- Dendrimers: A new class of corrosion inhibitors for mild steel in 1?M HCl: Experimental and quantum chemical studies
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The inhibition properties of two ammonia cored dendrimers have been investigated for mild steel corrosion in 1?M hydrochloric acid solution using chemical, electrochemical, surface and quantum chemical calculation methods. It was observed that inhibition efficiency increases with increasing the concentration of both the dendrimers and maximum efficiency was obtained at 50?ppm (50?mgL??1) concentration. Potentiodynamic study suggested that investigated dendrimers behaved as mixed inhibitors and their adsorption on mild steel surface obeyed the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) examinations of mild steel surface confirmed the inhibition behavior of investigated inhibitor molecules. Atomic force microscopic (AFM) study revealed that studied compounds increases the surface smoothness of AFM micrographs by adsorbing on the metallic surface. Several quantum chemical calculations parameters were calculated and the results obtained were found to be consistent with the experimental findings.
- Verma, Chandrabhan,Ebenso, Eno E.,Vishal, Yeddu,M.A.Quraishi
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- Tripodal trisamides based on nicotinic and picolinic acid derivatives
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A number of polydentate arylamide ligands have been prepared by coupling various acyclic tripodal or linear polyamines with derivatives of nicotinic and picolinic acids. Two synthetic procedures were utilized; tris{[(2-hydroxynicotinyl)carbonyl]-2-aminoethyl}amine (H3NICTREN) was prepared by Method A, the HOSu/DCC method, and the other arylamides in this study were prepared by Method B, the CDI method. Method A involved the reaction of N-hydroxysuccinimide with 2-hydroxynicotinic acid (in the presence of dicyclohexylcarbodiimide (DCC) as a dehydrative coupling reagent) to form the succinimide ester, followed by reaction with TREN to yield H3NICTREN. Method B involved reaction of a carboxylic acid (2-hydroxynicotinic, 3-hydroxypicolinic, nicotinic, or picolinic acids) with carbonyldiimidazole (CDI) to form the N-acylimidazolide, followed by reaction with the amine (TREN, TAME, spermidine, or TRPN) to yield the desired arylamide. The X-ray structure of 1,1,1-tris([(3-hydroxypicolinyl)carbonyl]-2-aminomethyl)ethane (H3PICTAME) was determined; crystals of H3PICTAME are monoclinic, a = 10.257(2), b = 15.572(3), c = 15.208(2) A, β = 96.124(15)°, Z = 4, space group P21/a. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.041 and Rw = 0.038 for 2506 reflections with I ≥gt; 3σ(I). In the solid state, H3PICTAME contains an extensive hydrogen-bonding network, with eight intra- and one intermolecular H-bonds per molecule; the ligand is partially preorganized for metal ion chelation. The acid dissociation constants of H3NICTREN and those of 1,1,1-tris{[(2-hydroxynicotinyl)carbonyl]-2-aminomethyl}ethane (H3NICTAME) have been determined; pKa1 = 11.2 (10.68), pKa2 = 10.7 (10.58), pKa3 = 10.0 (9.71), and pKa4 = 6.25 for H3NICTREN (H3NICTAME); the high phenolic pKa's are consistent with the hydrogen bonding observed in the solid state.
- Hoveyda,Karunaratne, Veranja,Nichols, Christopher J.,Rettig, Steven J.,Stephens, Ashley K. W.,Orvig, Chris
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p. 414 - 425
(2007/10/03)
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- General method for the synthesis of trishydroxamic acids
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Triscarboxylic acids, when treated with hydroxylamines in the presence of water-soluble carbodiimide in THF-H2O, at pH≈4.8, yield the corresponding trishydroxamic acids in good yields.
- Karunaratne,Hoveyda,Orvig
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p. 1827 - 1830
(2007/10/02)
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