Carbonylation of Isobutylene

The addition of carhon monoxide to isobutylene under high pressures and in the presence of an acid produces a carhon monoxide-olefin complex, an acyl carhocation. Hydrolysis of the complex at lower pressures yields neopentanoic acid  

Neopentanoic acid (trimethylacetic acid) is an intermediate and an ester-ifying agent used when a stable neo structure is needed. 

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