ABSTRACT
The isolation depends upon gentle methods for obtaining the components without isomerization by heating and distillation. For the isolation of pure quassin and neoquassin, the wood is powdered and extracted three times with hot water, tannins are precipitated with lead acetate, charcoal added to absorb the quassins, and these are then leached from the dried charcoal with chloroform. The group by far represents the bulk of substances of natural origin used as pesticides, including the commercially important pyrethrins and rotenoids, the formerly important nicotine and quassin. Historically the work breaks into two periods, those few isolations done by classical isolation methods and those done with the aid of gas chromatography and its allied techniques. Methods for pheromone isolation could therefore be a catalog of all chemical isolation techniques, but in practice, the great mass of work has been carried out on volatile compounds, including that work which has been done on mammalian pheromones.
