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In the pickling industry, corrosion can deteriorate the quality of equipment and supplies, causing financial losses and safety threats. Therefore, it has become crucial to develop novel corrosion inhibitors that are bioactive, efficient, affordable, medium-acid soluble, and ecologically safe to protect mild steel during industrial cleaning. In this work, three newly synthesized imidazo[1,2-a]pyridine derivatives were characterized by various spectroscopic techniques. The studied compounds were evaluated as corrosion inhibitors for mild steel in 1 M HCl medium using weight-loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The imidazopyridine derivatives showed excellent anticorrosion performance, their inhibitory efficiencies increased with the increase of inhibitors concentration and evolved in the following order: Imd2 (98.1%) >Imd1 (96.5%) >Imd3 (95.3%). This order was justified by the presence of two chlorine atoms in the ortho position of the Imd2 structure. The three Imd derivatives obeyed to the Langmuir isotherm, this explained the formation of an organic monolayer on the steel surface indicated by the scanning electron microscope (SEM) and the atomic force microscope (AFM). In addition, density functional theory (DFT) and molecular dynamics (MD) simulations were performed to reveal the anticorrosion mechanism. The present study illustrates at the microscopic level how mild steel resists corrosion and ensures the safety of pickling.

In this work, we report a study on the synthesis and characterization, using several spectroscopic techniques such as IR, 13C NMR, 1H NMR and mass spectroscopy, of a new series of Schiff bases based on imidazo(1,2a)pyridine (IMP) scaffold, and the evaluation of their ability to inhibit the corrosion of mild steel in 1M HCl by mass loss techniques, Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and quantum chemistry calculation based on density functional theory (DFT). The obtained results show that these inhibitors, namely (E)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)-1-(1H-pyrrol-2-yl)methanimine (IMP1), (E)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)-1-(thiophen-2-yl)methanimine (IMP2) and (E)-1-(5-nitrothiophen-2-yl)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)methanimine (IMP3), act only by reducing the cathode area without changing the mechanism of the cathodic reaction, and that the effectiveness of the inhibition increases with increasing concentration of the inhibitors. The adsorption of the studied compounds on the surface of mild steel follows the Langmuir isotherm model. And finally, we highlighted the existence of a correlation between the molecular structure of the tested inhibitors and their anticorrosion activity.

In this modest work, a local biopolymer (CHA), biodegradable, non-toxic, and soluble in acidic media, was extracted from the plant Artemisia herba-alba located in the eastern region of Morocco, and characterized by FT-IR, in order to valorize it as a corrosion inhibitor of mild steel in 1 M HCl medium. The electrochemical tests show that the extract is an excellent corrosion protective agent, reaching a maximum value of 96.17% at the concentration of 800 mg/L in the inhibitor. The potentiodynamic polarization (PDP) curves indicate the mixed behavior of the extract, to reduce the current density from 3.445 mA/cm2 to 0.104 mA/cm2 in the presence of 800 mg/L in the inhibitor. The biopolymer CHA of the extract of Artemisia herba-alba undergoes the Langmuir adsorption isotherm, whose adsorption energy is −20.75 kJ/mol, which is attributed to the presence of electrostatic and covalent bonds. In addition, the visualization of the metal surface by a scanning electron microscope (SEM) indicates the formation of a protective layer formed by the extracts of Artemisia herba-alba, which confirms the protective characteristic of the extract used. Theoretical investigations by DFT, MD, and MC confirm previous experimental results.

The purpose of this study is to demonstrate the synthesis of pyrazole-based ligands and to evaluate their catalytic properties in the oxidation reaction of catechol to o-quinone. The ligands were prepared via the condensation of (3,5-dimethyl-1H pyrazol-1-yl)methanol A with the appropriate primary amine. Four pyrazole-based ligands were successfully synthesized and characterized. These ligands provide one pyrazole sp2-nitrogen, one pyridine sp2-nitrogen, and one amine sp3-nitrogen, which were capable of coordinating to the metal. For evaluating the catalytic activity, the experiments were tested by varying the type of solvent, metal ion, anion in the metal salt, and ratios of ligands and metal salts. Excellent catalytic activities for the oxidation of catechol to o-quinone were obtained. The copper (II)-based complexes showed better reactions rates than those based on other metals (e.g., nickel, tin, and barium), which was due to the fact that the active catalytic site of the catecholase enzyme has two active sites from the existence of copper (II) ions. The composition ratios of ligands and metal salts as well as the type of anion in the metal salt bring impacts to the formation of complexes. We found also that the type of solvent contributes to the interaction and dilution of reactants in the solvent. This study demonstrated that the present ligands can be used as a model for further developments in catalytic processes relating to catecholase activity.

In order to mimic the function of catecholase activity, in situ copper (II) complexes of five ligands containing benzene and naphthalene moieties ponded by dazenyl groups: (E)-1-((2-methoxyphenyl)diazenyl)naphthalen-2-ol L1, (E)-1-((3-methoxyphenyl)diazenyl)naphthalen-2-ol L2, (E)-1- ((4-methoxyphenyl)diazenyl)naphthalen-2-ol L3, (E)-1-((2,4,6-tribromophenyl)diazenyl)naphthalen-2-ol L4, and (E)-1-((3-nitrophenyl)diazenyl)naphthalen-2-ol L5 were reported and examined, in combination with different copper salts, for their catecholase activities at ambient conditions. All complexes of tested ligands catalyze the studied reaction with the rate ranging from higher 25.1 µmol L−1 min−1 for the combination of two equivalents of ligand and one equivalent of metal in methanol, to weaker rate of 0.51 µmol L−1 min−1 for the combination of one equivalent of ligand and two equivalent of metal salt in methanol.

The reaction of the didenate N, O donor ligand 1-hydroxymethyl-3,5-dimethylpyrazole (Hdpz) with Ba(NO3)2 and HgSO4 in a molar ratio 1: 1 (M: L) leads to interesting complexes [BaNO3(Hdpz)].2H2O and HgSO4(Hdpz) with good yields. Hdpz, [BaNO3(Hdpz)].2H2O and HgSO4(Hdpz) were synthesized and characterized using different physicochemical methods such as FTIR, 1H NMR, 13C NMR and MS. The DFT theoretical studies have been carried out to calculate certain parameters of reactivity such as the molecular electrostatic potential analysis (MESP) and the calculation of maxima and minima points of MESP.

Since long times, human has been treated with plants. In nature, there are various species used for different purposes such as therapeutic, food, cosmic, dietary, chemical, pharmaceutical, agri-food, and industrial. Currently, worldwide population uses traditional medicines to meet primary healthcare needs and reduce the use of chemical drugs. Our ecosystem is a very original natural setting offering a complete range of climates favoring a rich and varied medicinal flora. In recent decades, sector of medicinal plants became very popular and focus on traditional medicine, pharmaceutical industry, food industry, manufacture of natural perfume, soap, esthetics products, insecticides, and disinfectants, etc. This chapter presents a bibliographic overview on the biodiversity of medicinal plants and theirs chemicals compounds.

Carbonylated electrophiles react with furan, thiophene, or pyrrole derivatives in the presence of catalytic amounts of bismuth triflate or chloride, leading to either electrophilic substitution or ene reaction products.

When di-n-decylphosphonate 1a or di-benzylphosphite 1b are reacted with furan imine 2a or thiophenic imine 2b , the reaction leads to an f -aminophosphonate: 3a , 3b , or 3c following an ion- or radical-based reaction.

BiCl 3 and Bi (OTf) 3 catalyze the opening of epoxides ( 1-7 ) by amines ( 8-12 ). High regioselectivities are observed. BiCl 3 et Bi (OTf) 3 catalysent la reaction d'ouverture des epoxydes ( 1-7 ) par les amines ( 8-12 ). La reaction est fortement regioselective.

Bismuth(III) salts as catalysts in the ether cleavage reaction. Bi (OTf)3 and BiCl3 react in catalytic quantity to cleaved the tertiobutyl–oxygen bound of the ethers 1, 3, 5.

The syntheses of organometallics such as alkyllithium compounds are performed. Furan and thiophene derivatives were prepared. Parameters which influence the yield have been optimized. The more important were the physical states of lithium and its sodium content and the nature of the substrate.

Diels–Alder reaction under microwave irradiation with graphite as support. ‘Dry’ Diels–Alder reactions with microwaves and reactants supported on graphite were dramatically accelerated. Although the reactions were carried out in an open reactor, a control of the evaporation of volatile reagents was possible, probably due to their confinement by graphite. © 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS microwaves / graphite / Diels–Alder

La reaction des epoxydes 1–4 avec les nucleophiles a–f ne donne pas uniquement des aminoalcools silicies mais aussi des azidoalcools avec TMSN3 et une chlorohydrine avec TMSCI. La reaction d'ouventure n'est possible qu'en presence d'acides de Lewis. Nous avons utilise en quantite catalytique Bi(OTf)3 et BiCl3. The epoxydes 1–4 reaction with the a–f nucleophiles does not give only silicate aminoalcohols but also azidoalcohols with TMSN3 and chlorohydrin with TMSCI. The opening reaction will only be possible in the presence of Lewis acids. We have used a catalytic amount of Bi(OTf)3 and BiCI3.

We have studied the Diels–Alder reaction from the dienes (1–3) and dienophiles (4–6), catalyzed by bismuth triflate and bismuth chloride. We compared these two catalysts with SnCl4, ZnI2, AlCl3 and Cu(BF4)2 respectively. With bismuth derivatives we noted no polymerisation, a better yield and a good selectivity in cycloadditions.