Rearrangements wonât occur if the initially formed carbocation is the most thermodynamically stable out of all the possible isomers. For example, if you use t-butyl bromide in a Friedel-Crafts alkylation, it will not rearrange, since the t-butyl c... This page may be out of date. Save your draft before refreshing this page.
Platinum was first used for minting coins in Spanish-colonized America. Following the discovery of platinum in gold rocks, the Spaniards were unable to use it for a long time because they had no technology for processing this metal.latinum was first used for minting coins in Spanish-colonized America. Following the discovery of platinum in gold rocks, the Spaniards were unable to use it for a long time because they had no technology for processing this metal.
There are 4 platinum alloys commonly used in the USA. 1  Pt900/Ir = 900 parts platinum, 100 parts Iridium. 2  Pt950/Ir = 950 parts platinum, 50 parts Iridium. 3  Pt950/Ru = 950 parts platinum, 50 parts Ruthenium.  Pt950/Co = 950 parts platinum, 50 parts Cobalt.