Determination of Inhibition Properties of Caffeine, Theophylline and Their Allylic and Propargylic Derivatives on API 5L X70 Steel Immerse in 1M HCl

The determination of the inhibitory properties of caffeine and theophylline and their allylic and propargylic derivatives as inhibitors of corrosion was developed for API 5L X70 steel immerse in 1M HCl by means of the electrochemical impedance technique. It was found that caffeine and its derivative propargylic show good inhibition efficiency 91% at 5 and 20 ppm respectively. Furthermore, it is also shown that while caffeine and propargyl-theophylline were adsorbed on the steel surface trough a chemisorption process, theophylline and allyl-theophylline follow a combined adsorption process.