Alkyl-benzotriazole derivatives as inhibitors of iron and copper corrosion

5-Alkyl derivatives of benzotriazole (1–12 carbon atom long alkyl chain) were tested as inhibitors of pure iron corrosion in sulphuric or hydrochloric acid at 25°C and pure copper corrosion in acidic sulphate and saline solutions at 30°C. This series of compounds was more efficient in contrasting copper than iron corrosion and, generally, the longer the alkyl chain the higher the inhibiting performances and the longer the persistency of the inhibiting action. However, due to a decrease in the solubility, the maximum inhibiting effects were produced by the hexyl derivative. In the case of iron, these compounds were more efficient in the hydrochloric acid solution than in the sulphuric one, while for copper they were more effective in the acidic sulphate solution than in the acidic chloride solution. The higher inhibiting effects for copper can be justified by the mode of BTA adsorption, that consists in chemisorption, instead of physisorption occurring on iron.