Indole is a colorless crystalline solid with a weak naphthalene odor. It is readily soluble in most organic solvents, hot water, liquid ammonia. It molecule has a planar structure. Indole is a weak base. Natural jasmine oil, used in the perfume industry, contains around 2.5% of indole. Indole structure is a motif in nature. Prominent examples include tryptophan (aromatic side chain amino acid), serotonin (neurotransmitter), auxin (plant growth hormone), and indigo (plant colorant), melatonin, bufotanine.
Indole is produced by coal tar processing;
by dehydrogenation of o-ethylaniline with following cyclyzation;
as a perfumery fixer;
in the preparation of bioactive compounds (hormones, hallucinogens, tryptophan, auxin) and pharmaceuticals (e.g. indometacin);
to produce selective herbicides;
in making perfumes, dyes and agrochemicals;