Preparation of the Modified Platinum Electrodes Bearing the Alkali Metal Ion-Crown Ether Complexes as Mediatory Centers and Their Application to the Electroreduction of Methyl Decanoate

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The modified platinum electrodes having complexes of sodium with crown ether type ligands were prepared and utilized in the electroreduction of methyl decanoate (1) in the presence of t-BuOH as a proton donor and Bu₄NClO₄ as a supporting electrolyte. The product yield by using the modified platinum electrode having the complex of lithium or sodium ion with the monomeric ligand LA (MPt(A)–Na) was 46%. The use of the modified platinum electrodes having the complex of sodium ion with the polymeric ligands LB (MPt(B)–Na) or LC (MPt(C)–Na) gave the reduced product in 52% or 47% yield respectively. Durability of the electrodes, MPt(A)–Na and MPt(B)–Na, under the electroreduction conditions was not so high, however, the activity of the electrodes was found to be recovered by the re-complexation of sodium ion with the ligand on the surface of the used modified electrodes. The durability of the electrode MPt(C)–Na was satisfactory to use repeatedly, and the use of MPt(C)–Na as a cathode and NaClO₄ instead of Bu₄NClO₄ as a supporting electrolyte gave the reduced product in 69% yield. Moreover, using the modified electrodes in the presence of anodically dissolved magnesium ion the reduced product was obtained in >90% yield.