The Catalytic Effect of Fluoroalcohol Mixtures Depends on Domain Formation
The Catalytic Effect of Fluoroalcohol Mixtures Depends on Domain Formation
复制标题
DOI：
10.1021/acscatal.6b03090
复制
发表时间：
2017-03-01
期刊：
影响因子：
12.9
通讯作者：
Kirchner, Barbara
中科院分区：
文献类型：
--
作者：
Holloczki, Oldamur;Berkessel, Albrecht;Kirchner, Barbara
在本文中，我们通过分子动力学模拟研究了1，1，1，3，3，3-六氟-2-丙醇(HFIP)与H_2O_2水溶液的催化活性混合物。很明显，HFIP分子与过氧化氢强烈结合，这是发生所需催化反应所必需的。当底物环辛烯加入到溶液中时，这种相互作用得到加强，这表明碳氢化合物的存在提高了催化活性。我们可以清楚地观察到混合物的微观非均相结构，这是羟基、水和H_2O_2从氟化的烷基部分以大区域的形式分离的结果，这些区域跨越了系统的大范围。然而，碳氢化合物不适合这两个微相中的任何一个，它在宏观上均相的液体中形成单独的聚集体，从而形成三亲混合物。后一种聚集体大多被氟部分包围，因此，H_2O_2必须从极性转移到氟域才能与环辛烯反应。因此，本反应应形象地描述为相转移或界面反应，而不是均相液相过程。
In the present contribution, we investigated catalytically active mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and aqueous H2O2 by molecular dynamics simulations. It is clearly observable that the HFIP molecule strongly binds to the H2O2, which is necessary for the desired catalytic reaction to occur. Upon the addition of the substrate cyclooctene to the solution, this interaction is enhanced, which suggests that the catalytic activity is increased by the presence of the hydrocarbon. We could clearly observe the microheterogeneous structure of the mixture, which is the result of the separation of the hydroxyl groups, water, and H2O2 from the fluorinated alkyl moiety in the form of large domains, which span through large areas of the system. The hydrocarbon, however, does not fit into either one of these two microphases, and it forms separate aggregates in the macroscopically homogeneous liquid, creating thereby a triphilic mixture. The latter kinds of aggregates are mostly surrounded by the fluorous moieties, and therefore, the H2O2 has to move from the polar through the fluorous domain to be able to react with the cyclooctene. Accordingly, the present reaction should be described figuratively as a phase transfer or an interfacial reaction, rather than a homogeneous liquid-phase process.