- Selective esterification of phosphonic acids
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Here, we report straightforward and selective synthetic procedures for mono-and diesteri-fication 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 sub-strate 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.
- Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard,Trzepizur, Damian
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- Microwave michaelis-becker synthesis of diethyl phosphonates, tetraethyl diphosphonates, and their total or partial dealkylation
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Diethyl phosphonates and tetraethyl alkyldiphosphonates were efficiently and rapidly prepared via the Michaelis-Becker reaction, under microwave irradiation. These compounds were then hydrolyzed to phosphonic and diphosphonic acids or selectively monodealkylated to give monoesters of phosphonic acids and symmetrical diethyl esters of diphosphonic acids. These reactions were also achieved rapidly in satisfactory yields with microwave methodology. This methodology was applied with success to the functionalization of a polymer resin.
- Meziane, Dalila,Hardouin, Julie,Elias, Abdelhamid,Guenin, Erwann,Lecouvey, Marc
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experimental part
p. 369 - 377
(2010/07/16)
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- Synthesis and structural study of long-chain hydrocarbon alkylphosphonic acids
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Long-chain dialkyl alkylphosphonates were synthesized by radical addition of dialkyl hydrogenphosphonates onto alkenes in presence of di(t-butyl) peroxide. This synthetic route leads to high yields between 94 and 97%. We performed chemical modifications of these phosphonates in order to obtain acidic derivatives. The structure of these compounds was characterized by NMR analyses and mass spectroscopy. We also studied their thermal behaviour and various crystalline phases were put in evidence by differential scanning calorimetry and optical microscopy. The thermal stability of these compounds was compared by thermogravimetric analyses.
- Gaboyard,Hervaud,Boutevin
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p. 877 - 891
(2007/10/03)
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