Temperature and concentration dependence of the activity of quinones of presumed inhibiting action

The inhibiting properties of a series of organic compounds with a quinonoid structure have been electrochemically studied. The effect of the area and the structure of the organic molecule on the activity of the quinones has been followed. The compounds studied inhibit mild steel's corrosion in model cooling water and prove to be inhibitors of a cathodic type. The degree of corrosion inhibition is a function of the temperature, the concentration and the nature of the substance. The protective effect of the quinones is explained with their adsorption on the corroding surface. The adsorption itself is facilitated by the presence of π-electron systems and conjugated bonds in the molecules as well as by the increase of the molecule's size. Some differences in the behaviour of the p- and o-compounds studied are observed.