Electronic and Hydrogen Bonding Effects on the Chain-Breaking Activity of Sulfur-Containing Phenolic Antioxidants
作者:Riccardo Amorati、Maria Grazia Fumo、Stefano Menichetti、Veronica Mugnaini、Gian Franco Pedulli
DOI:10.1021/jo060281e
日期:2006.8.1
The effect of the sulfur substituents on the O−H bond dissociation enthalpy values, BDE(O−H), was measured by means of the EPR radical equilibration technique and the reactivity toward peroxyl radicals, kinh, of these phenolic antioxidants was determined by inhibited autoxidation studies. An inverse correlation between these two parameters was found. A p-SMe substituent decreased the BDE(O−H) value
酚的动力学和热力学调查对与含硫(SR) -取代,亚磺酰基(SOR),和磺酰基(SO 2 R)基团和邻报道与含硫基团取代。通过EPR自由基平衡技术测量了硫取代基对OH键离解焓值BDE(OH)的影响,并通过以下方法测定了这些酚类抗氧化剂对过氧自由基的反应活性k inh:抑制了自氧化研究。发现这两个参数之间呈反相关。甲p -SMe取代基的BDE(O-H)的值减小到较小的程度比p-OMe组(-3.6 vs -4.4 kcal / mol),而相同组在邻位的作用则显示相反的趋势(-0.85 vs -0.2 kcal / mol)。后一种结果是根据OH质子与邻位衍生物中的硫或氧取代基之间的分子内氢键强度不同来解释的。通过使硫化物与来自偶氮引发剂AIBN的过氧自由基反应而形成的产物的ESI-MS分析表明,形成了复杂的产物混合物,这可能在确定母体化合物的总体抗氧化活性方面起着重要作用。