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81.
Mehrdad Mahkam Mohammad Galeh Assadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):842-847
A series of acrylic copolymers containing silyl pendant groups was prepared by free radical cross-linking copolymerization. Me3Si, Et3Si, and Ph3Si together with cubane-1,4-dicarboxylic acid (CDA) were covalently linked with 2-hydroxyethyl methacrylate (HEMA). CDA linked to two HEMA group is the cross-linking agent (CA). Free radical cross-linking copolymerization of the methacrylic acid (MAA) and organosilyl monomers with two different molar ratios of CA was carried out at 60–70°C. The compositions of the cross-linked three-dimensional polymers were determined by FT-IR spectroscopy. The glass transition temperature of the network polymers was determined calorimetrically. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). A model hydrophobic drug, the steroid hormone estradiol, was entrapped in these gels, and the in vitro release profiles were established separately in both SGF (pH 1) and SIF (pH 7.4). Incorporation of silyl groups in a new macromolecule system modified network polymers for drug delivery. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
82.
Kazem D. Safa Fatemeh Mosleh Parvaneh Kalantarzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1261-1268
The silanol (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH has been shown to isomerize to (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) when it was kept at room temperature for 10 h in 0.2 M NaOMe/MeOH. Corresponding isomerizations of the above silanol (to give (Me 3 Si) 2 CHSi(C 6 H 4 Me- p ) (Me)(OSiMe 3 )) are complete after 26 h under reflux in pyridine. The reaction involve 1,3-migration from carbon to oxygen within a silanolate ion to give a carbanion, which rapidly acquires a proton from the solvent. Treatment of (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH with MeLi in Et 2 O/THF give, by the same rearrangement, the organolithium reagent (Me 3 Si) 2 CLiSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) which on treatment with Me 2 SiHCl gives (Me 3 Si) 2 C(SiMe 2 H)Si(C 6 H 4 Me- p )(Me)(OSiMe 3 ) and (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). When the experiment was repeated, but with Me 3 SiCl in place of Me 2 SiHCl, it gives exclusively (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). Treatment of the organolithium reagent (Me 3 Si) 2 CLiSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) with Mel gives exclusively (Me 3 Si) 2 CMeSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). The related iodide (Me 3 Si) 3 CSi(C 6 H 4 Me- p )Mel reacts with ICI and IBr to give rearranged (Me 3 Si) 2 C(SiMe 2 X)Si(C 6 H 4 Me- p )Me 2 and unrearranged products (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeX, (X = Cl, Br) respectively. The rearranged bromide (Me 3 Si) 2 C(SiMe 2 Br)Si(C 6 H 4 Me- p )Me 2 reacts with a range of silver [I] salts AgY (Y = OOCCH 3 , SO 4 2 m ) and Mercury [II] salt HgY 2 (Y = OOCCH 3 , SO 4 2 m ) in glacial CH 3 COOH to give the corresponding species (Me 3 Si) 2 C(SiMe 2 OOCCH 3 )Si(C 6 H 4 Me- p )Me 2 . The reaction of the bromide with AgBF 4 in MeOH or i -PrOH give the corresponding rearranged products (Me 3 Si) 2 C(SiMe 2 Y)Si(C 6 H 4 Me- p )Me 2 (Y = --OMe, --OPr i ). 相似文献
83.
Mojtaba Abbasian Nafiseh Khakpour Aali Solmaz Esmaeily Shoja 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):966-975
A method to prepare zinc oxide (ZnO) nanoparticles with a covalently bonded poly(methyl methacrylate) (PMMA) shell by surface initiated atom transfer radical polymerization (ATRP) was reported. First, the initiator for ATRP was covalently bonded onto the surface of zinc oxide nanoparticles through our novel method. Firstly, the surface of ZnO nanoparticle was treated with 3-aminopropyl triethoxysilane, a silane coupling agent, and then this functionalization nanoparticle was reacted with α-chloro phenyl acetyl chloride to prepare atom transfer radical polymerization macroinitiator. The metal-catalyzed radical polymerization of MMA with ZnOmacroinitiator was performed using a copper catalyst system to give the ZnO-based nanoparticles hybrids linking PMMA segments (poly (methyl methacrylate)/zinc oxide nanocomposite). These hybrid nanoparticles had an exceptionally good dispersability in organic solvents and were subjected to detailed characterization using FTIR, TEM and TGA and DSC analyzed. 相似文献
84.
Mir Reza Majidi Reza Fadakar Bajeh Baj Abdolhossein Naseri 《Central European Journal of Chemistry》2013,11(7):1172-1186
Room temperature 1-butyl-3-methylimidazolium tetraflouroborate ([BMIM][BF4]) ionic liquid was employed for dispersion of multi walled carbon nanotubes (MWCNTs) and the formation of nanocomposite on the surface of a carbon-ceramic electrode. The surface of the modified electrode was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The modified electrode exhibited excellent electrochemical activity to oxidation of dopamine (DA); whereas electro oxidation of ascorbic acid (AA) was not seen and electro oxidation of uric acid (UA) appeared at a more positive potential than DA. The multi walled carbon nanotube-ionic liquid nanocomposite modified carbon-ceramic electrode was used for the selective determination of DA in the presence of high levels of AA and UA using differential pulse voltammetry. The calibration curve for DA was linear in the range of 3.00 to 130 µM with the detection limit (S/N=3) of 0.87 µM. The present electrode was successfully applied to the determination of DA in some commercial pharmaceutical samples and human blood serum. 相似文献
85.
The paper presents a new method based on simultaneous derivatization and air-assisted liquid–liquid microextraction (AALLME) for the extraction and preconcentration of some aliphatic amines prior to gas chromatography-flame ionization detection (GC-FID). Primary aliphatic amines are derivatized and extracted simultaneously by a fast reaction with butylchloroformate (derivatization agent/extraction solvent) under mild conditions. The mixture of butylchloroformate and aqueous sample solution is rapidly sucked into a 10-mL glass syringe and then is injected into a test tube with conical bottom and the procedure is repeated seven times. After centrifuging the resulted cloudy solution, the derivatized analytes in the sedimented phase are determined by GC-FID. The influence of main factors on the efficiency of derivatization/extraction procedure is studied. Under the optimal conditions, the enrichment factors (EFs) for aliphatic amines are obtained in the range of 248–360 and limits of detection (LODs) are between 0.30 and 2.6 μg L−1. The obtained extraction recoveries ranged from 50 to 72% and the relative standard deviation (RSD) was less than 4.8% for intra-day (n = 6) and inter-days (n = 4) precision. The method is successfully applied to determine some aliphatic amines in environmental water samples. 相似文献
86.
Mahrokh Baghershiroudi 《合成通讯》2013,43(22):2888-2898
In this work, the use of Fe3O4/geraphene oxide nanocomposite as an efficient catalyst for the synthesis of 5-sulfanyltetrazole derivatives of indoles, pyrroles, and 5-alkyl sulfanyltetrazoles is described. These compounds are readily obtained by the reaction of the starting heterocycles indoles, N-aryl pyrroles, alkyl thiocyanates, and trimethylsilyl azide in good to excellent yields. Moreover, Fe3O4/GO nanocomposite could be easily separated from the reaction mixtures by an external permanent magnet and reused at least six times continuously without significant reduction in the product yield and its catalytic activity. 相似文献
87.
An efficient, solid‐catalyst‐mediated Hantzsch synthesis of 1,4‐dihydropyridines is described. This procedure has such advantages as short reaction time, high yields, and simple workup. The catalyst could be reused several times and keeps its initial activity in the subsequent reactions. 相似文献
88.
Kazem D. Safa Aynaz Feyzi Maryam Allahvirdinesbat Leila Sarchami Parvaneh Nakhostin Panahi 《合成通讯》2013,43(3):382-390
An efficient four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles is described by one-step condensation of an aldehyde, benzil, ammonium acetate, and primary aromatic amine with nanostructure Fe-Cu/ZSM-5 bimetallic oxides in water under ultrasonic irradiation. The short reaction time, good yields, environmental friendly procedure, mild reaction conditions, and convenient operation are important advantage of this protocol. The products generated during the study have been utilized as substrates for synthesis of organosilicon-containing imidazoles. Synthesis of tris(triorganosilyl)methylimidazole derivatives were carried out using organolithium reagent (Me3Si)3CLi, prepared via metalation of (Me3Si)3CH with methyllithium in tetrahydrofuran, in excellent yields. 相似文献
89.
An extremely efficient heterogeneous protocol is reported for the one-pot, three-component synthesis of a series of dihydropyrimidinones (DHPMs) in the presence of ZnO nanoparticles in water as a green solvent. The ZnO nanoparticles exhibited excellent catalytic activity and the proposed methodology is capable of providing the desired products in good yields (65–94%) within short reaction times. After the reaction course, ZnO nanoparticles can be recycled and reused without any apparent loss of activity, which makes this ecofriendly process cost-effective. 相似文献
90.
The solubilities of two cinnamic acid derivatives, namely p-coumaric acid and caffeic acid, in six 1-alkyl-3-methyl imidazolium based ionic liquids composed of the PF6−, BF4−, TFO− and TF2N− anions, and in two organic solvents, t-pentanol and ethyl acetate, have been measured at the temperature range of about (303 to 317) K. The p-coumaric acid was found to be more soluble than caffeic acid in all studied solvents. Higher solubilities of both acids were observed in the ionic liquids composed of the BF4− and TFO− anions. The increase of the alkyl chain length on the cation invokes a decrease in solubility in the case of hydrophilic ionic liquids composed of BF4− anion, while in the case of hydrophobic ones composed of PF6− anion an increase in the solubility is observed. Between the two organic solvents t-pentanol is better solvent than ethyl acetate for both acids. Moreover, using the van’t Hoff equations the apparent Gibbs energy, enthalpy, and entropy of solution were calculated. Finally, successful correlation of the experimental data was achieved with the UNIQUAC and the NRTL activity coefficient models, while poor predictions of the solubility of the two acids in the organic solvents were obtained with two UNIFAC models. 相似文献