共查询到20条相似文献,搜索用时 15 毫秒
1.
Jinming Zhang Jin Wu Yan Cao Shengmei Sang Jun Zhang Jiasong He 《Cellulose (London, England)》2009,16(2):299-308
The ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a reaction medium was studied for the synthesis of cellulose
benzoates by homogeneous acylation of dissolved cellulose with benzoyl chlorides in the absence of any catalysts. Cellulose
benzoates with a degree of substitution (DS) in the range from about 1 to 3.0 were accessible under mild conditions. The DS
of cellulose derivatives increased with the increase of the molar ratio of benzoyl chloride/anhydroglucose unit (AGU) in cellulose,
reaction time, and reaction temperature. Benzoylation of cellulose with some 4-substituted benzoyl chlorides including 4-toluoyl
chloride, 4-chlorobenzoyl chloride and 4-nitrobenzoyl chloride was also readily carried out under mild conditions. Furthermore,
regioselectively substituted mixed cellulose esters were synthesized in this work. All products were characterized by means
of FT-IR, 1H-NMR, and 13C-NMR spectroscopy. In addition, at the end of benzoylation of cellulose, the ionic liquid AmimCl was easily recycled. When
the recycled AmimCl was used as the reaction media, the cellulose benzoate with a similar DS was obtained under comparable
reaction conditions. 相似文献
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Barahman Movassagh Mohammad Soleiman-Beigi 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):409-411
Abstract A simple, highly efficient, and green protocol has been developed for preparation of sulfides from alkyl or aryl thiols and
benzyl-, allyl-, t-butyl, and adamantyl halides under solvent- and catalyst-free conditions.
Graphical abstract
相似文献
4.
Toru Sugihara 《Tetrahedron letters》2005,46(48):8269-8271
The Mizoroki-Heck type arylation of alkenes with aroyl chlorides accompanied by decarbonylation efficiently proceeds in the presence of a palladium catalyst system, PdCl2(PhCN)2/(PhCH2)Bu3NCl, even without adding any base. The products can be isolated by a very simple procedure. 相似文献
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Samuel ThurowVanda A. Pereira Débora M. MartinezDiego Alves Gelson PerinRaquel G. Jacob Eder J. Lenardão 《Tetrahedron letters》2011,52(5):640-643
We present here the results on the use of 1-n-butyl-3-methylimidazolium methylselenite, [bmim][SeO2(OCH3)], in the synthesis of symmetrical disulfides starting from thiols. This efficient and improved method is general for aromatic, aliphatic, and functionalized thiols affording the disulfides in good to excellent yields after easy work up. The use of a microwave accelerates the reaction and the [bmim][SeO2(OCH3)] was reused for further oxidation reactions. 相似文献
7.
Although quaternary onium salt-catalyzed phase-transfer reactions are generally believed to require base additives, we discovered even without any base additives conjugate additions of 3-substituted oxindoles proceeded smoothly in the presence of lipophilic quaternary onium bromide under water-organic biphasic conditions. The mechanism of this novel base-free neutral phase-transfer reaction system was investigated, and the assumed catalytic cycle was presented together with interesting effects of water and lipophilicity of the phase-transfer catalyst. The base-free neutral phase-transfer reaction system could be applied to highly enantioselective conjugate additions, aldol reaction, sulfenylation, and chlorination under the influence of chiral bifunctional onium bromides as key catalysts. 相似文献
8.
Márcio S. Silva 《Tetrahedron letters》2008,49(12):1927-1930
We present here a clean, solvent-free hydrothiolation of alkynes using solid supported catalyst (Al2O3/KF). This efficient and improved method selectively furnishes the corresponding anti-Markovnikov vinyl sulfides in good to excellent yields. The method is applicable for aliphatic and aromatic thiols and the catalytic system can be re-used up to two times without previous treatment and with comparable activity. 相似文献
9.
A new type of ionic liquid supported selenium reagents were synthesized and found to be an excellent catalyst in the oxidation of alcohols to aldehydes and ketones in the presence of 30%H2O2.The predictable solubility of ionic liquids allows an easy separation of the oxidation products from the reaction mixture.Furthermore,the oxidation reaction can be carried out using an ionic liquid as the solvent,and the ionic liquid-supported selenium reagents can be recycled and used for four times with a little decrease in catalytic performance. 相似文献
10.
The synthesis of unsymmetrical sulfides has been achieved in good to excellent yields with inexpensive ethyl potassium xanthogenate via cross-coupling reaction using recyclable CuO nanoparticles under ligand-free conditions.The copper oxide nanoparticles can be recovered and reused up to five cycles without loss of activity. 相似文献
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Miao CX Wang JQ Yu B Cheng WG Sun J Chanfreau S He LN Zhang SJ 《Chemical communications (Cambridge, England)》2011,47(9):2697-2699
The first bimagnetic ionic liquid based on Fe and TEMPO with cooperative functionalities not only exhibited strong paramagnetic behaviour at room temperature under an applied magnetic field of 5000 Oe but also proved to be an effective catalyst for selective aerobic oxidation of aromatic alcohols under mild and clean conditions. 相似文献
13.
Anurag Krishna Cosmin Laslau Geoffrey I. N. Waterhouse Zoran D. Zujovic Jadranka Travas-Sejdic 《Chemical Papers》2013,67(8):995-1001
This study investigates the effect of the ionic liquid 1-butyl-3-methyl imidazolium chloride ([bmim]Cl) on the morphological, structural, and electronic properties of polyaniline (PANI) products synthesised by the falling-pH method. Products were characterised by SEM, FT-IR, UVVIS, N2-physisorption, and conductivity measurements. The [bmim]Cl addition strongly influenced the PANI morphology, specific surface area, porosity, and conductivity. Depending on the [bmim]Cl: ANI ratio and the synthesis pH, a wide range of PANI nanostructures could be prepared, with rod-like, and fibre-like elongated structures being the dominant morphology under most experimental conditions. Samples prepared in the presence of [bmim]Cl exhibit specific areas of ca 22–35 m2 g?1. The conductivity of the final products depends on the [bmim]Cl: ANI ratio. Temperature dependence of conductivity in the temperature range from 77 K to 300 K was also studied. 相似文献
14.
Highly stable, aqueous dispersions, and hydrophilic ionic liquid-capped silver nanoparticles with positive surface charge were synthesized by in situ reduction of AgNO3 with NaBH4 in the presence of an imidazolium-based ionic liquid, viz., 1-dodecyl-3-methylimidazolium chloride ([C12mim][Cl]) at room temperature. Prepared silver nanoparticles were characterized by UV–vis spectra, transmission electron microscopy (TEM), and zeta potential. UV–visible spectrum of the aqueous medium peaked at 407 nm corresponding to the plasmon absorbance of silver nanoparticles. TEM analysis revealed the spherical shape of the particles with sizes about 9 nm and low polydispersed. The surface charge of the synthesized silver nanoparticles was determined as +5.0 mV. The ionic liquid ([C12mim][Cl]) capped silver nanoparticles were stable for at least 8 months. 相似文献
15.
《Green Chemistry Letters and Reviews》2013,6(3):249-256
Abstract An incredibly elementary procedure for the effective synthesis of 1,5-benzodiazepine derivatives using triethyl ammonium acetate (TEAA) [Et3NH][CH3COO] ionic liquid has been developed. TEAA was found to be practical, inexpensive, reusable and has a simple work-up procedure, which is absent in other catalyst. The role of TEAA as the reaction medium as well as the catalyst has shown the benefits of the use of TEAA in organic synthesis. The effect of [Et3NH][CH3COO] on the synthesis of 1,5-benzodiazepine derivatives has been studied and results are provided herein. 相似文献
16.
[reaction: see text] We report a method for the synthesis of vinyl sulfides using the soluble copper(I) catalyst [Cu(phen)(PPh3)2]NO3. The desired vinyl sulfides are obtained in good to excellent yields, with retention of stereochemistry. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives. 相似文献
17.
Derivatives of fluorine-containing 3-(methoxycarbonylmethylthio)acrylic acids readily undergo base-catalyzed cyclization to form 3-hydroxy- and 3-aminothiophenes. 相似文献
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《Journal of solid state chemistry》1986,65(3):392-395
Titanium sulfides were synthesized in the temperature range 600–750°C and in the pressure range 10–200 MPa with an apparatus used for hydrothermal synthesis. Stoichiometric TiS2 cannot be prepared under atmospheric pressure, but was synthesized under high pressure. Also the phase relationship between TiS2 and TiS3 has been established under high pressure up to 200 MPa, and the pressure-temperature phase diagram for TiS system is presented. 相似文献