Phosphorus-containing podands 4. Effect of polyether chain length of oligoethylene glycol bis(ortho-diphenylphosphinylmethyl)phenyl ethers on their complex-forming and selective properties with respect to alkali metal cations

Alkylation of o-(diphenylphosphinylmethyl)phenol by oligoethylene glycol ditosylates leads to a series of acyclic polyether complexing agents (podands) with phosphinylmethylphenyl terminal groups. A conductometric method in tetrahydrofuranchloroform (41 by volume) has been used to determine the stability constants of the podands with alkali metal 2,4-dinitrophenoxides. Several of the prepared ligands exhibited a high Li/Na, Na/K, and Li/K selectivity. For lithium and sodium cations, the curve of complex-forming ability against the overall number of donor centers in the structure of the podand has a maximum for the case of tetraethylene glycol bis(o-diphenylphosphinylmethyl)phenyl ether. For lithium cations, this compound surpasses the crown ethers in terms of its effectiveness and is the most powerful of the phosphoryl-containing complexing agents. For potassium, rubidium, and cesium cations, the complex-forming ability increases with increase in the number of oxygen donor centers in the polyether chain of the ligand.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1990–1997, September, 1989.Previous communications, see [2, 3].