The solubilities and the refractive indexes of saturated solns. of the title systems at 30癈 have been studied and the corresponding solubility diagrams and refractive index diagrams were constructed. All the solubility curves and refractive index curves of these systems consist of three branches, corresponding to 4-acetylantipyrine (ACAP), Ln(ACAP)3(ClO4)4譶H2O (Ln = La, n = 4, Sm, 2; Yb, 2) and Ln(ClO4)3譶H2O (Ln = La, n = 8; Sm, 9; Yb, 8), resp. All the three ternary compounds formed in the title systems are new compounds reported for the first time in this paper. They are incongruently soluble in water. They were characterized by chem. anal. and elemental anal., IR spectra, UV spectra, TG-DTG and X-ray powder diffraction. The complexation ability of antipyrine 4-position acyl derivatives have been discussed briefly.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, PHASE EQUILIBRIUM, INFRARED SPECTROPHOTOMETRY, ELEMENTAL ANALYSIS, X-RAY DIFFRACTION ANALYSIS, SOLUBILITY, TERNARY SYSTEM, THERMOGRAVIMETRY, REFRACTIVE INDEX