1
|
Ábrányi-Balogh P, Harsági N, Drahos L, Keglevich G. A Study on the Direct Esterification of Monoalkylphosphates and Dialkylphosphates; The Conversion of the Latter Species to Trialkylphosphates by Alkylating Esterification. Molecules 2022; 27:molecules27154674. [PMID: 35897850 PMCID: PMC9331942 DOI: 10.3390/molecules27154674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 12/04/2022] Open
Abstract
The microwave (MW)-assisted direct esterification of certain P-acids is a green method. Quantum chemical calculations revealed that the activation enthalpy (ΔH#) for the exothermic monoalkylphosphate → dialkylphosphate transformation was on the average 156.6 kJ mol−1, while ΔH# for the dialkylphosphate → trialkylphosphate conversion was somewhat higher, 171.2 kJ mol−1, and the energetics of the elemental steps of this esterification was less favorable. The direct monoesterification may be performed on MW irradiation in the presence of a suitable ionic liquid additive. However, the second step, with the less favorable energetics as a whole, could not be promoted by MWs. Hence, dialkylphosphates had to be converted to triesters by another method that was alkylation. In this way, it was also possible to synthesize triesters with different alkyl groups. Eventually a green, P-chloride free MW-promoted two-step method was elaborated for the synthesis of phosphate triesters.
Collapse
Affiliation(s)
- Péter Ábrányi-Balogh
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, 1117 Budapest, Hungary;
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary;
| | - Nikoletta Harsági
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary;
| | - László Drahos
- MS Proteomics Research Group, Research Centre for Natural Sciences, 1117 Budapest, Hungary;
| | - György Keglevich
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary;
- Correspondence: ; Tel.: +36-1-463-1111 (ext. 5883)
| |
Collapse
|