2-Mercaptobenzothiazole as a Corrosion Inhibitor in Low Temperature Ionic Liquids

The corrosion of metals (copper, zinc, and plain carbon steel) in dialkylimidazolium tetrafluoroborates depends on the presence of traces of impurities in the ionic liquids. Water, chlorides, and especially simultaneous presence of the both impurities enhances the pitting corrosion of metals. The products of corrosion contain the metal of interest as well as nitrogen, boron, chlorine, fluorine, carbon, and oxygen. The rate of corrosion of metals in both pure and water- and/or chloride-containing tetrafluoroborates can be substantially reduced in the presence of 2-mercaptobenzothiazole. In 0.001 M 2-mercaptobenzothiazole the rate of corrosion drops by 70 % at 25 degrees C and by 60 % at 200 degrees C with respect to the corrosion rate in absence of corrosion inhibitor. We speculate that the other derivatives of azoles and thiazoles, which have been successful as corrosion inhibitors in aqueous media, can also be efficient in low temperature ionic liquids.