Eucalyptol is a bicyclic epoxy monoterpene, and, more precisely, a limonene oxide.
C10 H18 O
hard to dissolve in water
This essential oil may be detected in larger quantities (approx. 85%) in eucalyptus, from which its name is derived, but also in hemp, mint, sage, thyme, basil, and the tea tree.
Since eucalyptol has an expectorant and bactericidal effect, it is mainly used to alleviate respiratory problems.