德国海德堡大学Peter Comba课报道了天然非生物铁氧化介导环境重要的甲基取代底物生成C1和C2化合物。相关研究成果发表在2023年11月6日出版的《美国化学会杂志》。

含有一个碳原子（C1）的有机和无机挥发性化合物，如二氧化碳、甲烷、甲醇、甲醛、一氧化碳和氯甲烷，在环境中普遍存在，是全球碳循环的关键成分，在大气物理和化学中发挥重要作用，如温室气体，破坏平流层和对流层臭氧，并控制大气氧化能力。到目前为止，环境中的大多数C1化合物都与生物体内复杂的代谢和酶促途径或有机物的燃烧过程有关。

该文中，研究人员提出了令人信服的证据，证明许多C1和C2化合物在甲基取代的底物的甲基中有共同的来源，这些底物通过氧化铁介导的甲基自由基的形成而裂解。该场景源于以机理研究良好的二苯胺氧化铁络合物作为氧化剂，二甲基亚砜作为环境相关模型基质的实验，并得到了基于密度泛函理论和从头算量子化学研究的计算建模的支持。详尽的实验模型研究也涉及广泛的同位素标记，并用与环境相关的氧化铁取代了联苯胺模型系统，最后是一组具有不同铁和有机物含量的土壤。所有数据的组合表明，氧化铁介导的由甲基取代的底物形成甲基自由基是环境中广泛存在的C1和C2化合物的常见非生物来源。

附：英文原文

Title: Natural Abiotic Iron-Oxido-Mediated Formation of C1 and C2 Compounds from Environmentally Important Methyl-Substituted Substrates

Author: Jonas Hdeler, Gunasekaran Velmurugan, Rebekka Lauer, Rejith Radhamani, Frank Keppler, Peter Comba

Issue&Volume: November 6, 2023

Abstract: Organic and inorganic volatile compounds containing one carbon atom (C1), such as carbon dioxide, methane, methanol, formaldehyde, carbon monoxide, and chloromethane, are ubiquitous in the environment, are key components in global carbon cycling, play an important role in atmospheric physics and chemistry, e.g., as greenhouse gases, destroy stratospheric and tropospheric ozone, and control the atmospheric oxidation capacity. Up to now, most C1 compounds in the environment were associated with complex metabolic and enzymatic pathways in organisms or to combustion processes of organic matter. We now present compelling evidence that many C1 and C2 compounds have a common origin in methyl groups of methyl-substituted substrates that are cleaved by the iron oxide-mediated formation of methyl radicals. This scenario is derived from experiments with a mechanistically well-studied bispidine-iron-oxido complex as oxidant and dimethyl sulfoxide as the environmentally relevant model substrate and is supported by computational modeling based on density functional theory and ab initio quantum-chemical studies. The exhaustive experimental model studies, also involving extensive isotope labeling, are complemented with the substitution of the bispidine model system by environmentally relevant iron oxides and, finally, a collection of soils with varying iron and organic matter contents. The combination of all data suggests that the iron oxide-mediated formation of methyl radicals from methyl-substituted substrates is a common abiotic source for widespread C1 and C2 compounds in the environment.

DOI: 10.1021/jacs.3c06709

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.3c06709