Synthesis and study of corrosion inhibition of lsoxazolidines for mild steel in acid medium

Abstract EN

Several new isoxazolidines compounds having different degree of steric hindrance and hydrophobic alkyl chains are prepared efficiently using single-step nitrone cycloaddition reactions.

The resultant 1, 3- substituted isoxazolidines containing methyl, isopropyl and t-butyl groups at N (1) and alkyl groups C6H13, C10H21, C12H25, C14H29 and C16H33 at C (5) positions are characterized by NMR spectral analysis.

At lower temperature (-30 oC), the NMR spectra revealed the presence of two distinct interconverting forms of the isoxazolidines due to slow nitrogen inversion process.

These isoxazolidines are tested for corrosion inhibition of mild steel in 1 M and 5 M HCl at 50-70 °C range and in 1 N H2SO4 at 40-70 °C range by gravimetric and electrochemical methods.

Most compounds have shown excellent corrosion inhibition efficiency (IE%) in acidic solution.

Steric hindrance around the nitrogen centers and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100-400 ppm) are found to increase the inhibition efficiency of the isoxazolidines.

Experimental results agree with the Temkin adsorption isotherm.