Hermans Ive, Peeters Jozef, Jacobs Pierre A
K.U.Leuven, Department of Chemistry, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
Chemphyschem. 2006 May 12;7(5):1142-8. doi: 10.1002/cphc.200600074.
Herein, we demonstrate that the chain-initiating dissociation of cyclohexyl hydroperoxide, CyOOH, is substantially accelerated by H-bond acceptors (e.g. Teflon), which assist O-O bond breaking by stabilising the leaving *OH radical. This is a completely new approach to boost the chain-propagating radical concentration. Indeed, up to now, literature has remained focussed on transition metal catalysis. In addition to this initiation effect, we demonstrate how inert perfluorinated compounds are also able to steer the selectivity at the molecular level, by promoting the conversion of the intermediate cyclohexyl hydroperoxide to the most desired end-product, cyclohexanone. This effect is explained by an enhanced, H-bond-assisted, hydroperoxide propagation. This hitherto overlooked hydroperoxide propagation was recently presented by us as the dominant cyclohexanone and cyclohexanol source. We herein thus confirm our previously reported autoxidation scheme, and illustrate its usefulness as a solid basis for designing new catalytic systems.
在此,我们证明了氢过氧化环己烷(CyOOH)的链引发解离会被氢键受体(如聚四氟乙烯)显著加速,氢键受体通过稳定离去的*OH自由基来协助O - O键断裂。这是提高链增长自由基浓度的全新方法。事实上,到目前为止,文献一直聚焦于过渡金属催化。除了这种引发效应外,我们还证明了惰性全氟化合物如何通过促进中间体氢过氧化环己烷向最期望的终产物环己酮的转化,在分子水平上控制选择性。这种效应可通过增强的、氢键辅助的氢过氧化物传播来解释。这种迄今为止被忽视的氢过氧化物传播最近被我们提出是环己酮和环己醇的主要来源。我们在此确认了我们之前报道的自氧化方案,并说明了其作为设计新催化体系坚实基础的实用性。