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61.
Eno E. Ebenso Taner Arslan Fatma Kandemi̇rlı Ian Love Cemi̇l Öğretır Murat Saracoğlu Savıour A. Umoren 《International journal of quantum chemistry》2010,110(14):2614-2636
Density functional theory (DFT) at the B3LYP/6‐31G (d,p) and BP86/CEP‐31G* basis set levels and ab initio calculations using the RHF/6‐31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap (ΔE), the Mulliken charges on the C, O, N, S atoms, hardness (η), softness (S), polarizability (α), dipole moment (μ), total energy change (ΔET), electrophilicity (ω), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), and the fraction of electrons transferred (ΔN). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the EHOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
62.
Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. For this aim, a series of novel Ru(II) complexes with the P-N-P ligands were synthesized starting from the complex [Ru(η6-p-cymene)(μ-Cl)Cl]2 or [RuCp*Cl(COD)]. The complexes were fully characterized by analytical and spectroscopic methods. 31P-{1H} NMR, DEPT, 1H-13C HETCOR or 1H-1H COSY correlation experiments were used to confirm the spectral assignments. Complexes 5, 6 and 7 catalyze the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of iso-PrOH as the hydrogen source. Catalytic studies showed that all complexes are excellent catalytic precursors for the transfer hydrogenation of acetophenone derivatives in 0.1 M iso-PrOH solution. Notably 5 acts as an excellent catalyst giving the corresponding alcohols in excellent conversions up to 99% (TOF ≤ 492 h−1). 相似文献
63.
Radiation-induced graft polymerization is one of the best methods for obtaining materials with new properties. In this work, radiation grafting of 2-chloroacrylonitrile to cellulose by mutual and pre-irradiation grafting methods was investigated. The grafting yield was enhanced by applying the emulsion grafting method. The grafting yield determined in the above systems was observed as 27% at highest and 6% at lowest. The effects of concentration of monomer, reaction time and reaction temperature on grafting yield were studied. Evidence of grafting has been based on the comparative studies of cellulose and grafted cellulose by infrared spectroscopy, thermal analysis and contact angle measurement. Grafting enhances thermal stability of cellulose backbone. 相似文献
64.
Murat Koparan 《Mathematical Methods in the Applied Sciences》2014,37(18):3008-3012
We perform a multiple‐time scales analysis and compatibility condition to the short‐wave model equation. We derive Korteweg–de Vries flow equation in the bi‐Hamiltonian form as an amplitude equation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
65.
In this study, single stage (SS), double-stage (DS), and gain flattened (GF) DS L-band erbium-doped fiber amplifier (EDFA) configurations are designed in order to obtain a flat gain amplifier. Temperature dependence of the mentioned configurations is also analyzed. Maximum spectral dependence of EDFA gain with respect to temperature is obtained for SS EDFA design while smaller spectral dependence of gains is obtained for both DS and GF DS L-EDFA configurations. It is observed that the maximum temperature dependence is in the range of 1570-1580 nm band for all configurations. It has also been found that for all configurations, reducing the temperature has greater effect than raising the temperature on EDFA gain. The overall results show that a temperature independent L-band configuration has not been possible. However, for some signal wavelengths, the erbium-doped fiber (EDF) lengths at which the gain is temperature independent are observed. 相似文献
66.
Murat Cakici Mustafa Catir Semistan Karabuga Hamdullah Kilic Sabri Ulukanli Medine Gulluce Furkan Orhan 《Tetrahedron: Asymmetry》2010,21(16):2027-2031
A simple synthetic method for the preparation of enantiomerically pure (S)-4-aminoquinazoline alcohols from (S)-quinazolinone alcohols by key steps including chlorination, nucleophilic ipso substitution, and deacetylation is presented. Mutagenic and antimutagenic properties of the (S)-4-aminoquinazoline alcohols were investigated by using Salmonella typhimurium TA1535, and Escherichia coli WP2uvrA tester strains at 0.01, 0.1, and 1 μg/plate concentrations. (S)-4-aminoquinazoline alcohols were found to be genotoxically safe at the tested concentrations. Among the tested (S)-4-aminoquinazoline alcohols, the best antimutagenic activity was obtained with a methyl derivative at 0.1 μg/plate dose. 相似文献
67.
Long Li N. Murat Karabacak Jennifer S. Cobb Qi Wang Pengyu Hong Jeffrey N. Agar 《Rapid communications in mass spectrometry : RCM》2010,24(18):2689-2696
Our previous work postulated a transition concept among different isotopic mass states (i.e., isotopic species) of a molecule, and developed a hierarchical algorithm for accurately calculating their masses and abundances. A theoretical mass spectrum can be generated by convoluting a peak shape function to these discrete mass states. This approach suffers from limited memory if a level in the hierarchical structure has too many mass states. Here we present a memory efficient divide‐and‐recursively‐combine algorithm to do the calculation, which also improves the truncation method used in the previous hierarchical algorithm. Instead of treating all of the elements in a molecule as a whole, the new algorithm first ‘strips’ each element one by one. For the mass states of each element, a hierarchical structure is established and kept in the memory. This process reduces the memory usage by orders of magnitude (e.g., for bovine insulin, memory can be reduced from gigabytes to kilobytes). Next, a recursive algorithm is applied to combine mass states of elements to mass states of the whole molecule. The algorithm described above has been implemented as a computer program called Isotope Calculator, which was written in C++. It is freely available under the GNU Lesser General Public License from http://www.cs.brandeis.edu/~hong/software.html or http://people.brandeis.edu/~agar . Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
68.
69.
The catalytic potential of imidazolium salts in the benzoin condensation was investigated. Various aromatic aldehydes were tested in the benzoin condensation under the optimised protocol to afford α-hydroxyketones using N-heterocyclic carbenes derived from mono- and dicationic imidazolium salts. The products were obtained in good yields within short reaction times. Dicationic imidazolium salts with a long aliphatic chain between the imidazole rings were found to be more effective pre-catalysts for the benzoin condensation in comparison to the corresponding monocationic salts having the same aliphatic chain length. 相似文献
70.
Murat Aydemir Nermin Meric Akın Baysal Bahattin Gümgüm Mahmut Toğrul Yılmaz Turgut 《Tetrahedron: Asymmetry》2010,21(6):703-710
Hydrogen-transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. The new chiral C2-symmetric ligands N,N′-bis-[(1S)-1-sec-butyl-2-O-(diphenylphosphinite)ethyl]ethanediamide, 1 and N,N′-bis-[(1S)-1-phenyl-2-O-(diphenylphosphinite)ethyl]ethanediamide, 2 and the corresponding ruthenium complexes 3 and 4 have been prepared and their structures have been elucidated by a combination of multi-nuclear NMR spectroscopy, IR spectroscopy, and elemental analysis. 1H–31P NMR, DEPT, 1H–13C HETCOR, or 1H–1H COSY correlation experiments were used to confirm the spectral assignments. The catalytic activity of complexes 3 and 4 in transfer hydrogenation of acetophenone derivatives by iso-PrOH has also been studied. Under optimized conditions, these chiral ruthenium complexes serve as catalyst precursors for the asymmetric transfer hydrogenation of acetophenone derivatives in iso-PrOH and act as excellent catalysts, giving the corresponding chiral alcohols in 99% yield and up to 75% ee. This transfer hydrogenation is characterized by low reversibility under these conditions. 相似文献