Carbon-11 is undoubtedly an attractive PET radiolabeling synthon because carbon is present in all biological molecules. It is mainly found under ¹¹CO₂, but the latter being not very reactive, it is necessary to convert it into a secondary precursor. ¹¹CO is an attractive precursor for labeling the carbonyl position through transition-metal mediated carbonylation because of its access to a wide range of functional groups (e.g., amides, ureas, ketones, esters, and carboxylic acids) present in most PET tracer molecules. However, the main limitations of ¹¹CO labeling are the very short half-life of the radioisotope carbon-11 and its low concentration, and the low reactivity and poor solubility of ¹¹CO in commonly used organic solvents. In this work, we show that a possible solution to these limitations is to use microfluidic reactor technology to perform carbonylation reactions, whilst a novel approach to generate CO from CO₂ by plasma is described. The methodology consists of the decomposition of CO₂ into CO by non-thermal DBD plasma at room temperature and atmospheric pressure, followed by the total incorporation of CO thus formed in the gas phase by carbonylation reaction, in less than 2 min of residence time. This “proof of principle” developed in carbon-12 would be further applied in carbon-11. Although considerable advances in ¹¹CO chemistry have been reported in recent years, its application in PET tracer development is still an area of work in progress, because of the lack of commercially available synthesis instruments designed for ¹¹C-carbonylations. To the best of our knowledge, such an innovative and efficient process, combining microfluidics and plasma, allowing the very fast organic synthesis of carbonyl molecules from CO₂ with high yield, in mild conditions, has never been studied.

中文翻译：

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使用等离子气/液微反应器从二氧化碳中快速进行羰基化反应，用于放射性标记

碳11无疑是有吸引力的PET放射性标记合成子，因为碳存在于所有生物分子中。它主要在¹¹ CO ₂下发现，但后者反应性不是很高，因此有必要将其转化为次级前驱体。¹¹ CO是一种有吸引力的前体，可通过过渡金属介导的羰基化作用标记羰基位置，因为它可与大多数PET示踪剂分子中存在的各种官能团（例如酰胺，脲，酮，酯和羧酸）接触。然而，主要限制¹¹ CO标记是放射性同位素碳11和其低浓度的非常短的半衰期，且反应性低的溶解性差¹¹常用有机溶剂中的CO。在这项工作中，我们表明解决这些局限性的一种可能方法是使用微流体反应器技术进行羰基化反应，同时介绍了一种通过等离子体从CO ₂生成CO的新颖方法。该方法包括在室温和大气压下通过非热DBD等离子体将CO ₂分解为CO ，然后在不到2分钟的停留时间内将通过羰基化反应在气相中形成的CO完全掺入。碳12中开发的这种“原理证明”将进一步应用于碳11中。尽管¹¹取得了长足的进步近年来已经报道了CO化学，由于缺乏设计用于¹¹ C-羰基化的市售合成仪器，其在PET示踪剂开发中的应用仍在研究中。据我们所知，这种创新而有效的方法结合了微流体技术和等离子体技术，可以在温和的条件下以高收率非常快速地从CO ₂有机合成羰基分子。