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In this chapter, the authors investigate recent advancements in the manufacture of chemical compounds containing a benzoxazepine-based heterocycle. Specifically, they synthesized the Benzoxazepine Derivatives using two organic reactions to test its efficacy as an inhibitor against the corrosion of mild steel in acidic pickling baths. The findings reveal that the corrosion inhibitor efficiency increased from 79.4% to 93.3%. This study also employed the Langmuir adsorption model to show that Benzoxazepine Derivatives studied adsorbed spontaneously on the metal surface with a mixed-type nature, forming a coating that is verified by SEM/EDS. The negative free energy of adsorption values and the significant relationship between the inhibitor molecule and the adsorption energy further support our findings. This study demonstrates the potential of benzoxazepine derivatives as effective inhibitors of mild steel corrosion in acidic pickling baths, with significant implications for the manufacturing industry. Continued research in this field is of utmost importance.

A simple and efficient one-pot synthesis of tetrahydrobenzo[b]pyrans and dihydropyrano[4,3-b]pyrans derivatives was described. These reactions were realized through a three-component condensation of aromatic aldehyde, malononitrile, and 5,5-dimethyl-1,3-cyclohexanedione or 4-hydroxy-6-methylpyran-2-one using phosphate fertilizers monoammonium phosphate, NH4(H2PO4)2, (MAP), diammonium phosphate, (NH4)2(HPO4), (DAP), and triple superphosphate, Ca(H2PO4)2.H2O, (TSP) as heterogeneous catalysts. Under optimal reaction conditions, these fertilizers show an excellent catalytic activity. Indeed, the tetrahydrobenzo[b]pyrans and dihydropyrano[4,3-b]pyrans derivatives were obtained with good yields in short reaction times. Also, these fertilizers can be reused at least four times without significant loss of their catalytic activity. Therefore, their application can be contributing to the development of green chemistry.

The synthesis of quinoxaline derivatives were heterogeneously catalyzed by phosphate-based catalyst fertilizers, MAP, DAP, or TSP. The reaction affords the desired products in excellent yields at ambient temperature. A series of studies were conducted to investigate the effect of solvent reaction, its volume, and catalyst amount. A study of the recyclability of catalysts removed from the reaction mixture by simple filtration was also carried out to find that the three phosphate-based catalysts retain their catalytic activities up to six cycles.

This work is devoted to the study of the inhibition of corrosion of mild steel (MS) in molar hydrochloric acid (1 mol⋅L-1 HCl) by two named quinoxaline derivatives namely, 2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline (HQ) and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline (CQ). The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques (stationary and transient techniques). The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates (ηEIS%) reached up to 91% and 94.2% at 10−3 mol⋅L-1 for HQ and CQ, respectively. The mentioned molecules are classified as mixed-type inhibitors. The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol⋅L-1 medium obeys the Langmuir adsorption isotherm. The results of the scanning electron microscope (SEM) showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied. Elementary analysis is obtained by energy dispersive X-ray spectroscopy (EDS). The inhibition property was further elucidated by theoretical approaches such as: Density Functional Theory (DFT), quantum chemical descriptors (QCD), local reactive indices, solvent effect, theoretical complexation, Molecular Dynamic (MD) simulation, effect of temperature on adsorption energy (Eads), Radial Distribution Function (RDF), and Mean Square Displacement (MSD). The results of these approaches support the experimental results.

Metallic materials are well known and widely used in various industrial sectors. However, they can be easily corroded in various aggressive environments. The protective action of stainless steel by two organic pyrazole compounds: {1-amino-5,10-dioxo-3-(p-tolyl)-5,10-dihydro-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile} and {1-amino-3-(2-chlorophenyl)-5,10-dioxo-5,10-dihydro-1H-pyrazolo[1,2-b] phthalazine-2-carbonitrile} in H2SO4 2.0M medium was studied using the electrochemical technics (Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization), Scanning Electron Microscopy (SEM) and Energy Dispersion X-ray spectroscopy (EDX). Polarization curves indicate that both compounds act as anodic inhibitors. A suitable equivalent electrical circuit model was used to calculate the impedance parameters. The adsorption study showed that these compounds are adsorbed to the steel surface according to the adsorption isotherm of Langmuir. Effect of temperature was also investigated and activation parameters were evaluated.

The 4H-pyranopyrazoles are an important class of heterocyclic compounds due to their pharmacological and biological properties.1 Compounds bearing the pyranopyrazole system have been found to have ...

The aim of this work is to prove the efficiency of the Phosphate fertilizers mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP) and triple-super phosphate (TSP) as a “green” heterogeneous catalysts for the synthesis of 2-aryl-2H-benzo[b][1,4]thiazin-3(4H)-ones via the C-S and C-N coupling process of gem-dicyano epoxide with α-aminothiophenol. To optimize the reaction conditions, the synthesis was conducted with a range of solvents, catalyst amounts and catalyst particle sizes. Also, the potential recyclability of the catalysts was confirmed by running the reaction using the recycled catalyst.

A new strategy has been proposed for the synthesis of 9-arylhexahydroacridine-1,8-diones by three-component condensation of aromatic aldehydes with 5,5-dimethylcyclohexane-1,3-dione and ammonium acetate in ethanol, using nontoxic, available, and inexpensive phosphate fertilizers [monoammonium phosphate (MAP), diammonium phosphate (DAP), and triple super phosphate (TSP)] as heterogeneous catalysts. Notable advantages of the proposed method include operational simplicity, low cost of the reactants, favorable environmental profile, good yield, short reaction time, recovery and reuse of the catalyst, and valorization of Moroccan natural phosphate.

The present work focused on developing a new protocol of the 1-(benzothiazolylamino) methyl-2-naphthol derivatives synthesis by condensation of three compounds, i.e. aromatic 2-naphthol, 2-aminobenzothiazole and aldehyde. Furthermore, this reaction was carried out in the presence of three heterogeneous phosphate catalysts: monoammonium phosphates (MAP), diammonium phosphate (DAP), and trisuperphosphate (TSP). Moreover, this method offered many advantages, such as: very high yields, shorter reaction times, and the catalysts, can be easily recovered and reused without any loss of their catalytic activities. Copyright ©2019 BCREC Group. All rights reserved

The present work reports a simple procedure for the preparation of cadmium pyrophosphate (Cd2P2O7) from the modification of mono-ammonium phosphate (MAP) fertilizer by cadmium chloride (CdCl2). The obtained support has been characterized by microscopic and spectroscopic methods, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and infrared spectroscopy (IR). The catalytic activity of Cd2P2O7 has been evaluated by its application for the first time as a heterogeneous catalyst in the 2,3-dihydroquinazolin-4(1H)-one derivatives synthesis. This synthesis has been realized through the condensation of anthranilamide with different aromatic aldehydes. The optimum reaction conditions have been determined by studying the effect of the catalysts amount, the solvent nature, and the temperature. The results show that Cd2P2O7 possesses a high catalytic efficiency because of the excellent yields and the short reaction times obtained for the studied reactions. Furthermore, it presents a remarkable capacity for recovery and reusability, and therefore its application contributes to the green chemistry development.

Novel film catalysts of the polystyrene (Ps) and trimethyl phosphate (P) nanoparticles were synthesized on glass substrates by soft chemistry using doctor blade method. Subsequently, the prepared Ps–P film catalysts were characterized by various techniques, including fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), density (d), polarizing microscope (PM), X-ray diffraction (XRD) and thermal analysis. According to the results, the structure and morphology of film catalysts were confirmed by all analyses. The Ps–P films, as heterogeneous solid catalysts, have demonstrated strong activity for Knoevenagel condensation, producing alkenes of high purity. The recovered yields are excellent, up to 96% in solvent-free conditions at room temperature. Further, the film catalysts have showed high stability, good reusability (up to five times) while maintaining their efficiency and productivity. In the present study, the polystyrene/phosphate film catalysts were characterized and synthesized by soft chemistry method. These film catalysts were show an excellent catalytic activity for Knoevenagel condensation reaction. Further, they have demonstrated high yields, in solvent-free at room temperature, with a good reusability and high stability.

In this work, the condensation of aromatic aldehydes with different two-substituted aniline catalyzed by NH3(CH2)5NH3BiCl5 as heterogeneous and recyclable catalyst was reported. It was demonstrated that NH3(CH2)5NH3BiCl5 can act as an efficient and active catalyst and is reusable for six runs without a significant loss of their catalytic activity. Simple preparation of the catalyst, high catalytic activity and good reusability are noteworthy advantages of this catalytic system in the synthesis of benzoxazole, benzimidazole and benzothiazole heterocycles at room temperature under solvent-free conditions.

The novelty of this work is to propose a new process consisting to the modification of triple superphosphate (TSP) by sodium nitrate (NaNO3) for the preparation of a heterogeneous catalytic support Na2Ca(HPO4)2 (calcium hydrogen disodium phosphate). This product has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). The catalytic activity of Na2Ca(HPO4)2 was examined in Knoevenagel condensation between 4-chlorobenzaldehyde and malononit rile as a model reaction. The optimization of the reaction operating conditions was carried out based on a study of the effect of various parameters, namely reaction time, the catalyst charge, the nature, and volume of solvent on the reaction yield. From these considerations, this catalyst proves its efficiency since it allows to obtain the product with excellent yields in a short reaction time. Moreover, it has been reused several times without any significant loss of its activity. The process developed herein can be considered as an ecological and economical method because the catalyst used is non-toxic, cost-effective and easy to prepare.

This article presents a simple and practical method for the synthesis of 3,4-dihydropyrano[c]chromene, which are heterocyclic compounds possessing a wide range of biological properties. They have been obtained by the condensation of an aromatic aldehyde, malononitrile and 4-hydroxycoumarin in presence of phosphate fertilizers (MAP, DAP and TSP) as heterogeneous catalyst and ethanol as an ecological solvent that makes this procedure environmentally friendly. The aim of this study is the investigation of their catalytic activities through the determination of the optimum conditions, which are the reaction time, the mass of the catalyst used, the nature of the solvent and its appropriate volume. These optimum conditions are the mean ones in the catalytic efficiency and they permit to obtain better yields with shorter reaction times. The developed method herein presents a green strategy which is characterized by mild reaction conditions, high to excellent yields, short reaction times and easy catalyst recovery. In addition, the experiment shows that these catalysts can be reused successfully several times without significant loss of their catalytic activity.

The corrosion inhibition of carbon steel in a 1.0 M HCl solution, using 4-amino-2-(4 chlorophenyl)-8-(2,3-dimethoxyphenyl)-6-oxo-2,6-dihydropyrimido [2,1b] [1,3] thiazine- 3,7-dicarbonitrile (ACMPT) was investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculations. Polarization curves indicate that the studied compound was acting as a mixed inhibitor with predominant cathodic effectiveness. The inhibition efficiency decreased with an increased temperature, and the thermodynamic and activation parameters obtained from this study were discussed. The adsorption behavior of ACMT follows Langmuir's isotherm. In addition, Density Function Theory (DFT) calculations were performed on the studied molecule. The theoretical parameters obtained from this method are in good agreement with the experimental results.

In this work, an efficient, easy, and green process has been developed for the synthesis of 2,3-dihydroquinazolin-4(1H)-one from a condensation reaction of anthranylamide with various aromatic aldehyde using of phosphate fertilizers, mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP) and triple super phosphate (TSP) as heterogeneous catalysts. The reaction conditions were optimized taking into account of some parameters which control the reaction, namely the nature and the volume of the solvent and the mass of catalyst. The results show that the catalysts used herein are very interesting because they present a good catalytic activity and they are reusable for at least five cycles without any degradation of their activity .

The present paper examines the adsorption of two novel heterocyclic compounds of the pyran derivatives, namely, 2-amino-4-(2-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (PY-2Cl) and 2-amino-4-(4-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2c]chromene-3-carbonitrile (PY-4Cl) against the corrosion of mild steel (MS) in molar hydrochloric acid (HCl) medium. The experimental investigation was carried out utilizing a series of techniques including Weight Loss (WL), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). Results showed that inhibition effectiveness of PY-2Cl and PY-4Cl increases with their concentration. Polarization results showed that PY-2Cl and PY-4Cl displayed mixed type behaviour. Inhibition efficiencies of PY-2Cl and PY-4Cl followed the order: 85.8% (PY-4Cl)

This work aims to prepare a new bimetallic phosphate catalyst using a new simple and effective method. This new catalyst was ready for the first time by a modification of Triple Super Phosphate (TSP) fertilizer with silver sulfate (AgSO4), followed by the impregnation of the aluminum atoms using aluminum nitrate (Al(NO3)3). The use of Al/Ag3PO4, for the first time as a heterogeneous catalyst in organic chemistry, offers a new, efficient, and green pathway for synthesizing 1,2-dihydro-l-phenyl-3H-naphth[1,2-e]-[1,3]oxazin-3-one derivatives by one-pot three-component cyclocondensation of b-naphthol, aryl aldehyde, and urea. The structure and the morphology of the prepared catalyst were characterized by spectroscopic methods such as X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), and dispersive X-ray spectrometry coupled with a scanning electron microscope (EDX-SEM). In addition, the optimization of the reaction parameters was carried out considering the effect of catalyst amount, the temperature, and the solvent. The procedure described herein allowed a comfortable preparation of oxazine derivatives with excellent yields, short reaction times, and in the absence of organic solvent.

Mild steel (MS) is a material frequently used in industry, but it usually suffers from extensive corrosion in the acidic environment. To reduce this processor, we used the quinoxaline molecule substituted (6-methyl-2-(p-tolyl)-1,4-dihydroquinoxaline ((CH3)2Q) with electron donor group. Corrosion inhibition potency of CH3)2Q on MS in 1 M HCl was first evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The effect of (CH3)2Q over the MS surface was analyzed by scanning electron microscope (SEM). The parameters of adsorption of the (CH3)2Q on the MS surface are determined. To better understanding of corrosion inhibition mechanisms, theoretical investigations were carried out namely the DFT, molecular dynamics simulations (MDS), radial distribution function (RDF) and mean square displacement (MSD). The outcomes of our investigation spurred us to deduce that (CH3)2Q behave as effective inhibitor for MS corrosion in 1 M HCl at all tested concentrations, the efficiency of the inhibition reaches a maximum value which equals 93.50% at 10-3 M. The type of inhibition mechanism for (CH3)2Q was mixed-type. A CPEn, Q determined by fit and graphical methods plotted by synthetic data, was utilized. The EIS findings revealed that the addition of (CH3)2Q to the corrosive medium leads to a decrease of the charge capacitance resulting in a systematic improve of the interface charge/discharge function and forms an adsorbed layer over the metal surface. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The effect of (CH3)2Q over the MS surface was analyzed by scanning electron microscope (SEM). The parameters of adsorption of the (CH3)2Q on the MS surface are determined. The results show that (CH3)2Q could offer an inhibition efficiency of 93.50 and 77.35% at 303 and 333 K, respectively. The local reactivity and distribution of the electronic density of HOMO/ LUMO shows that the molecules analyzed contain highly reactive centers distributed throughout the molecular structure. New insights were contributed by diffusion model and RDF method.

The FeCl 3 /eggshell has been a new and efficient catalyst for the rapid and simple synthesis of 2,3-dihydroquinazolin-4-ones in ethanol at room temperature. The present method has advantages of low cost, mild reaction conditions, simple workup process, better recovery and reusability of catalyst, excellent yields and environmentally friendly procedure.

A simple, efficient and green procedure has been developed for the synthesis of dihydropyrimidinones (Products of Biginelli) using phosphate fertilizers (mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP) and triple super phosphate (TSP)) as catalyst. The one-step reaction involved the three compounds, which are registered aromatic aldehydes, dicarbonyl compounds and the urea/thiourea. This new method provides some advantages such as obtaining excellent yields (98%), as well as the short duration of the reaction, which may attain 2 min. These catalytic heterogeneous systems present also the advantage of being easily recycled.

Herein, we describe a simple, highly efficient and environmentally friendly protocol for the synthesis of benzimidazoles, benzoxazoles, benzothiazoles, 3,4-dihydropyrimidin-2-ones/ thiones and quinoxalines derivatives using hybrid crystal NH3(CH2)6NH3SiF6 as a catalyst. Use of recyclable catalyst, easy work-up procedure, excellent yields, short reaction times and scalability are the important practical features of the present protocol.

Three-component reaction in one pot transformation of aldehydes, ethylacetoacetate and o-phenylenediamine was employed for the synthesis, under solvent-free, of 1,5-benzodiazepine derivatives using fertilizers mono-ammonium phosphate (MAP), di-ammonium Phosphate (DAP) and triple super phosphate (TSP) as safe, clean, and recyclable catalysts. The synthesis method seems to be operationally simple and provides access to a variety of 1,5-benzodiazepines with excellent yields in a short reaction time.

A simple, effective, green and nontoxic protocol was used for the Knoevenagel condensation and the biscoumarin derivatives synthesis. It have demonstrated that the use of a new hybrid crystal as a heterogeneous catalyst makes it possible to obtain several advantages such as: a short reaction time and exceptional catalytic activity. Furthermore, (N2H5)2SiF6 was examined for five successive cycles without significant loss of catalytic activity.

Abstrat This potential work presents a new organic molecule as a corrosion inhibitor of mild steel in HCl solution (1.0 M HCl).The organic molecule was elucidated by IR, 1H NMR and 13C NMR spectroscopy.The corrosion inhibiting effect was achieved by techniques electrochemical techniques such as Potentio-dynamic polarization (PDP) and impedance spectroscopy (EIS).The surface of the steel after corrosion tests has been identified by scanning electron spectroscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM) spectroscopy. The experimental studies were confirmed by the calculations of density functional theory (DFT) and Monte Carlo simulations (MC). The theoretical, experimental studies and analytical techniques clearly show that this molecule is a good corrosion inhibitor (91 %) of steel in HCl solution. The polarization studies show that this inhibitor acts as a mixed type inhibitor. The thermodynamic parameters show that this molecule chemically adsorbed on the surface of the steel following the isotherm of Langmuir.

Three quinoxaline-based heterocycles namely, 6-methyl-2,3-diphenylquinoxaline (Q-CH3), 6-nitro-2,3-diphenylquinoxaline (Q-NO2) and 2,3-diphenylquinoxaline (Q-H) were evaluated as inhibitor for mild steel (MS) in 1 M HCl. Inhibition effectiveness of the Q-H, Q-CH3 and Q-NO2 tested using different computational simulations and experimental methods. Results showed that inhibition effectiveness of Q-H, Q-CH3 and Q-NO2increases with their concentration. Polarization results showed that Q-H, Q-CH3 and Q-NO2displayed anodic-type behaviour. Inhibition efficiencies of Q-H, Q-CH3 and Q-NO2 followed the order: 87.6% (Q-NO2)

From a sustainable point of view, available in Morocco and cheaper, we recycled the snail shell waste (aragonite) as a potential and an eco-friendly heterogeneous catalyst for the development and the synthesis of 1-(benzothiazolylamino) methyl-2-naphthols derivatives, via one-step condensation of three reactants of the substituted aromatic aldehydes, β-naphthol with 2-aminobenzothiazole under solvent-free conditions at 85 °C. The characterization of the products (4a-g) was carried out by different analysis techniques such as: Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR and 13C NMR), high resolution mass spectrometry (HRMS) and elementary analysis. The investigations of the snail shell waste in organic reactions were showed excellent yields, very short times, ease of handling, positive aspects, great stability, reuse and environment respect, respectively.

The present work describes the corrosion inhibiting properties of three synthesized thiazole-4-carboxylates namely, methyl (E)-5-(4-chlorophenyl)-2-(((E)-4-methylbenzylidene)hydrazono)-2,3-dihydrothiazole-4-carboxylate (T1), methyl (E)-5-(4-chlorophenyl)-2-(((E)-4-nitrobenzylidene)hydrazono)-2,3-dihydrothiazole-4-carboxylate (T2) and methyl (E)-2-(((E)-4-chlorobenzylidene)hydrazono)-5-(4-chlorophenyl)-2,3-dihydrothiazole-4-carboxylate (T3) towards corrosion of mild steel (MS) in 1.0 mol/L HCl. Various techniques like electrochemical measurements, SEM-EDX analysis, Density Functional Theory (DFT) and molecular dynamics (MD) simulations were employed to probe the effects of substituent groups on inhibition performances of investigated compounds. EIS studies indicated the adsorbed protective film’s construction on the steel/electrolyte interface by tested molecules; its existence was affirmed by SEM-EDX analysis. Polarization studies revealed a mixed-type of corrosion inhibition activity. Their mode of adsorption was studied by using isotherm models, and the best match was found just in case of Langmuir adsorption isotherm. Electrochemical results showed that the polarization resistance was greatly increased, from an initial value for the MS (in 1.0 mol/L HCl) of 20.24 up to 256.7 Ω cm2 for the inhibited solution (1.0 mol/L HCl with 5 × 10−4 mol/L of T3). Tested compounds behaved as effective inhibitors for MS corrosion in HCl at all concentrations with better efficacy at an optimal concentration of 5 × 10−4 mol/L. Among all the tested inhibitors, T3 exhibited the most effective performance with an inhibition of 92 %, and the order of the inhibition potency is found within the order of T3 > T2 > T1 by all utilized techniques. The morphological examinations of the surface of MS specimens were explored by using SEM/EDX analysis. DFT calculations were not in agreement with experimental results while MD simulations confirmed the dependence of inhibition performances on the molecular structure of tested compounds.

An easy synthetic protocol for the synthesis of biologically active benzimidazole, benzothiazole and benzoxazole derivatives has been demonstrated using a hybrid crystal NH3(CH2)4NH3SiF6 as a mild and efficient heterogeneous catalyst. Short reaction times, solvent-free conditions, good to excellent yields, easy reusability and use of an eco-friendly catalyst are some of the significant attributes of the present method.

In this paper, we reported the first use of phosphate fertilizers (MAP, DAP, and TSP) as heterogeneous catalysts for organic reactions. Their catalytic activities were investigated in the first time in Knoevenagel condensation of various aromatic aldehydes with malononitrile at room temperature. These minerals phosphate showed high catalytic activities and ability to be recovering and reusing without a significant loss in their catalytic activities. In order to reach the optimal reaction conditions for Knoevenagel condensation, we carried out a kinetic study of the effect of reaction time, the effect of solvent, the amount of catalysts and the variation of the range of the particles size the more active. The best conditions were obtained by the use of these fertilizers (MAP, DAP, and TSP) in their commercial status, simply crashed in powder, without any purification, using ethanol as solvent. These phosphate fertilizers prove to be very promising and effective heterogeneous catalysts for the condensation of Knoevenagel.

Article history: Received October 21, 2015 Received in revised form December 20, 2015 Accepted 7 April 2016 Available online 7 April 2016 A simple, efficient and general method for the synthesis of 4H-pyrans is established through a multi component cyclocondensation of aromatic aldehydes, malononitrile and ethyl acetoacetate or acetyl acetone using snail shell as a natural catalyst. In this method the snail shell was used as green and reusable natural catalyst. Excellent yields, short reaction times and availability of the catalyst are the advantages of this method. © 2016 Growing Science Ltd. All rights reserved.

We have described the catalytic activities of dicalcium phosphate dihydrate (DCPD) in the condensation reaction of various substituted benzaldehydes with active methylene compound malononitrile. The influences of reaction conditions on the corresponding catalytic behavior have been investigated. The results showed that the DCPD exhibited high catalytic activity and versatility and that it can be recycled without significant loss of its activity for the condensation reactions, which shows the material is a promising new type of heterogeneous catalyst for the condensation reactions. Meanwhile, the catalytic results of DCPD compared favorably with those of other materials for Knoevenagel reactions reported previously.

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 xMCl2-yNaPO3 (MCl2 = 2,2′-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, xMCl2-yNaPO3 can be recovered by simple filtration and this catalytic system having an interesting lifetime (five cycles) with no decrease in activity., Organic chemistry; Ecological conditions; MCl2-NaPO3, Hybrid Nanocomposites, Phosphate, Heterogeneous catalytic.

A simple and efficient method for the synthesis of quinazolin-4(3H)-one derivatives via condensation of anthranilamide with aromatic aldehyde catalyzed by monoammonium phosphate (MAP), diammonium phosphate (DAP), and triple superphosphate (TSP), were developed. The modification of these three phosphate fertilizers using titanium tetrachloride (TiCl4) has increased their catalytic efficiency. The prepared titanium phosphate (TiP2O7) was characterized using microscopic and spectroscopic methods, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and infrared spectroscopy (IR). The TiP2O7 was applied for the first time as a heterogeneous catalyst in quinazolin-4(3H)-ones synthesis. High yields and short reaction times were observed in the determined optimal condition (solvent nature, volume, and catalyst amount). This study shows that the TiP2O7 presents an exciting catalytic activity and long-term durability compared to those of MAP, DAP, and TSP.

The inhibition efficiency (IE) of 4-hydroxy-8-isocyano-9-phenyl-3-(p-tolyl)-1,2-dihydropyrimido[2,1-c][1,2,4]triazepine-5,7-dione (TRC-H) and 9-(4-chlorophenyl)-4-hydroxy-8-isocyano-3-(p-tolyl)-1,2-dihydropyrimido[2,1-c][1,2,4]triazepine-5,7-dione (TRC-Cl) on the mild steel (MS) corrosion in 1 M HCl acid was studied by weight loss, electrochemical (EIS and PDP) techniques, DFT, molecular dynamic (MD) simulations, radial distribution function (RDF) and mean square displacement (MSD). TRC-H and TRC-Cl effect on the surface of MS has even been accentuated by scanning electron microscopy (SEM) and UV–visible. The adsorption on the steel is made according to the Langmuir model. Molecular dynamics simulation (MD) and Density Functional calculations were done to discussing their agreement with previously experimented results.

A simple, efficient and green procedure for synthesis 1-(benzothiazolylamino)methyl-2-naphthol derivatives via one-pot three-component condensation of aromatic aldehydes, β-naphthol and 2-aminobenzothiazole has been studied by using a novel hybrid catalyst NH3(CH2)5NH3BiCl5 under solvent-free conditions at 100 °C. This method has several advantages such as operational simplicity, recyclability of catalyst, easy workup, short reaction time and excellent yields.

Molecular dynamic, Monte-Carlo simulation approach and electrochemical methods were used to study the temperature effects on mild steel (MS) corrosion in 1.0 M of HCl in the absence and presence of triazepine carboxylate compounds. The inhibition action of all triazepine carboxylates compound studied was performed via adsorption on MS surface. Comparison between several adsorption isotherms reveals that the adsorption was spontaneous and followed Langmuir isotherm in HCl for all inhibitors and at all studied temperatures. Furthermore, selection is founded on the correlation coefficient is known nearly linear and value close to one. Kinetic and thermodynamic parameters for all inhibitors led to suggest the occurrence of chemical mechanism and also the spontaneity of the adsorption process on mild steel surface. The corrosion inhibition mechanism was discussed with the light of some triazepine carboxylate compounds constituents. The effect of molecular structure on the inhibition efficiency has been explored by quantum chemical computations and obvious correlations were observed. The binding energies of tested triazepine carboxylate compounds on Fe (110) surfaces were calculated using molecular dynamics simulation. Very good agreement was obtained with the experimental data. In addition, Atomic force microscopy (AFM) indicated that Cl–Me–CN molecules contributed to a protective layer formation by their adsorption on the steel surface. AFM parameters, such as root mean square roughness (Rq), average roughness (Ra), and ten-point height (Sz), revealed that a smoother surface of inhibited mild steel was obtained, compared to uninhibited steel surface.

The adsorption and corrosion inhibition properties of three triazepines carboxylate substituted compounds, namely, ethyl 4,9-bis(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (2Cl–Et), methyl 4,9-bis(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (2Cl–Me), and ethyl 9-(4-chlorophenyl)-8-cyano-3-hydroxy-2,7-dioxo-4-(p-tolyl)-1,2,5,7-tetrahydropyrido[1,2-b]triazepine-10-carboxylate (Cl–Me–Et) on mild steel corrosion in 1.0 M of hydrochloride acid were investigated by using weight loss, electrochemical, and theoretical investigations. It is found that these compounds act as excellent inhibitors and their inhibition efficiencies follow the order: 2Cl–Me > 2Cl–Et > Cl–Me–Et, and they depend on the type of the substituent. In addition, the possible relations between the experimental and theoretical parameters were discussed. It is found that the theoretical parameters confirmed those obtained by experimental studies. Surface roughness morphology for mild steel before and after hydrochloric acid attack is investigated and discussed using 3D-profilometry images. The scanning electron microscope (SEM) images of the corrosion product confirmed the protection offered by triazepines carboxylate derivatives on the surface of the metal immersed in both media. © 2018, Springer International Publishing AG, part of Springer Nature.

Dicalcium phosphate dihydrate (DCPD) was used as a green and reusable catalyst in order to synthesized two important categories of heterocycles, 3,4-dihydropyrimidin-2-ones and 3,4-dihydropyrimidin-2-thiones. The advantages of our method are as follow: short reaction times, green process, reduced environmental hazards and high isolated yield of products.