Effect of benzyl substitution at different sites on the inhibition performance of pyrimidine derivatives for mild steel in highly acidic solution

Three pyrimidine derivatives, 6-amino-2-(benzylthio)-4(3H)-pyrimidinone (BTP-1), 6-amino-3-benzyl-2-(benzylthio)-4(3H)-pyrimidinone (BTP-2) and 6-(benzyloxy)-2-(benzylthio)-4-pyrimidinamine (BTP-3), were synthesized as corrosion inhibitors for mild steel in 3 M HCl solution. The inhibition performance of these three pyrimidine derivatives was studied by weight loss and electrochemical measurements, surface characterization, and theoretical calculations. It is found that these three pyrimidine derivatives act as mixed-type inhibitors with predominant cathodic effectiveness, and exhibit good inhibition performance with the order of BTP-1 < BTP-2 < BTP-3. Their adsorption behavior follows the Langmuir adsorption model. Based on the experimental results and theoretical calculations, the effect of benzyl substituent at different sites on the inhibition performance of pyrimidine derivatives is discussed. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.