Enhancing the deperoxidation activity of cobalt(II)acetylacetonate by the addition of octanoic acid

摘要

The homolytic scission of peroxides with catalytic amounts of cobalt(II) complexes is used in several industrial oxidation processes. In this contribution, we report that addition of small amounts of octanoic acid significantly enhances the catalytic deperoxidation activity of the cobalt(II)acetylacetonate complex. We attribute this to the stabilization of the Co?￡?OOR bond upon coordination of octanoic acid, preventing the unimolecular scission. As such, the cobalt peroxo intermediate is forced to enter an alternative catalytic cycle which causes its rapid conversion to the highly reactive cobalt hydroxy. This shift in catalytic cycle results in a higher pre-exponential rate factor, over-compensating the higher barrier of the new rate-determining step. Kinetic bOAst: The catalytic cycle by which Co(acac)_2 decomposes alkyl hydroperoxide can be tuned by the addition of octanoic acid (OA). Coordination of OA stabilizes the Co?￡ ?OOR bond and prevents unimolecular scission. As such, the CoOOR species are forced to enter an alternative catalytic cycle, which results in a higher pre-exponential rate factor, over-compensating the higher barrier of the new rate-determining step.