Thallium, multiple bonding

Solvatomercuration (40) is a polar addition which follows the Markovnikov rule. Because acetoxymercuric ion is a soft acid, the reaction proceeds facilely. Thallium ions are also soft, hence they attack multiple bonds efficiently. As Tl(III) is also an oxidant, the initial solvatothallation products often undergo rearrangements (41,42) unobserved during solvatomercuration. 

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