Direct observation of vinyl hydroperoxide
Direct observation of vinyl hydroperoxide
复制标题
DOI：
10.1039/c5cp02917a
复制
发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Lester, Marsha I.
中科院分区：
文献类型：
--
作者：
Liu, Fang;Fang, Yi;Lester, Marsha I.
预计许多烷基取代的Criegee中间体经历分子内1，4-氢转移以形成异构的乙烯基过氧化氢物质（C=COOH部分），其断裂以释放OH和乙烯氧基自由基。我们报告通过羧酸催化的Criegee中间体的互变异构化形成的稳定的乙烯基过氧化氢的直接检测。Criegee中间体和羧酸之间的双氢键相互作用通过双氢转移促进有效的氢转移。甲酸或乙酸的氘化允许D原子迁移以产生部分氘化的乙烯基氢过氧化物，其在质量上不同于CH 3CHOO、（CH 3）（2）COO和CH 3CH 2CHOO Criegee中间体。使用10.5 eV的光电离，三个原型的乙烯基氢过氧化物，CH 2 =CHOOD，CH 2 =C（CH 3）OOD，和CH 3 CH =CHOOD，直接检测。互补电子结构计算揭示了几种反应途径，包括无障碍酸催化的互变异构反应预测先前和无障碍加成反应，产生氢过氧烷基甲酸酯。
Many alkyl-substituted Criegee intermediates are predicted to undergo an intramolecular 1,4-hydrogen transfer to form isomeric vinyl hydroperoxide species (C=COOH moiety), which break apart to release OH and vinoxy radicals. We report direct detection of stabilized vinyl hydroperoxides formed via carboxylic acid-catalyzed tautomerization of Criegee intermediates. A doubly hydrogen-bonded interaction between the Criegee intermediate and carboxylic acid facilitates efficient hydrogen transfer through a double hydrogen shift. Deuteration of formic or acetic acid permits migration of a D atom to yield partially deuterated vinyl hydroperoxides, which are distinguished from the CH3CHOO, (CH3)(2)COO, and CH3CH2CHOO Criegee intermediates by mass. Using 10.5 eV photoionization, three prototypical vinyl hydroperoxides, CH2=CHOOD, CH2=C(CH3)OOD, and CH3CH=CHOOD, are detected directly. Complementary electronic structure calculations reveal several reaction pathways, including the barrierless acid-catalyzed tautomerization reaction predicted previously and a barrierless addition reaction that yields hydroperoxy alkyl formate.