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In this work, we have developed a simple and very effective experimental strategy for the reaction of Knoevenagel via the condensation of aromatic aldehydes substituted with active methylene compounds in the presence of hybrid nanocomposites xMCl 2-yNaPO 3 (MCl 2 ¼ 2,2 0-dibenzimidazolyl butane dichlorhydrates), under ecological conditions. The Phosphate-Benzimidazole hybrid nanocomposite as heterogeneous catalysts has demonstrated a high catalytic activity for the Knoevenagel condensation in ethanol as an ecological solvent. It has several advantages such as light reaction conditions, a simple and ecological working procedure. Meanwhile, xMCl 2-yNaPO 3 can be recovered by simple filtration and this catalytic system having an interesting lifetime (five cycles) with no decrease in activity.

In this work, novel organic-inorganic hybrid nanocomposites M + /PO 3 − (M = 2,2′-dibenzimidazolyl butane) were prepared by soft chemistry method. The synthesis was done by ion exchange method between sodium metaphosphate anions (yNaPO 3 ) and 2,2′-dibenzimidazolyl butane dichlorhydrates cations (xMCl 2 ) in aqueous media. The MCl 2 organic salt and the M + /PO 3 − hybrid nanocomposites were characterized by using spectroscopic and microscopic analyses. The FTIR and Raman spectroscopy are showed new bands in the hybrid nanocomposites structure, which proved the interactions between PO 3 and NH of MCl 2 molecules. The UV-Vis results of MCl 2 and M + /PO 3 − materials showed a broad absorption band in 200-300 nm regions, originating from phosphate and benzimidazole molecules. The X-ray diffraction was showed the appearance of new peaks attributed to the phosphate (PO 3 ) and a reduction of the intensity of the benzimidazole peaks. The TEM images are showed changes in appearance and size of hybrid materials. Moreover, the surface of hybrids became less dark and the size of M + /PO 3 − nanocomposites diameter was < 50 nm. The EDX analysis results revealed the presence of carbon, oxygen, and phosphate, confirming the interactions between phosphate and MCl 2 organic salt.

This work aims at synthesis and characterization of 2,2[Formula: see text]-dibenzimidazolyl butane as an effective corrosion inhibitor of mild steel in sulfuric acid solution. A simple and efficient method for its synthesis in described. The chemical structure and surface morphology of 2,2[Formula: see text]-dibenzimidazolyl butane were characterized by mass spectrometry (MS), Fourier transform infrared (FTIR), Raman, 1H, [Formula: see text]C NMR spectroscopy and transmission electron microscopy (TEM). Its thermal decomposition and its variation in mass was studied by thermogravimetric analysis (TGA) coupled with differential thermal analysis (DTA). The molecular mass of 2,2[Formula: see text]-dibenzimidazolyl butane was determined to be at 290[Formula: see text]g/mol and its degradation was achieved at 455∘C. Then, the corrosion inhibition efficiency of 2,2[Formula: see text]-dibenzimidazolyl butane was studied with various concentrations in 0.5 M H2SO4 solution for mild steel by the potentiodynamic polarization and the electrochemical measurements. According to the results of electrochemical impedance spectroscopy, the inhibition efficiency decreased with concentration and reached its maximum (95.5%) at 100[Formula: see text]ppm. The polarization measurements showed that the prepared inhibitor acts as a cathodic type inhibitor. The mass loss tests are in accordance with the results of electrochemical measurements.

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