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961.
Natalia Hassan Pedro V. Verdes Juan M. Ruso 《The Journal of chemical thermodynamics》2011,43(3):399-404
The thermal denaturation of ovalbumin, lysozyme, myoglobin and fibrinogen at different BTS concentrations have been investigated using differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy. Thermodynamic parameters: melting temperatures (Tm), calorimetric enthalpy (ΔH), van’t Hoff enthalpy (ΔHv) were obtained for all the systems under study. Thermal denaturation of the four proteins was completely irreversible. Changes in the protein conformation due to the adsorption of BTS molecules have been monitored by using UV-CD spectra. Greater changes in α-helical contents correspond with the BTS higher concentrations. The lysozyme denaturation temperature increases at low concentrations BTS indicating that BTS acts as a structure stabilizer; meanwhile it acts as a destabilizer at higher concentrations in all the proteins studied. The major effect is observed in the case of myoglobin, the protein with the highest α-helical secondary structure (75%). 相似文献
962.
2,4,6-Tribromo-1,3,5-trihydroxybenzene (TBTHB) as a reagent was efficiently reacted with 6 molar equivalents of benzothioamides in dimethyl sulfoxide (DMSO), and the corresponding 3,5-diaryl-1,2,4-thiadiazoles were obtained in almost quantitative yields (91–98%) and in short times (15–20 min) with the formation of hexahydroxybenzene as a rather valuable by-product. 相似文献
963.
Hassan Hosseini-Monfared Afsaneh Farrokhi Sohaila Alavi Peter Mayer 《Transition Metal Chemistry》2013,38(3):267-273
A mononuclear dioxo vanadium(V) complex of a hydrazone ONO donor ligand, [VVO2(L1)] (1), was synthesized by the reaction of V2O5 and terephthalic acid with H2L1 in 1:1:1 mol ratio, while an oxo-bridged bis(vanadium(IV)oxo) complex, [μ 2–O–{VIVO(L2)}2] (2), was synthesized by the treatment of isonicotinic acid hydrazide, salicylaldehyde and CoSO4·7H2O with bis(acetylacetonato)oxovanadium(IV) (H2L1 = isonicotinic acid(2-hydroxy-benzylidene)-hydrazide, H2L2 = isonicotinic acid (1-methyl-3-oxo-butylidene)-hydrazide). The complexes were characterized by elemental analyses and spectroscopic methods. The crystal structure of complex 2 was determined by X-ray analysis. The complexes were tested as catalysts for the oxidation of cycloalkenes and benzyl alcohol using H2O2 as terminal oxidant. Excellent selectivity was achieved in the oxidation of cyclohexene. 相似文献
964.
Asmaa A. Magd El-Din Salwa A. Elsharabasy Aisha Y. Hassan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):407-412
Abstract Several new imidazo[2,1-b]-1,3-thiazine derivatives 4a–c, 8a–c, and 11a–c were synthesised via the reaction of 5,5-diphenyl-2-thiohydantoin (1) with αβ -unsaturated nitriles 2a–c, 5a–c, and 9a–c. The structures of the products were established on the basis of elemental analyses, IR, and 1H-NMR spectral data. 相似文献
965.
Habib Firouzabadi Nasser Iranpoor Hassan Hazarkhani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2571-2577
Trichloroisocyanuric acid has been used as a mild, efficient, and new catalyst for transthioacetalization of diacetals of 2,2-bis (hydroxymethyl)-1,3-propanediol in CH 2 Cl 2 at room temperature. A clean, easy, and general method for efficient deprotection of thioacetals to their corresponding carbonyl compounds using trichloroisocyanuric acid/silica gel and water system also is described. 相似文献
966.
Saber M. Hassan Ahmed A. El-Maghraby Mahmoud M. Abdel Aal Mahmoud S. Bashandy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):291-308
4-(5-Amino-4-cyano-1-p-tolyl-1H-pyrrol-3-yl)-N,N-dimethyl-benzenesulfonamide (4) was prepared and converted to several pyrrolo[2,3-d]pyrimidin-5-yl)-N,N-dimethyl-benzenesulfonamide derivatives (5,7,9, and 13). Cyclocondensation of 13 with different electrophilic carbon reagents afforded several 4-(N,N-dimethylaminosulfonylphenyl)]pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]-pyrimidine derivatives (14–17,19, and 20); IR, 1HNMR, and mass spectra of the newly synthesized compounds were recorded. Most of the obtained compounds were screened against Gram-positive and Gram-negative bacteria and fungi, for which some of these derivatives gave promising results. 相似文献
967.
968.
Hassan Keypour Mohammad Hassan Zebarjadian Majid Rezaeivala Mojtaba Shamsipur Seyyed Javad Sabounchei 《Journal of the Iranian Chemical Society》2013,10(6):1137-1143
Lithium-7 NMR spectroscopy was used to investigate the stoichiometry and stability of a Li+ complex with N1,N2-bis(pyridin-2-ylmethylene)ethane-1,2-diamine (L1), N1,N3-bis(pyridin-2-ylmethylene)propane-1,3-diamine (L2) and N1,N4-bis(pyridin-2-ylmethylene) butane-1,4-diamine (L3) in acetonitrile (AN) and nitromethane (NM) solutions. A competitive 7Li NMR method was also employed to probe the complexation of Mn2+, Cd2+ and Zn2+ ions with L1, L2 and L3 in the same solvents. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In both solvents, the stability of the resulting 1:1 complexes were found to vary in the order Zn2+>Cd2+>Mn2+>Li+. In addition, the stability of M–L complexes of M2+ with the Schiff base ligands found to vary in the order M2+–L1 > M2+–L2 > M2+–L3. 相似文献
969.
Modern Friedel–Crafts Chemistry. Part 37. Efficient Syntheses of Some New Julolidines via Cyclialkylations of Heteroaryl Carbinols 下载免费PDF全文
Hassan A. K. Abd El‐Aal Ali A Khalaf Ahmed M. A El‐Khawaga 《Journal of heterocyclic chemistry》2014,51(1):262-268
A simple and convenient procedure for the synthesis of some novel alkyl‐substituted and aryl‐substituted julolidines is reported. Julolidines were smoothly synthesized in excellent isolated yields via Friedel–Crafts intramolecular alkylations of heteroarylalkanols in the presence of both Brønsted (PPA) and Lewis (AlCl3/CH3NO2) acid catalysts. The precursors alkanols, 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , were readily prepared both by reaction of selectively synthesized carboxylic acid esters and ketones with different Grignard reagents and also by reduction of the synthesized ketones with LAH. A plausible carbocation mechanism is proposed to account for the results. The structures of the compounds are established using both spectral and analytical data. 相似文献
970.
Recent Heterocyclic Compounds from (1,3‐Dioxo‐2,3‐dihydro‐1H‐inden‐2‐ylidene)propanedinitrile 下载免费PDF全文
This review summarizes the literatures dealing with the synthesis of some important nitrogen or nitrogen/sulfur heterocyclic, spiroheterocyclic, and fused heterocyclic compounds. 相似文献