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Iridium compounds are used as catalysts in the Cativa process for carbonylation of methanol to produce acetic acid. [92] [93] Iridium complexes are often active for asymmetric hydrogenation both by traditional hydrogenation. [94] and transfer hydrogenation. [95] This property is the basis of the industrial route to the chiral herbicide (S ...
The blue plaque for Smithson Tennant in Finkle Street, Selby, North Yorkshire. Smithson Tennant FRS (30 November 1761 [1] – 22 February 1815 [2]) was an English chemist.He is best known for his discovery of the elements iridium and osmium, which he found in the residues from the solution of platinum ores in 1803.
He is best known as the chemist who discovered the iridium anomaly in the Cretaceous–Paleogene boundary layer that led the team of Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel to propose the Asteroid-Impact Theory, which postulates that an asteroid hit the Earth sixty-five million years ago and caused mass extinction during the ...
Iridium, 77 Ir; Iridium ... History; Discovery and first isolation: Smithson Tennant (1803) Isotopes of iridium. Main isotopes [8] Decay; abundance half-life (t 1/2 ...
The type locality of this iridium anomaly is near Raton, New Mexico. [1] [2]Iridium is a very rare element in the Earth's crust, but is found in anomalously high concentrations (around 100 times greater than normal) in a thin worldwide layer of clay marking the boundary between the Cretaceous and Paleogene periods, 66 million years ago.
In 1880, one John Holland of Cincinnati discovered the ability to melt and make castings of iridium by fusing the white-hot ore with phosphorus, [11] and patented the process in the United States. [12] He invoked the help of Dudley in getting rid of the phosphorus, who did so by repeated applications of lime at great heat.
In 1980, a team of researchers led by Nobel prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Vaughn Michel, discovered that sedimentary layers found all over the world at the Cretaceous–Paleogene boundary (K–Pg boundary, formerly called Cretaceous–Tertiary or K–T boundary) contain a concentration of iridium hundreds of times ...
He is best known for confirming the discovery of chromium by Vauquelin, and for independently discovering iridium in 1803. [1] In 1806, Collet-Descotils misidentified erythronium, a new element discovered in Mexico by Andrés Manuel del Río, thinking that it was chromium. This resulted in Alexander von Humboldt rejecting Del Río's discovery. [2]