The rare earth element 2-naphthoates were prepared as crystalline solids sparingly soluble in water (10−5−10−6 mol·dm−3), with general formula Ln(C10H7COO)3·nH2O, wheren=3 for La−Gd,n=2 for Tb and Dy, andn=0 for Y and Ho−Lu. During heating, the di- and trihydrated rare earth 2-naphthoates lose the crystallization water molecules
and the anhydrous complexes then decompose directly to Ln2O3, CeO2, Pr6O11 or Tb4O7. Formation of an intermediate is observed only in the case of the anhydrous lanthanum complex, which decomposes to La2O3 via La2O2CO3. The anhydrous complexes of Ho−Lu decompose directly to Ln2O3 in one step when heated. The anhydrous rare earth 2-naphthoates are very stable (up to 578–683 K).