Partial synthesis of [1-14C]phytanic acid

[1-¹⁴C] Phytanic acid has been prepared in good yield from the unlabeled acid. Pristanyl iodide, prepared from the latter by a modified Hunsdieker reaction, is converted to the corresponding [¹⁴C]-nitrile by reaction with sodium [¹⁴C] cyanide in dimethyl sulphoxide; hydrolysis of the [¹⁴C] nitrile yields [1-¹⁴C]phytanic acid. The labeled acid should prove to be a useful substrate for the diagnosis of Refsum's disease.