Thermal investigations of cefadroxil complexes with transition metals

The cefadroxil (Cef) complexes with transition divalent metals of the formula MCef·nH2O (where n=2 for M=Cu2+, Ni2+, Zn2+ and n=3 for Co2+) and CdCef1.5·4H2O were prepared and characterized by elemental and infrared spectra. The thermal analysis of the investigated complexes in air atmosphere was carried out by means of simultaneous TG-DSC technique. During heating in air they lose bound water molecules and then decompose to oxides: Co3O4, NiO, CuO, ZnO and CdO. The CdCef1.5·4H2O complex forms probably an intermediate product Cd2OSO4. The combined TG-FTIR technique was employed to study of decomposition pathway of the investigated complexes. The first mass loss step is the water loss of the complexes. Next, decomposition of cefadroxil ligand occurs with evolution of CO2 and NH3. At slightly higher temperature COS is observed according to decomposition of cephem ring. Additionally, as decomposition gaseous products: HCN, HNCO (HOCN), H2CNH, CO, SO2, hydrocarbons and carbonyl compounds were observed. The formation of metal sulfates is postulated as solid intermediate product of decomposition in the argon atmosphere.