21921-96-0Relevant articles and documents
Microwave-assisted ionic liquid-catalyzed selective monoesterification of alkylphosphonic acids—an experimental and a theoretical study
ábrányi-Balogh, Péter,Drahos, László,Harsági, Nikoletta,Henyecz, Réka,Keglevich, Gy?rgy
, (2021/09/07)
It is well-known that the P-acids including phosphonic acids resist undergoing direct es-terification. However, it was found that a series of alkylphoshonic acids could be involved in mo-noesterification with C2–C4 alcohols under microwave (MW) irradiation in the presence of [bmim][BF4] as an additive. The selectivity amounted to 80–98%, while the isolated yields fell in the range of 61–79%. The method developed is a green method for P-acid esterification. DFT calculations at the M062X/6–311+G (d,p) level of theory (performed considering the solvent effect of the corresponding alcohol) explored the three-step mechanism, and justified a higher enthalpy of activation (160.6–194.1 kJ·mol–1) that may be overcome only by MW irradiation. The major role of the [bmim][BF4] additive is to increase the absorption of MW energy. The specific chemical role of the [BF4] anion of the ionic liquid in an alternative mechanism was also raised by the computations.
Synthesis of alkyl hydrogen alkylphosphonates
Pienaar, Andre,Erasmus, Cornelis M.,Wentzel, Mauritz,Cowley, Eugene H.
, p. 149 - 159 (2007/10/03)
The synthesis of alkyl hydrogen alkylphosphonates 1 was studied. Different synthetic routes were investigated and it was found that alkylphosphonic anhydrides can serve as ideal precursors for the synthesis of those half-acids. It was also shown that isopropyl phosphonic dichloride reacts in a unique fashion to produce alkyl hydrogen isopropylphosphonates in moderate yields.
