Catégorie A

Mammeri S, Chafai N, Harkat H, Rachida K, Chafaa S. Protection of Steel Against Corrosion in Acid Medium Using Dihydropyrimidinone Derivatives: Experimental and DFT Study. Iranian Journal of Science and Technology, Transactions A: Science [Internet]. 2021;45. Publisher's VersionAbstract

Two dihydropyrimidinone derivatives (DHPM) were synthesized via the multi-component reaction, the yield of the synthesis reached 90%, and their structures were proved by IR, 1H and 13C NMR spectroscopy. The identified molecules were used for studying the corrosion inhibition of XC48 carbon steel in 0.5 mol L−1 H2SO4 solution. The inhibitory potentials of these compounds were determined by electrochemical methods exploiting the potentiodynamic polarization curves (Tafel method) and electrochemical impedance spectroscopy. Surface phenomena have been illustrated by atomic force microscopy. The results obtained show that the synthesized molecules are effective inhibitors, whose efficiency corrosion inhibition depends on the architecture of their structure, and it is proportional to the concentrations; it exceeds 94% for one of these inhibitors. The adsorption of these compounds on the metal surface approached the Langmuir’s adsorption isotherm. Furthermore, the electronic properties obtained using density function theory are in a good consensus with the experimental efficiencies of inhibition. The molecular dynamics simulations have allowed also simulating the interactions between the inhibitors and the metallic surface.

Bouzghaia B, Ben Moussa M, Goudjil R, Harkat H, Pale P. Chemical composition, in vitro antioxidant and antibacterial activities of Centaurea resupinata subsp. dufourii (dostál) greuter. Natural Product Research [Internet]. 2021;35 (22) :1-5. Publisher's VersionAbstract

The current study focuses on the chemical composition, and evaluation of antioxidant and antibacterial activity of the aerial parts of Centaurea resupinata subsp. dufourii. Using different chromatographic methods nine compounds 1–9 were isolated. The structural identification of isolated compounds was achieved using several spectroscopic methods NMR techniques (1H NMR, 13C NMR, COSY, HSQC, HMBC) and mass spectroscopy (ESI-MS) and by comparison with literature data. The structures of these compounds were identified as nicotiflorin (1), apigetrin (2), chrysoeriol (3), apigenin (4), chrysin (5), daucosterol (6), β-sitosterol (7), taraxastrerol (8) and lupeol (9). The antibacterial and antioxidant activities of ethyl acetate and n-butanol extracts have been evaluated. The antioxidant activity was assessed in vitro using DPPH radical scavenging method, which showed that ethyl acetate extract possessed an interesting antioxidant potential (IC50 = 36.263 ± 0.005 μg/mL).

 

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Ouache R, Harkat H, Pale P, Oulmi K. Phytochemical compounds and anti-corrosion activity of Veronica rosea. Natural Product Research [Internet]. 2019;33 :1-5. Publisher's VersionAbstract

The aim of this work is the phytochemical study of the butanolic extract of the aerial parts of Veronica rosea. Four compounds 14 have been isolated using different chromatographic methods. The structures of these compounds were determined by NMR spectral analysis and mass spectroscopy. The adsorption and anticorrosion effects of this extract were investigated towards the corrosion of copper in 1 M HNO3 aqueous by the weight loss technique and potentiodynamic polarization. The results showed that the butanolic extract is a good inhibitor and the inhibition efficiency increases with increasing of concentration of the inhibitor. The adsorption of this extract on the copper specimen surface was spontaneous and obeyed the Langmuir’s adsorption isotherm. Large value of adsorption equilibrium Constant (K ads = 35 L g−1) was obtained. The polarization experiments confirmed the data obtained by gravimetric weight-loss. Tafel plot of polarization curves indicates that the extract acts as a mixed type inhibitor.

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Ouache R, Harkat H, Pale P, Oulmi K. Phytochemical compounds and anti-corrosion activity of Veronica rosea. Natural Product Research. 2019;33 (9) :1374-1378.Abstract

The aim of this work is the phytochemical study of the butanolic extract of the aerial parts of Veronica rosea. Four compounds 14 have been isolated using different chromatographic methods. The structures of these compounds were determined by NMR spectral analysis and mass spectroscopy. The adsorption and anticorrosion effects of this extract were investigated towards the corrosion of copper in 1 M HNO3 aqueous by the weight loss technique and potentiodynamic polarization. The results showed that the butanolic extract is a good inhibitor and the inhibition efficiency increases with increasing of concentration of the inhibitor. The adsorption of this extract on the copper specimen surface was spontaneous and obeyed the Langmuir’s adsorption isotherm. Large value of adsorption equilibrium Constant (K ads = 35 L g−1) was obtained. The polarization experiments confirmed the data obtained by gravimetric weight-loss. Tafel plot of polarization curves indicates that the extract acts as a mixed type inhibitor.

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RofiaMezaache, Harkat H, Obszynski J, Benkouider A, Blanc A, Weibel J-M, Pale P. Copper(II) bromide as an efficient catalyst for acetal to bisarylmethyl ether interconversion. Tetrahedron Letters [Internet]. 2014;55 (52) :7167-7171. Publisher's VersionAbstract

Transprotection of acetals to bis(methoxyphenyl)methyl (BMPM) ethers can be efficiently achieved in the presence of copper dibromide as catalyst in acetonitrile at room temperature. Acetals are conveniently and selectively converted to the corresponding mono-protected diol with bis(methoxyphenyl)methyl isopropyl ether (BMPMOiPr) as the reagent. This new practical reagent allows the BMPM transfer to 1,3-dioxolanes or 1,3-dioxanes under copper catalysis. The reaction conditions are also very mild and tolerant to various functional groups, including other protecting groups.

RofiaMezaache, Harkat H, Obszynski J, Benkouider A, Blanc A, Weibel J-M, Pale P. Copper(II) bromide as an efficient catalyst for acetal to bisarylmethyl ether interconversion. Tetrahedron Letters. 2014;55 (52) :7167-7171.Abstract

Transprotection of acetals to bis(methoxyphenyl)methyl (BMPM) ethers can be efficiently achieved in the presence of copper dibromide as catalyst in acetonitrile at room temperature. Acetals are conveniently and selectively converted to the corresponding mono-protected diol with bis(methoxyphenyl)methyl isopropyl ether (BMPMOiPr) as the reagent. This new practical reagent allows the BMPM transfer to 1,3-dioxolanes or 1,3-dioxanes under copper catalysis. The reaction conditions are also very mild and tolerant to various functional groups, including other protecting groups.

Specklin S, Gallier F, RofiaMezaache, Harkat H, Dembelé YA, Weibel J-M, Blanc A, Pale P. Copper(II) bromide as efficient catalyst for silyl- to bisarylmethyl ethers interconversion (transprotection). Tetrahedron Letters [Internet]. 2011;52 (44) :5820-5823. Publisher's VersionAbstract

Primary and secondary silylated alcohols are easily converted to bis(methoxyphenyl)methyl (BMPM) ethers in good yields using CuBr2 as catalyst in acetonitrile at room temperature. Various other protecting groups are compatible with this mild and convenient process.

 

Graphical abstract

Primary and secondary silylated alcohols are easily and rapidly converted to bis(methoxyphenyl)methyl (BMPM) ethers in good yields using CuBr2 as catalyst in acetonitrile at room temperature. Various other protecting groups are compatible with this mild and convenient process.

 

Specklin S, Gallier F, Mezaache R, Harkat H, Yénimégué A, Weibel J-M, Blanc A, Pale P. Copper(II) Bromide as Efficient Catalyst for Silyl- to Bisarylmethyl Ethers Interconversion (Transprotection). Tetrahedron Letters [Internet]. 2011;52 (44) :5820-5823. Publisher's VersionAbstract

Primary and secondary silylated alcohols are easily converted to bis(methoxyphenyl)methyl (BMPM) ethers in good yields using CuBr2 as catalyst in acetonitrile at room temperature. Various other protecting groups are compatible with this mild and convenient process.

Graphical abstract

Primary and secondary silylated alcohols are easily and rapidly converted to bis(methoxyphenyl)methyl (BMPM) ethers in good yields using CuBr2 as catalyst in acetonitrile at room temperature. Various other protecting groups are compatible with this mild and convenient process.