Study of Aromatic Amine Inhibitors by Nuclear Magnetic Resonance

Abstract

Abstract Every and Riggs1,2 have reported the inhibitive properties of aniline and several of its derivatives. They found that the relative inhibitor effectiveness of these compounds was determined by the nature of the substituent group and its position in the aromatic ring. Some of the substituted anilines gave better than 95 percent protection to 1020 mild steel in 10 percent hydrochloric acid; a few of the substituted anilines accelerated the corrosion rate by as much as a factor of two. Differences in molecular area of these compounds were small. The observed corrosion rate could not be attributed to differences in surface area of the metal covered per molecule. No significant relationship was noted between the inhibitive properties and solubility, molecular weight or dipole moment. High resolution nuclear magnetic resonance spectra have been obtained for a group of these amine bases in cyclohexane solution. It was found that there is a linear correlation between the proton resonance frequency of the amine hydrogens and the observed inhibitor characteristics of these compounds.