Influence of the alkyl chain on the protective effects of 1,2,3-benzotriazole towards copper corrosion. Part I: inhibition of the anodic and cathodic reactions

1,2,3-Benzotriazole (BTAH) and some of its 5-alkyl-derivatives (methyl-, butyl-, hexyl-, octyl-, dodecyl-) were tested by using different electrochemical techniques in order to investigate the influence exerted by the aliphatic chain length on the inhibiting action of the base molecule towards OFHC copper corrosion in acidic sulphate and saline solutions. The polarization curves, recorded after a 3 h immersion in acidic sulphate solution, showed that: more than 1 mu mole l(-1) of the additives had to be in the solution to reduce the copper corrosion rate; the BTAH inhibiting efficiency increased with the length of the side alkyl chain up to six carbon atoms; chiefly, the action of the anodic inhibitor of the base molecule is strengthened. The hexyl derivative also exhibited a good efficacy in acidic chloride solution. (C) 1999 Elsevier Science Ltd. All rights reserved.