In many organic compounds, Indole structures can be found, such as an essential amino acid for animals and tryptophan-containing proteins, auxin (indole-3-acetic acid), anti-inflammatory drugs, indomethacin The vasodilators, alkaloids and pigments also contain a quinone structure, which is a natural alkaloid widely found in nature, and has a wide range of biological activities such as antibacterial, antitumor and antiviral.
The name of the indole is composed of indigo (lanthanide dye) and oleum (fuming sulphuric acid) because yttrium is first produced by mixing indigo and fuming sulfuric acid.
One-step synthesis of indole from aniline and ethylene glycol is currently the most economical of many synthetic methods.