Branched alkylphosphinic and disubstituted phosphinic and phosphonic acids: effective synthesis based on a-olefin dimers and applications in lanthanide extraction and separationстатья
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Аннотация:A number of mono-alkylphosphinic acids RCH2CH2CH(R)CH2P(O)(H)OH 8–12 were obtained via
interaction of a-olefin vinylidene dimers RCH2CH2C(R)]CH2 3–7 (R = n-butyl, 3, 8; isobutyl, 4, 9; n-octyl, 5, 10; isopropyl, 6, 11; cyclohexyl, 7, 12) with H3PO2 in an isopropanol medium at 90C. Hydrophosphinylation of 3 by 8 or PhPO2H2 at 140C resulted in disubstituted acids 13 and 14. Alkylmethylphosphinic acids 15–19 and functionalized alkylphosphinic acids 20–22 have been synthesized via interaction of silyl ethers of mono-alkylphosphinic acids 8–12 with MeI, (2-chloromethyl)pyridine, acrylic acid or acrylamide. Non-catalytic hydroalumination of 3 with subsequent interaction with PCl3 and oxidation with SO2Cl2 led to the phosphonic acid anhydride, which was further used to obtain alkylphosphonic acids 23 and 24. It has been found that phosphinic acids 8–12 surpass di(2-ethylhexyl)phosphoric acid (extractant P204) in non-selective Ln3+ extractability (Ln = La, Pr, Nd, Dy and Lu). Significantly higher selectivity for heavy lanthanide extraction (Ln = Dy, Lu), compared to that of P204, is achieved by using a minimal excess of disubstituted phosphinic acids 13–24. Acid 13, which contains two branched substituents, demonstrated unique selectivity in the extraction of Lu in the presence of the other lanthanides. Dialkylphosphinic acids 16–18 and alkylarylphosphinic acid 14 possess a significant potential for the Pr/Nd pair separation. Taking into account the availability of 8–24 and the structural variability of the initial a-olefin dimers 3–7, the newly obtained compounds represent a promising group of rare-earth element extractants.