Two derivatives of acetylacetone (acac, 1), namely 3-butyl-acac (2) and 3-allyl-acac (3), were synthesized. A liquid-liquid partition and spectrophotometric methods were used to examine the process of complexes formation of all ligands with Cu(II) ions. It has been shown that 2 and 3 were forming two very stable complexes of ML and ML2 type. The absorption spectra proved that the extraction of copper was simplified because flat-square complexes were formed. The high values of partition ratios of two types of complexes confirm this fact. The rate of extraction of Cu(II) complexes decreases in the order 3>2>1.