RESUMO
Thermal and microwave reactions between [PcSn(IV)Cl2] (1) and the potassium salts of eight fatty acids (2 a-h) led to cis-[(RCO2)2Sn(IV)Pc] compounds (3 a-h) in yields ranging from 54 to 90 %. Compounds 3 a-h were fully characterized by elemental analysis, spectroscopy (IR, UV/Vis, multinuclear NMR), and seven X-ray diffraction structures, whereby two different allotropes were observed in two cases. The two carboxylates in 3 have a cis anisobidentate binding mode, octacoordination of the tin atoms with square-antiprismatic geometry, and pi-electron-rich nanocap shapes. On account of the latter characteristics, 3 a-h compounds have anticorrosion properties. LPR and Tafel electrochemical methods were used to characterize the behavior of these derivatives in naturally aerated sour brine, which is a common environment in petroleum production and refinery operations. The measurement of the corrosion rate of carbon steel AISI 1018 in the presence of 3 a-h (500 ppm) gave efficiencies of 61-87 % for the inhibitor performance. Of the different derivatives examined, compounds 3 e and 3 h were the most effective corrosion inhibitor prototypes.
RESUMO
Two PcSn(IV) dicarboxylate molecules were obtained through efficient microwave methodology with the aim to test them as corrosion inhibitors in the oil industry. The compounds were characterized by elemental analysis, IR, UV-vis, (1)H, (13)C NMR, and X-ray diffraction. The relative configuration of the two carboxylates is cis, placing the fatty acid moieties on the same face of the phthalocyanine macrocycle. In the solid-state the tin atoms possess square antiprismatic octacoordinated geometries. Both tin phthalocyanines were tested as corrosion inhibitors for hydrogen sulfide corrosive media showing a chemisorption process of the nanocap motifs on the metallic surface. Apparently, the length of the hydrophobic chain contributes significantly to the inhibition efficiency, in the sense that shorter chains increase the efficiency.
