits HCV RNA dependent RNA polymerase, NS5B Gene. NS5B Gene is essential for HCV replication.

Fipronil is the first benzopyrazole used for pest control. Since its discovery in 1987, it has been widely used in many fields such as agriculture and veterinary medicine, and has become an important insecticide variety. Non prednisolone, trade name regent, is a new type of benzopyrazole insecticide. Compared with traditional insecticides (organophosphorus, pyrethroid and carbamate), it has the advantages of broad spectrum and high efficiency. It has been widely used in many agricultural fields and is a common insecticide for pest control. Fipronil is mainly produced by blocking γ- Aminobutyric acid receptor controlled Cl - channel induces Cl - flow, which causes the nervous system to be extremely excited and leads to the death of insects, so as to achieve the control effect on a variety of economic pests.

Ammonium chloride (chemical formula: NH4Cl) is colorless cubic crystal or white crystal. It tastes salty, cool and slightly bitter. It is easily soluble in water and liquid ammonia and slightly soluble in alcohol, but insoluble in acetone and ether. The aqueous solution is weakly acidic and the acidity increases when heated. Due to the coordination of ammonium ions, the ammonium chloride solution is corrosive to metals, especially copper.