Morpholine contains secondary amine groups and has all the typical reactive characteristics of secondary amine groups. It can react with inorganic acids to form salts, and react with organic acids to form salts or amides, which can be subjected to alkylation reaction, and can also be reacted with ethylene oxide, ketone or Willgerodt reaction. Morpholine is a six-membered ring containing oxygen and nitrogen, and its alkalinity is much lower than that of its parent piperidine. The marketed morpholine drugs are mainly distributed in the fields of tumors, cardiovascular and cerebrovascular diseases, respiratory system diseases, digestive system diseases, infectious diseases and mental disorders.