Abstract: Mannich（DMBM）base corrosion inhibitor,diethyl amino methyl benzotriazole was synthesized using formaldehyde（40% mass fraction）benzotriazole and diethylamine as raw materials. The optimal synthesis reaction conditions were: n(formaldehyde):n(diethylamine): n(benzotriazole) was 3:2:3, the reaction temperature was 25 ℃, and the reaction time was 0.5 h. The structures of the synthesized product were characterized by IR and NMR. The corrosion inhibition effect on carbon steel in 10% hydrochloric acid solution was investigated by weight loss method. The results showed that the synthesized DMBM had a good corrosion inhibition in an acidic medium duo to the adsorption of the benzotriazole ring in the molecule and the N atom with lone pair electrons on the amine group to the metal surface. By adding 2% DMBM into 10% hydrochloric acid solution, the corrosion rate of carbon steel at 50 ℃ was measured as 0.94mm /a, and the corrosion inhibition rate was 93%. The polarization curve test showed that DMBM is a mixed inhibitor mainly for inhibiting anodic corrosion reaction.

Key words: benzotriazole, Mannich base, corrosion inhibitor, polarization curve