Bismuth(III) Derivatives: New Catalysts

Since the beginning of the 1980s, the use of bismuth(III) derivatives as catalysts in organic synthesis has increased considerably. This new interest in bismuth is easily justified by its friendly ecological behavior. Bismuth is a relatively rare metal present in the earth's crust at about the same abundance as silver and is almost never found in its native state. It is usually associated with copper, lead, tin, tungsten, silver, and gold ores. Bismuth is the heaviest of the heavy metals and the only non-toxic heavy metal. Bismuth catalysts are used in industry for the production of acrylonitrile and acrolein. The catalytic properties of bismuth(III) compounds have been investigated during the past twenty years. Applications of bismuth(V) in organic chemistry are also well known. Although these reactions typically involve bismuth(III) halides (BiX₃ where X = F, Cl, Br, I), bismuth(III) trifluoromethanesulfonate (Bi(OTf)₃) have also been discovered recently in numerous reactions. The main advantages of using these catalysts are their strong activities and their low cost with respect to most other known catalysts, and their easy removal by filtration, simplifying the purification of the product.