Reactivity and activation of dioxygen-derived species in aprotic media (a model matrix for biomembranes).
Reactivity and activation of dioxygen-derived species in aprotic media (a model matrix for biomembranes).
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非质子介质（生物膜的模型矩阵）中双氧衍生物质的反应性和活化。
DOI：
10.1098/rstb.1985.0159
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
M. S. Mcdowell
中科院分区：
文献类型：
--
作者：
D. T. Sawyer;J. Roberts;T. Calderwood;H. Sugimoto;M. S. Mcdowell
在非质子介质中，氧的电化学还原生成超氧离子(O2-)，它是一种有效的Brnsted碱、亲核剂、单电子还原剂和还原过渡金属离子的单电子氧化剂。在亲电底物(有机卤化物和羰基)上，O2-取代离开基团形成过氧基(Roo.)在最初的过程中。超氧离子氧化抗坏血酸、儿茶酚、吩嗪和氢黄素的活化氢原子。O2-与1，2-二苯肼结合生成偶氮苯的阴离子自由基，后者与O2反应生成偶氮苯和O2-(O2-诱导的自氧化反应的一个例子)。在苯肼的作用下，O2-产生苯基。HO2的原位生成。(O2-加上质子源)导致从烯丙基和其他具有弱杂原子的基团中提取H原子--H键(结合能(B.E.)小于335千焦耳)。这是一个与HO2简单的二级歧化反应竞争的过程。对H_2O_2和O_2(Kbi在Me2SO中约等于10(4)摩尔~(-1)S~(-1))。在干乙腈的过氧化氢溶液中加入[FeII(MeCN)4](ClO4)2，可通过初始形成加合物[FeII(H2O2)2+-Fe(O)(H2O)2+]催化过氧化氢的快速歧化反应，从而将第二个过氧化氢氧化为氧气。在有机底物如1，4-环己二烯、1，2-二苯基肼、儿茶酚和硫醇的存在下，FeII-H_2O_2/MeCN体系产生脱氢产物；与醇、醛、甲基苯乙烯、硫醚、硫氧化物和膦形成FeII(H_2O_2)~(2+)加合物促进它们的单氧合。FeO_2~+-H_2O_2反应的产物[FeII(H_2O_2)_2~(2+)]与单线态氧(1O_2)的化学组成非常相似，这已被二苯基异苯并呋喃、9，10-二苯基菲、Rubrene和富电子的不饱和碳-碳键(Ph2C=CPh2，PhC=CPH和cis-PhCH=CHPh)的化学计量比二氧氧化所证实。在无配体的乙腈(MeCN)中，无水三氯化铁(FeIIICl3)能有效地催化过氧化氢的环氧化反应。FeIIICl3进一步催化生成的环氧化物二聚为二恶烷。这些观察表明，配位不饱和的强Lewis酸，[FeII(MeCN)4]2+和[FeIIICl3]，能激活H_2O_2形成有效的氧化和脱氢试剂。
In aprotic media the electrochemical reduction of dioxygen yields superoxide ion (O2-), which is an effective Brønsted base, nucleophile, one-electron reductant, and one-electron oxidant of reduced transition metal ions. With electrophilic substrates (organic halides and carbonyl carbons) O2- displaces a leaving group to form a peroxy radical (ROO.) in the primary process. Superoxide ion oxidizes the activated hydrogen atoms of ascorbic acid, catechols, hydrophenazines and hydroflavins. Combination of O2- with 1,2-diphenylhydrazine yields the anion radical of azobenzene, which reacts with O2 to give azobenzene and O2- (an example of O2--induced autoxidation). With phenylhydrazine, O2- produces phenyl radicals. The in situ formation of HO2. (O2- plus a proton source) results in H-atom abstraction from allylic and other groups with weak heteroatom--H bonds (binding energy (b.e.) less than 335 kJ). This is a competitive process with the facile second-order disproportionation of HO2. to H2O2 and O2 (kbi approximately equal to 10(4) mol-1 s-1 in Me2SO). Addition of [FeII(MeCN)4] (ClO4)2 to solutions of hydrogen peroxide in dry acetonitrile catalyses a rapid disproportionation of H2O2 via the initial formation of an adduct [FeII(H2O2)2+----Fe(O)(H2O)2+], which oxidizes a second H2O2 to oxygen. In the presence of organic substrates such as 1,4-cyclohexadiene, 1,2-diphenylhydrazine, catechols and thiols the FeII-H2O2/MeCN system yields dehydrogenated products; with alcohols, aldehydes, methylstyrene, thioethers, sulphoxides, and phosphines, the FeII(H2O2)2+ adduct promotes their monoxygenation. The product from the FeO2+-H2O2 reaction, [FeII(H2O2)22+], exhibits chemistry that is closely similar to that for singlet oxygen (1O2), which has been confirmed by the stoichiometric dioxygenation of diphenylisobenzofuran, 9,10-diphenylanthracene, rubrene and electron-rich unsaturated carbon-carbon bonds (Ph2C = CPh2, PhC = CPh and cis-PhCH = CHPh). In dry ligand-free acetonitrile (MeCN), anhydrous ferric chloride (FeIIICl3) activates hydrogen peroxide for the efficient epoxidation of alkenes. The FeIIICl3 further catalyses the dimerization of the resulting epoxides to dioxanes. These observations indicate that strong Lewis acids that are coordinatively unsaturated, [FeII(MeCN)4]2+ and [FeIIICl3], activate H2O2 to form an effective oxygenation and dehydrogenation agent.(ABSTRACT TRUNCATED AT 400 WORDS)