Skunk defensive secretion is composed of seven major volatile components. These can be divided into two major groups of compounds, thiols and acetate derivatives of these thiols. Two of the thiols are responsible for the strongly repellent odor of the secretion, (E)-2-butene-1-thiol and 3-methyl-1-butanethiol. Had enough of a chemistry equation for the day? Read about Babbs and skunks and why “Oh-dee-skunk” parfume permeates about two miles of what was once fresh air around your nose.