The Synthesis of Vanillin Derivatives and the Study of Its Corrosion Inhibition Activities toward Carbon Steel in 1% (w/v) NaCl Environment

• Main Author: Putri Novianti, Nadya
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/37956
• Institution: Institut Teknologi Bandung

Corrosion is an important issue for the industrial sector in Indonesia, especially sectors of the oil and gas industry. In the oil and natural gas, crude oil or gas fluid flow through carbon steel pipelines. However, carbon steel pipelines are susceptible to corrosion both on the outer surface and the inner parts of the pipes. The most efficient prevention of corrosion on the inner part of the pipe is done by injecting a chemical inhibitor, in particular a chemical inhibitor of organic compounds based which are environmentally friendly inhibitors. Vanillin is a green corrosion inhibitor, therefore its derivative compounds are expected to have the same function. In this research, the synthesis of derivatives compounds of vanillin (compound 1) were carried out. The vanilline derivatives are vanillic acid (compound 2), which was synthesized through an oxidation reaction of compounds 1; and a pyrimidone derivative, namely ethyl 4- (4-hydroxy-3-methoxyphenyl) -6-methyl-2-oxo-1,2,3,4- tetrahidropirimidon-5-carboxylate (compound 3), which was synthesized through a Biginelli condensation reaction of compound 1 with urea and ethyl acetoacetate. Based on the measurement of FTIR spectrum of compound 2, there is a vibration peak at wave number of 2951 cm-1 which corresponds to the -OH group on the carboxylic acid and at wave number of 1680 cm-1 which indicated the C=O group on the carboxylic acid. While on the analysis of FTIR spectrum of compounds 3, there is a vibration peak at wave number of 3360 cm-1 which indicated the –NH group, at 1700 cm-1 which corresponds to the C=O group in ester, and at 1649 cm-1 which shows the amide groups. Based on the measurement results of LC- MS, there is a peak in the mass spectrum of compounds 2 with the [M+H]+ at 169.131 corresponding to the molecular weight of the compound 2, which is 168.148 g/mol. While the mass spectrum of compounds 3 showed peak of [M+H]+ at 307.273 corresponding to the molecular weight of compound 3, which is 306.318 g/mol. 1H-NMR and 13C-NMR spectrums in DMSO-d6 solvent comfirmed that compounds 2 and 3 was succesfully synthesized. Based on the results of the spectroscopic data analysis, it can be concluded that the compounds 2 and 3 have been successfully synthesized from compound 1. The measurement of corrosion inhibition activities of the compounds 1, 2, and 3 was analyzed using Electrochemical Impedance Spectroscopy (EIS) and Tafel extrapolation with variations in the concentrations of 10, 25, 50, 100, and 150 ppm. From the results of the EIS measurements, it was obtained that the percentage of corrosion inhibition efficiency (% IE) of compound 1 is 44.66% at 100 ppm and temperature of 30 oC, while % IE of compound 2 is 67.39% at 100 ppm and temperature of 30 °C, and %IE of compound 3 is 23.11% at 10 ppm and temperature of 30 oC. The Tafel extrapolation measurements showed that compound 1 is a mixed inhibitor (ohmic inhibitor), while compound 2 and 3 are anodic inhibitors. Based on the analysis of the electrochemical data, the ?Gads values of compounds 1, 2 and 3 are -34.61 kJ/mol, -33.88 kJ/mol, and -40.41 kJ/mol, respectively. Based on the value of ?Gads it is known that the mechanism of corrosion inhibition of compounds 1 and 2 is via semi-physical or semi-chemical adsorption process, while compound 3 is via chemisorption process on the surface of carbon steel.