What is PBO and Where Does it Come From?

Piperonyl butoxide (PBO), 2-(2-butoxyethoxy)ethyl 6-propyl-piperonyl ether (IUPAC), is an insecticide synergist produced from the condensation of the sodium salt of 2-(2-butoxyethoxy) ethanol and the chloromethyl derivative of hydrogenated safrole.  The methylenedioxyphenyl moiety constitutes over half of the PBO molecule by weight and is either derived from sassafras oil or produced by a synthetic route.