Synthesis And Corrosion Inhibition Performance Of Nitrogen-containing Organic Corrosion Inhibitors

Copper and its alloys play a very important role in diverse fields of industry because of their excellent mechanical properties and thermal conductivity. The protection of copper or its alloys is thus of particular interest. One of the most practical methods in the corrosion protection of copper and its alloys against corrosion is the use of organic inhibitors. A variety of organic compounds with functional groups containing heteroatom such as N, O, P, S, which can donate electron pairs, were found to be more useful as corrosion inhibitors in various media. The corrosion inhibitors which have N-containing are studied most in recent years.In this paper, two types of inhibitors which have N-containing have been synthesized, including a series of benzotriazole derivatives and schiff bases of 3-amino-1,2,4-triazole derivatives. These compounds have been characterized by FT-IR,1HNMR. Their corrosion inhibition for copper in media was studied by weight loss method, potentiodynamic polarization curves and quantum chemical calculation. We made some conclusions through experiment:(1) Four kinds of benzotriazole dimers linked via-CO(CH2)nCO-chain were synthesized and we obtained a new single crystal. Their corrosion inhibition effects for copper were evaluated by weight loss method and polarization curves. Benzotriazole derivatives had good performance on copper in 3.5% NaCl solution. The results of experiments revealed that the efficiency of these compounds have increased with the increase of concentration and these inhibitors all behave better compared with BTA. The inhibition efficiency decreased with increasing-CO(CH2)nCO-chain. Potentiodynamic polarization studies showed that these compounds inhibited mainly anode corrosion reactions and they were anodic type inhibitors.(2) Three kinds of Schiff bases of 3-amino-1,2,4-triazole derivatives with different groups were synthesized. Their corrosion inhibition effects for copper were evaluated by weight loss method and polarization curves. Schiff bases of 3-amino-1,2,4-triazole derivatives had good performance on copper in 5%NaHCO3 solution. The results of experiments revealed that the efficiency of these compounds have increased with the increase of concentration and the ability to giving electron of different groups. Potentiodynamic polarization studies showed that these compounds inhibited both anodic and cathodic corrosion reactions and they were mixed type inhibitors. (3) The molecular structures of these compounds were optimized by the method of B3LYP/6-31G method of Density Function Theory (DFT), and the quantum chemical parameters of these compounds were obtained. The relationship between corrosion inhibition efficiency of these compounds and their quantum chemical Parameters was also studied.