Synthesis, characterization, and evaluation of some acyclic S-nucleosides of pyrazolo[3,4-d]pyrimidine-thiones as corrosion inhibitors for carbon steel in hydrochloric acid

Abstract

3-Methyl-1-phenyl-1,5-dihydro-pyrazolo[3,4-d]pyrimidine-4-thione was prepared and used as a key compound for the preparation of some S-acyclic nucleosides of pyrazolo[3,4-d]pyrimidine-thiones. Furthermore, the corrosion inhibitions of the prepared compounds towards carbon steel corrosion by 1.0 M hydrochloric acid were evaluated by chemical and electrochemical methods. The effect of inhibitors concentrations and temperatures were studied. The corrosion inhibition efficiency increased with concentrations and decreased with temperature. Addition of inhibitor molecules to the aggressive medium produces a negative shift in the open circuit potential. Galvanostatic polarization measurements reveal that thione compounds act as mixed type inhibitors. Thermodynamic activation parameters were calculated and discussed. The results were in good agreement to each other.