作者:Markus Griesser、Jean-Philippe R. Chauvin、Derek A. Pratt
DOI:10.1039/c8sc02400f
日期:——
thiols (∼107 M−1 s−1) and sulfenic acids (∼109 M−1 s−1). Importantly, since sulfinic and sulfenic acids are very strong H-bond donors (αH2 ∼ 0.63 and 0.55, respectively), their reactivity is greatly attenuated in H-bond accepting solvents, whereas the reactivity of thiols is largely solvent-independent. Efforts to measure rate constants for the reactions of sulfinic acids with alkylperoxyl radicals were
亚磺酸(RSO 2 H)因其容易自氧化而成为困难的试剂而闻名。然而,近来它们已在各种有用的自由基链反应中用作关键试剂。为了解决这一矛盾,并使使用亚磺酸的自由基反应得以进一步发展,我们首次表征了其H原子转移反应的热力学和动力学。通过自由基平衡确定亚磺酸的OH键离解焓(BDE)为〜78 kcal mol -1;大致中途的RS-H BDE在硫醇(~87千卡mol之间-1)和RSO-H BDE在次磺酸(约70千卡摩尔-1)。无论如何,RSH,RSOH和RSO 2H与烷基具有相对相似的固有H原子转移反应性(〜10 6 M -1 s -1)。与直觉相反,具有更多反应性烷氧基的速率常数趋势遵循反应能量:RSO 2 H约为10 8 M -1 s -1,硫醇(约10 7 M -1 s -1)和亚硫酸之间(〜10 9 M -1 s -1)。重要的是,由于亚和次磺酸都非常强的氢键供体(α ħ 2分别为约0.63和0