Neocarboxylic Acids

Neocarboxylic Acids. The acid-catalyzed carboxylation of alkenes with carbon monoxide in the presence of water is used commercially to produce neocarboxylic acids.82 Pivalic acid from isobutylene is the most important product. A number of 

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The reaction is also called hydrocarboxylation. According to a later modification, the alkene first reacts with carbon monoxide in the presence of the acid to form an acyl cation, which then is hydrolyzed with water to give the carboxylic acid.97 The advantage of this two-step synthesis is that it requires only medium pressure (100 atm). Aqueous HF (85-95%) gave good results in the carboxylation of alkenes and cycloalkenes.98 Phosphoric acid is also effective in the carboxylation of terminal alkenes and isobutylene, but it causes substantial oligomerization as well.99 100 Neocarboxylic acids are manufactured industrially with this process (see Section 7.2.4). The addition may also be performed with formic acid as the source of CO (Koch-Haaf reaction).101 102 The mechanism involves carbocation formation via protonation of the alkene97 103 [Eq. (7.10)]. It then reacts with carbon monoxide... 

Carboxylation of Alkanes and Alkenes. When alkenes react with carbon monoxide and water in the presence of strong mineral acids at elevated temperature and pressure, carboxylic acids are formed (87,88). The transformation is called the Koch reaction and may also be considered as hydrocarboxylation (eq. 61). Neocarboxylic acids with high selectivities are manufactured industrially with this process applying mixed Bronsted and Lewis acid catalysts (H2SO4, H3PO4, HF, and SbFg, BFg). 

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