Coumarin, molecular formula: C9H6O2, relative molecular weight 146.15, white crystalline solid, melting point 68 ~ 70 ° C, boiling point 298°C/266Pa, relative density 0.9350. It is naturally found in black fragrant beans, cockleburs, wild vanilla, orchids, and has fresh hay and fragrant fragrant incense. In general, it is not edible, and tobacco and external use are allowed. On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization has initially compiled and referenced, and coumarin is in the list of 3 types of carcinogens.
