ZrOCl2 + 3Na2C2O4 + H2C2O4 → Na4[Zr(C2O4)4] + 2NaCl + H2O
Zirconium(IV) oxide-dichloride react with sodium oxalate and oxalic acid to produce sodium tetraoxalatozirconate(IV), sodium chloride and water. Sodium oxalate and oxalic acid - concentrated solutions.