Among the amines that have been systematically applied for CO₂ capture, several alkanolamines have been proved to be very effective. Although the formation of carbamates – the reaction product of CO₂ and the amine group – is recognized as the most important process, the behavior of a tertiary alkanolamine cannot be explained, because a carbamate cannot be formed. In such a case, the formation of a monoalkyl carbonate (MAC) – a hemiester of carbonic acid and the alcohol group of the alkanolamine – is the most important process. In the present study, we demonstrate that the MAC is formed not only for tertiary alkanolamines, but also for the simpler ones, and that this reaction takes place even in aqueous medium. The species were detected by ¹³C NMR, which allowed the estimation of the formation constant of MACs for choline, triethanolamine, diethanolamine, and monoethanolamine as 0.44, 2.6, 0.72, and 0.66, respectively. These values are similar to those ones for MACs of aliphatic alcohols and sugars. Although the formation constants are much higher for carbamates, MAC formation becomes a more significant process as the pH is lowered during CO₂ capture. A brief review of previous works demonstrated that MACs could be detected in other experiments whether the authors would aware of this class of compounds.

在已经系统地用于CO ₂捕集的胺中，几种链烷醇胺已被证明是非常有效的。尽管公认氨基甲酸酯的形成（CO ₂和胺基的反应产物）是最重要的过程，但由于不能形成氨基甲酸酯，因此无法解释叔链烷醇胺的行为。在这种情况下，最重要的过程是碳酸单烷基酯（MAC）（碳酸的半酯和链烷醇胺的醇基）的形成。在本研究中，我们证明MAC不仅形成叔链烷醇胺，而且形成简单链烷醇胺，而且该反应即使在水性介质中也会发生。该物种被¹³人发现13 C NMR可以估算出胆碱，三乙醇胺，二乙醇胺和一乙醇胺的MACs形成常数分别为0.44、2.6、0.72和0.66。这些值类似于脂族醇和糖的MAC值。尽管氨基甲酸酯的形成常数要高得多，但随着CO ₂捕获过程中pH降低，MAC的形成变得更为重要。简要回顾以前的研究表明，在作者们是否会意识到此类化合物的情况下，可以在其他实验中检测到MAC。