Safrole is a phenylether (Figure l) which occurs as a component of the volatile oil in many plant species. In its pure form, it is a mobile liquid with a camphoraceous aroma at ambient temperature.
The earliest extensive use of natural safrole was as a flavoring for root beer and sasparilla beverages in the United States, but this was discontinued in 1958, Another early application was as a fragrancing agent in a range of products which include floor waxes, soaps, glues and disinfectants.
Today, the two major outlets for natural safrole lie in its chemical conversion to heliotropine, a fragrance compomd, and piperonyl butoxide (PBO). The latter plays a critical role as a synergist for natural pyrethrum-based insecticides which alone are much less effective. In several countries, natural pyrethrum/PBO mixtures are the only formulations permitted for use in food stores and food processing industries. Demand is growing also in the retail insecticide market owing to the ‘soft’ (biodegradable) characteristics and ‘green’ image of these mixtures.
