Corrosion inhibition of steel in 1M HCl by synthesized (3-(3, 4-dimethoxyphenyl)isoxazole-5-yl)methanol in presence salt

Corrosion of metals is a major industrial problem that has attracted a lot of investigators in recent years [1]. The importance of inhibitive protection in acidic solutions is increased by the fact that steel which are more susceptible to be attacked in aggressive media, are the commonly exposed mortals in industrial environments [2]. The study of corrosion processes and their inhibition by organic compounds is a very active filed of research [3]. The aim of this work is to study the inhibiting effect of newly synthesized (3-(3, 4-dimethoxyphenyl)isoxazole-5-yl)methanol on steel in 1M HCl. For this work, first we synthesized the above compound. 3, 4-Dimethoxybenzaldehyde (1) was transformed to 3, 4-dimethoxybenzaldoxime (2) by using NH2OH in pyridine. The in situ generated nitriloxide from reaction between (2) and NaOCl, was reacted with propargylalcohol to produce (3-(3, 4-dimethoxyphenyl)isoxazole-5-yl)methanol (3) in a cycloaddition procedure. The molecular structure of this compound is shown below. Then, we studied the inhibition of corrosion of steel in 1M HCl by (3-(3, 4-dimethoxyphenyl)isoxazole-5-yl)methanol by weight loss, the effect of salt, electrochemical polarization and impedance spectroscopy (EIS) methods. The polarization curves indicate that, this compound act as mixed –type inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration to reach 86 and 94% at 5×10-4.M for isoxazole derivative in presence of salt.The adsorption of inhibitors on the steel surface is found to obey the frumkin adsorption isotherm model. EIS measurements show that the increase of the transfer resistance with the inhibitor concentration. The rate of corrosion of steel in 1M HCl without the isoxazole derivative increases with the increase of the temperature range from 298 to 3530K, but with the isoxazole compounds, the rate of corrosion of steel decrease.