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Researchers at the University of Toronto's department of chemistry have discovered catalysts made from iron that might replace the platinum metals typically used in industrial chemical processes to produce drugs, fragrances and flavors. The study was published in Chemistry on Apr. 9, 2009. According to the report, metals such as ruthenium, rhodium and palladium are more expensive and toxic than iron.
If the catalysts such as ruthenium, rhodium and palladium are toxic, then costly purification techniques must be used to remove any toxicity from the synthesized product. Iron has has been considered to be a "base metal" of low catalytic activity; therefore, some might be surprised by its successful use.
The key to producing the iron catalyst was to prepare a complex of iron with a structure similar to the most active ruthenium catalyst. Chemical catalysts are generally known for their ability to speed up a reaction but they can also influence the structure of the chemical that is produced in that reaction.
Catalysts used in the synthesis of a chemical used as a drug or fragrance are most valuable when they cause the production of the chemical in one structural form and not the mirror image of that form (i.e., producing a left-handed form and not the right-handed one).
The catalyst was made by attaching to iron, in its "ferrous" state, an organic molecule that contains carbon, hydrogen, phosphorus and nitrogen with the atoms arranged in an exclusively right-handed structural form. The catalyst is used in small amounts to convert a large amount of inexpensive ketone to a large amount of the valuable alcohol product in just the left-handed form. This process is called asymmetric transfer hydrogenation.