Synthesis of 5-benzyl-5-((5-nitropyridin-3yl)methyl)-1,3,5-dithiazinan-5-ium through one-pot reactions, characterization and study as a corrosion retardant in high salinity oil fields.

Abstract

This study included the preparation of a new heterocyclic compound namely 5-benzyl-5-((5-nitropyridin-3-yl) methyl)-1,3,5-dithiazinan-5-ium (BNPD) by a simple powerful method and an environmentally acceptable. The BNPD compound contains O, N, and S heteroatoms that have been inserted into the chemical structure by one step consisting of several transformations. The BNPD structure has been characterized using several techniques like FT-IR, 1H-NMR, 13C-NMR, and G-C mass. The prepared molecule has been studied as an inhibitor of carbon steel corrosion (N-80), which is generally used in oil fields. The BNPD effectiveness has been studied as an anti-corrosive material in saline water that accompanies the extraction of crude oil. Saline water contains dissolved solids estimated at 239581mg/l, conductivity 254.23 ms/cm, and pH 6.1. The retardant has been evaluated by electrochemical impedance spectroscopy technique (EIS), potentiodynamic polarization technique (PP), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM/EDX), and weight loss method (WL) at 308K(±1). It was noted that inhibition efficiency increases with increasing BNPD concentration. The results of potentiodynamic polarization showed that the studied inhibitor molecules act as a mixed-type inhibitor, while the results of weight loss showed that these molecules adsorbed on the carbon steel surface through physical and chemical adsorption simultaneously. The results of the SEM/EDX indicated that slight corrosion occurred at the inhibitor was added, where the EDX spectrum of N-80 at 80 mg.dm-3 of inhibitor was noticed approximately similar to the polished carbon steel spectrum. Furthermore, the electronic and physic-chemical characteristics of BNPD have been calculated like EHOMO, ELUMO, energy gap, total energy, lipophilicity coefficient, molecule surface area, molecular volume, molecular polarizability, molar refractivity, dipole moment, solvation energy, theoretical inhibition efficiency, and electrostatic potential surfaces. The BNPD compound has shown wonderful results in corrosion inhibiting, where its efficiency optimum reached 91.14%, 93.60%, and 93.46% for WL, EIS, and PP techniques, respectively. Either theoretical efficiency reached 90.25%.