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Selective Esterification of Phosphonic Acids
Molecules ( IF 4.6 ) Pub Date : 2021-09-17 , DOI: 10.3390/molecules26185637
Damian Trzepizur 1 , Anna Brodzka 1 , Dominik Koszelewski 1 , Ryszard Ostaszewski 1
Affiliation  

Here, we report straightforward and selective synthetic procedures for mono- and diesterification of phosphonic acids. A series of alkoxy group donors were studied and triethyl orthoacetate was found to be the best reagent as well as a solvent for the performed transformations. An important temperature effect on the reaction course was discovered. Depending on the reaction temperature, mono- or diethyl esters of phosphonic acid were obtained exclusively with decent yields. The substrate scope of the proposed methodology was verified on aromatic as well as aliphatic phosphonic acids. The designed method can be successfully applied for small- and large-scale experiments without significant loss of selectivity or reaction yield. Several devoted experiments were performed to give insight into the reaction mechanism. At 30 °C, monoesters are formed via an intermediate (1,1-diethoxyethyl ester of phosphonic acid). At higher temperatures, similar intermediate forms give diesters or stable and detectable pyrophosphonates which were also consumed to give diesters. 31P NMR spectroscopy was used to assign the structure of pyrophosphonate as well as to monitor the reaction course. No need for additional reagents and good accessibility and straightforward purification are the important aspects of the developed protocols.

中文翻译:

膦酸的选择性酯化

在这里,我们报告了膦酸单酯化和二酯化的直接和选择性合成程序。研究了一系列烷氧基供体,发现原乙酸三乙酯是进行转化的最佳试剂和溶剂。发现了对反应过程的重要温度影响。取决于反应温度,以合适的产率专门获得膦酸的单乙酯或二乙酯。所提出的方法的底物范围在芳香族和脂肪族膦酸上得到验证。所设计的方法可成功应用于小规模和大规模实验,而不会显着降低选择性或反应收率。进行了几次专门的实验以深入了解反应机理。在 30 °C 时,单酯通过中间体(膦酸的 1,1-二乙氧基乙酯)形成。在更高的温度下,类似的中间体形式产生二酯或稳定且可检测的焦膦酸盐,它们也被消耗以产生二酯。31 P NMR 光谱用于确定焦膦酸酯的结构并监测反应过程。不需要额外的试剂、良好的可及性和直接的纯化是所开发协议的重要方面。
更新日期:2021-09-17
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