Phenol–phenoxyl radical equilibria by electron spin resonance: are radicals derived from tocopherol and analogues exceptionally stabilized?
作者:Richard A. Jackson、Kamran Mousavi Hosseini
DOI:10.1039/c39920000967
日期:——
The extra âstabilizationâ of the 2,2,4,6,7-pentamethyl-2,3-dihydrobenzofuran-5-oxyl radical compared with the 2,6-ditert-butyl-4-methoxyphenoxyl radical is attributed to entropy differences between the parent phenols.
substituents and their contribution to the O−H bond dissociation enthalpy (BDE) in phenolic compounds. A series of ortho- and para-(S,Se,Te)R-substituted phenols were prepared and investigated by EPR, IR, and computational methods. Substituents lowered the O−H BDE by >3 kcal/mol in the para position, while the ortho-effect was modest due to hydrogenbonding (∼3 kcal/mol) to the O−H group.
关于有机硫属元素取代基的ED / EW特性及其对酚类化合物中O-H键离解焓(BDE)的贡献知之甚少。制备了一系列邻-和对-(S,Se,Te)R取代的酚,并通过EPR,IR和计算方法进行了研究。取代基降低了O - H BDE由> 3千卡/摩尔在对位位置,而邻-效应是氢键适度由于(〜3千卡/摩尔)向O-H基团。
Reaction of superoxo Co(III) complex with stable phenoxy radicals
作者:A. Nishinaga、H. Tomita、T. Matsuura
DOI:10.1016/s0040-4039(00)78701-6
日期:1980.1
A typical superoxocomplex [Co(CN)5O2][Ph3PNPPh3]3 combines with stable phenoxy radicals in CH2Cl2 leading to selective formation of peroxy--quinols except for 2,4,6-tri--butylphenoxy radical, representing radical reactivity of the complex.
Aryl Oxalate Derivatives as Convenient Precursors for Generation of Aryloxyl Radicals
作者:Paul M. Lahti、David A. Modarelli、Frank C. Rossitto、Ahmet Levent Inceli、Andrew S. Ichimura、Shyamala Ivatury
DOI:10.1021/jo951696v
日期:1996.1.1
oxalates (DAOs) for unimolecular generation of phenoxyl-based radicals under solution and rigid matrix conditions is described. AOCs are usable for photochemical generation of phenoxyl radicals, but are only conveniently stable as precursors when 2,6-di-tert-butylated derivatives are used. AOBs may be used as thermal precursors to aryloxylradicals, since they typically decompose within 2-3 h at 60-85 degrees
描述了在溶液和刚性基质条件下使用芳氧基草酰氯(AOC),芳氧基草酰叔丁基过氧化物(AOB)和草酸二芳基酯(DAO)来单分子生成苯氧基基团的现象。AOC可用于光化学生成苯氧基自由基,但仅当使用2,6-二叔丁基化衍生物时,才能方便地稳定用作前体。AOB可用作芳氧基的热前体,因为它们通常会在60-85摄氏度下2-3小时内分解以产生酚。(1)H-NMR溶液动力学研究发现,对于苯氧基草酰叔丁基过氧化物的分解,DeltaH()= 31 kcal / mol,DeltaS()= +3.4 cal / mol-K,这与过氧化物键断裂的基本一致一致。AOB和更稳定的DAO也是方便的光化学苯氧基自由基前体。
Convenient unimolecular sources of aryloxyl radicals I -- aryloxyoxalyl chlorides
作者:David A. Modarelli、Frank C. Rossitto、Paul M. Lahti
DOI:10.1016/s0040-4039(01)80721-8
日期:1989.1
UV photolysis of readily synthesized aryloxyoxalyl chloride half-esters provides a new unimolecular source of aryloxylradicals, as shown by ESR and UV-vis spectroscopy.