Changes in Reactivity as Chemistry Becomes Confined to an Interface. The Case of Free Radical Oxidation of C30H62 Alkane by OH,The Journal of Physical Chemistry Letters

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Changes in Reactivity as Chemistry Becomes Confined to an Interface. The Case of Free Radical Oxidation of C30H62 Alkane by OH
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-02-15 00:00:00 , DOI: 10.1021/acs.jpclett.8b00172
Frances A. Houle ₁ , Aaron A. Wiegel ₁ , Kevin R. Wilson ₁

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We examine in a simple organic aerosol the transition between heterogeneous chemistry under well-mixed conditions to chemistry under interfacial confinement. A single reaction mechanism, shown to reproduce observed OH oxidation chemistry for liquid and semisolid C₃₀H₆₂, is used in reaction–diffusion simulations to explore reactivity over a broad viscosity range. The results show that when internal mixing of the aerosol is fast and the particle interface is enriched in C–H groups, ketone and alcohol products, formed via peroxy radical disproportionation, predominate. As viscosity increases the reactions become confined to a shell at the gas–aerosol interface. The confinement is accompanied by emergence of acyloxy reaction pathways that are particularly active when the shell is 1 nm or less. We quantify this trend using a reaction–diffusion index, allowing the parts of the mechanism that control reactivity as viscosity increases to be identified.

中文翻译：

随着化学反应仅限于界面反应性的变化。OH自由基氧化C ₃₀ H ₆₂烷烃的情况

我们在一个简单的有机气溶胶中研究了在充分混合条件下的非均质化学与在界面约束下的化学之间的过渡。单一反应机理表明，可以再现出所观察到的液态和半固态C ₃₀ H _62的OH氧化化学反应，用于反应扩散模拟，以探索在较宽的粘度范围内的反应性。结果表明，当气溶胶的内部混合快速且颗粒界面富含CH基团时，通过过氧自由基歧化形成的酮和醇产物占主导地位。随着粘度增加，反应会限制在气雾界面处的壳中。该限制伴随着酰氧基反应途径的出现，当壳为1 nm或更小时，该途径特别活跃。我们使用反应扩散指数来量化这种趋势，从而可以确定随着粘度增加而控制反应性的机理部分。

更新日期：2018-02-15

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