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821.
A new diamine, 1,5-bis(2-amino-4-trifluoromethylphenoxy)naphthalene (DA1524) was synthesized by the nucleophilic substitution reaction of 1,5-dihydroxynaphthalene and 4-chloro-3-nitrobenzotrifluoride in the presence of potassium carbonate in N,N-dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C in ethanol. DA1524 was then utilized to prepare a novel class of CF3-containing polyimides. Intrinsic viscosities [η] of the polymer solutions at 25 °C were measured by the extrapolation of their viscosity numbers till zero concentration. and values of the resulting polymers were determined using gel-permeation chromatography (GPC). The polymers showed a good film-forming ability, and some characteristics of their thin films including color and flexibility were investigated qualitatively. In addition, the absorption edge values (λ0) obtained from their UV–vis curves were determined, and all the resulting polyimides films exhibited high optical transparency. Thermal stability of the polymers was investigated using TGA analyses. The Tg values of the polyimides obtained from their DSC plots were quantified. Solubility of the samples in a variety of organic solvents was also tested. 相似文献
822.
Ali Haghtalab Abolfazl Shojaeian Seyed Hossein Mazloumi 《The Journal of chemical thermodynamics》2011,43(3):354-363
An electrolyte activity coefficient model is proposed by combining non-electrolyte NRTL-NRF local composition model and Pitzer–Debye–Hückel equation as short-range and long-range contributions, respectively. With two adjustable parameters per each electrolyte, the present model is applied to correlation of the mean activity coefficients of more than 150 strong aqueous electrolyte solutions at 298.15 K. Also the results of the present model are compared with the other local composition models such as electrolyte-NRTL, electrolyte-NRTL-NRF and electrolyte-Wilson-NRF models. Moreover, the present model is used for prediction of the osmotic coefficient of several aqueous binary electrolytes systems at 298.15 K. Also the present activity coefficient model is adopted for representation of nonideality of the acid gases, as weak gas electrolytes, soluble in alkanolamine solutions. The model is applied for calculation of solubility and heat of absorption (enthalpy of solution) of acid gas in the two {(H2O + MDEA + CO2) and (H2O + MDEA + H2S)} systems at different conditions. The results demonstrate that the present model can be successfully applied to study thermodynamic properties of both strong and weak electrolyte solutions. 相似文献
823.
Mehdi Bakavoli Mohammad Rahimizadeh Ali Shiri Hossein Eshghi Parvaneh Pordeli Mehdi Pordel Mohsen Nikpour 《Journal of heterocyclic chemistry》2011,48(1):149-152
Several derivatives of the new pyridazino[4,3‐e][1,3,4]oxadiazine ring system were prepared, and their antibacterial evaluations were performed on four different Gram‐negative and Gram‐positive bacteria. J. Heterocyclic Chem., (2010). 相似文献
824.
A series of new Schiff base polyamides(PAs) were synthesized by polycondensation of benzilbisthiosemicarbazone diamine(LH6) with different commercially available aliphatic and aromatic diacid chlorides. The monomer and all the PAs were characterized by FTIR,1H-NMR,and elemental analysis.The prepared polyamides showed inherent viscosities in the range of 0.30-0.36 dL/g in DMF at 25℃,indicating their moderate molecular weight.The PAs were completely soluble in aprotic polar solvents such as dimethylformamide(DMF),N-methylpyrolidone(NMP), tetrachloroethane(TCE),dimthylsulfoxide(DMSO) and also in H2SO4 and partially soluble in THF,acetone and chloroform at room temperature.Thermal analysis showed that these PAs were practically amorphous and exhibited 10%weight loss above 220℃. 相似文献
825.
Abstract
Experimental densities ρ, viscosities η, and refractive indices n D of the ternary mixtures consisting of 2-methyltetrahydrofuran + chlorobenzene + cyclopentanone and constituted binary mixtures were measured at T = 298.15 K for the liquid region and at ambient pressure for the whole composition range. Excess molar volumes V\textm\textEV_{\text{m}}^{\text{E}}, deviations in the viscosity Δη, and deviations in the refractive index Δn D from the mole fraction average for the mixtures were derived from the experimental data. The excess partial molar volumes V\textm,i\textEV_{{\text{m}},i}^{\text{E}} were also calculated. The binary and ternary data of V\textm\textEV_{\text{m}}^{\text{E}}, Δη, and Δn D were correlated as a function of the mole fraction by using the Redlich–Kister and the Cibulka equations, respectively. McAllister’s three-body interaction model is used for correlating the kinematic viscosity of binary mixtures with the mole fraction. 相似文献826.
827.
Tavakol H Esfandyari M Taheri S Heydari A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(3):574-582
In this work, two important opioid antagonists, naltrexone and oxycodone, were prepared from thebaine and were characterized by IR, (1)H NMR and (13)C NMR spectroscopy. Moreover, computational NMR and IR parameters were obtained using density functional theory (DFT) at B3LYP/6-311++G** level of theory. Complete NMR and vibrational assignment were carried out using the observed and calculated spectra. The IR frequencies and NMR chemical shifts, determined experimentally, were compared with those obtained theoretically from DFT calculations, showed good agreements. The RMS errors observed between experimental and calculated data for the IR absorptions are 85 and 105 cm(-1), for the (1)H NMR peaks are 0.87 and 0.17 ppm and for those of (13)C NMR are 5.6 and 5.3 ppm, respectively for naltrexone and oxycodone. 相似文献
828.
Marjani K Mousavi M Nahzomi HT Arazi O Jafari R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1798-1802
The restricted rotation of p-tolyl moiety in 5,5-dimethyl-3,4-di-p-tolyl-2-cyclopenten-1-one was studied by variable temperature NMR spectroscopy at a temperature range of 218-368 K. A free rotation, in NMR time scale, was observed at temperatures higher than 368 K; while, the rotation froze below 248 K. From dynamic NMR analysis, the Arrhenius energy of activation ΔG? was calculated as 56.37 kJ mol(-1). The experimental results were confirmed by theoretical calculation using the density functional theory method B3LYP with basis sets, 6-31G and 6-31+G. 相似文献
829.
In this paper, electrical and structural properties of mono-, di-, tri- and tetrachlorothiophenes and their radical cations
have been studied using the density functional theory and B3LYP method with 6-311++G** basis set. The effects of the number
and position of the substituent of chlorine atoms on the properties of the thiophene ring for all chlorothiophenes and their
radical cations have been studied. Vibrational frequencies, nuclear chemical shielding constants, spin-density distribution,
size and direction of dipole moment vector, ionization potential, electric polarizabilities and NICS values of these compounds
have been calculated as well. The analysis of these data showed that double bonds in 3-chlorothiophene are more delocalized
and it is the best possible candidate monomer among all chlorothiophenes for the synthesis of corresponding conducting polymers
with modified characteristics. 相似文献
830.
Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated
by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating
agent and thiourea as sulfur source. The resulting S-doped Nb2O5 nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy
(EDAX), scanning electron microscope (SEM), ultra-violet diffuse reflectance (UV-DRS) and thermogravimetry thermal Analysis
(TG-DTA). As against the response of unmodified niobium(V) oxide nanoparticles (UNON), the doped samples show different electrochemical
response indicating an induced charge transfer across the niobium pentoxide/solution interface, thus forming two anodic peaks
and a cathodic peak. This important observation was confirmed by UV-DRS in terms of band bending due to sulfur doping. Upon
sulfur-modification, the absorption edge extends into the visible light region. The SEM observation shows that the SNPN existed
in the mode of polycrystalline structure and the average grain size 63 nm. The EDAX analysis of undoped Nb2O5 and sulfur doped Nb2O5 shows the Nb2O5 (98%) and S (2%) content of nanopowder. These SNON nanoparticles are expected to be suitable candidates as visible light
niobium(V) oxide nanoparticles sensitization. 相似文献