- Synthesis and characterization of ionic liquid immobilized on magnetic nanoparticles: A recyclable heterogeneous organocatalyst for the acetylation of alcohols
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Herein, we describe a simple and efficient procedure for the preparation of 3-((3-(trisilyloxy)propyl)propionamide)-1-methylimidazolium chloride ionic liquid supported on magnetic nanoparticle (TPPA-IL-Fe3O4). The structure of this magnetic ionic liquid is fully characterized by FT-IR, TGA, XRD, VSM, SEM, EDX and DLS techniques. TPPA-IL-Fe3O4 is employed as a catalyst for the acetylation of alcohols with acetic anhydride under mild and heterogeneous conditions at room temperature with good to excellent yields. The magnetic catalyst could be readily separate from the reaction media by simple magnetic decantation, and reused several times without significant loss of its catalytic activity.
- Ghorbani-Choghamarani, Arash,Norouzi, Masoomeh
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p. 832 - 840
(2015/11/16)
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- Rice husk ash: A new, cheap, efficient, and reusable reagent for the protection of alcohols, phenols, amines, and thiols
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Amild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields. Copyright
- Shirini,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali
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p. 577 - 586
(2014/06/09)
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- Rice husk: Introduction of a green, cheap and reusable catalyst for the protection of alcohols, phenols, amines and thiols
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A mild, efficient and eco-friendly protocol for the chemoselective protection of benzylic and primary and less hindered secondary aliphatic alcohols and phenols as trimethylsilyl ethers and different types of amines as N-tert-butylcarbamates is developed using rice husk (RiH) as the catalyst. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols and amines with acetic anhydride. Easy work-up, relatively short reaction times, excellent yields and low cost, availability and reusability of the catalyst are the striking features of this methodology, which can be considered to be one of the best and general methods for the protection of alcohols, phenols, thiols and amines. In addition, the use of a green reagent in the above-mentioned reactions results in a reduction of environmental pollution and of the cost of the applied methods.
- Shirini, Farhad,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali,Aliakbar, Ali-Reza
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p. 164 - 170
(2014/03/21)
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- Acetylation of alcohols with acetic anhydride promoted by N,N,N-trimethylanilinium tribromide
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A wide variety of alcohols were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of N,N,N-trimethylanilinium tribromide to produce the corresponding alkyl acetates in good to excellent yields. Following this procedure, acetylation of primary, secondary, and tertiary alcohols has been performed under neutral conditions.
- Ghorbani-Choghamarani,Shiri,Rostami
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p. 1728 - 1730
(2014/08/05)
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- Polyvinylpolypyrrolidone-bound boron trifluoride: A highly efficient catalyst for acylation of alcohols, phenols and trimethylsilyl ethers by acetic anhydride
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A highly efficient method for the acylation of alcohols, phenols and trimethylsilyl ethers with acetic anhydride is described using polyvinylpolypyrrolidone-bound boron trifluoride (PVPP-BF3) under mild and heterogeneous conditions at room temperature in good to excellent yields. The polyvinylpolypyrrolidone-boron trifluoride complex shows more water tolerant, non-corrosive and stable solid catalyst elevated Lewis acid properties.
- Mokhtary, Masoud,Qandalee, Mohammad,Najafizadeh, Faranak
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experimental part
p. 389 - 393
(2012/08/28)
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- H6GeMo10V2O40·16H 2O nanoparticles prepared by hydrothermal method: A new and reusable heteropoly acid catalyst for highly efficient acetylation of alcohols and phenols under solvent-free conditions
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A new Keggin-type heteropoly acid, namely decamolybdodivanadogermanic acid (H6GeMo10V2O40·16H 2O), with nanosized particles (5-8 nm), has been synthesized by a hydrothermal method and characterized by elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and potentiometric titration. H6GeMo10V2O40·16H 2O revealed high catalytic activity for acetylation of various alcohols and phenols with acetic anhydride at room temperature (298 ± 2 K) and under solvent-free conditions. The catalyst can be easily recovered and used repeatedly for five cycles with a slight loss of activity. The catalytic activity of H6GeMo10V2O40· 16H2O was higher than that of other Keggin-type heteropoly acids, such as H3PW12O40, H3PMo 12O40 and H4SiW12O40.
- Farhadi, Saeid,Zareisahamieh, Reza,Zaidi, Masoumeh
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experimental part
p. 1323 - 1332
(2012/04/04)
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- A mild and efficient method for the methoxymethylation and acetylation of alcohols promoted by benzyltriphenylphosphonium tribromide
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A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
- Shirini, Farhad,Imanzadeh, Gholam Hossein,Mousazadeh, Seyyed Ali Reza,Mohammadpoor-Baltork, Iraj,Abedin, Masoumeh
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experimental part
p. 1187 - 1190
(2011/10/05)
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- Lithium trifluoromethanesulfonate (LiOTf) as a recyclable catalyst for highly efficient acetylation of alcohols and diacetylation of aldehydes under mild and neutral reaction conditions
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A variety of alcohols and aldehydes were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of lithium triflate (LiOTf) to produce the corresponding esters and 1,1-diacetates, respectively, in good to excellent yields under essentially neutral reaction conditions. Sensitive functional groups such as PhCO2-, OMe, and OTBDMS ethers survived intact under the described reaction conditions.
- Karimi, Babak,Maleki, Jafar
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p. 4951 - 4954
(2007/10/03)
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- Reductive esterification of aromatic aldehydes using Zn/Ac 2O/imidazole or Zn/Yb(OTf)3/(RCO)2O system
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Benzaldehydes are reduced by metallic zinc in the presence of Ac 2O and imidazole, giving the corresponding benzyl acetates in good yields. Reductive esterification of aromatic aldehydes is also carried out via gem-diacetoxy compounds. Carbonyl compounds are readily converted to the gem-diacyloxy compounds in excellent yields on treatment with 2molar amounts of acid anhydride and 10mol% of Yb(OTf)3 in MeCN at room temperature. Thus-formed diacyloxy compounds derived from aromatic aldehydes are reduced in situ by metallic zinc to afford the corresponding esters.
- Hirao, Toshikazu,Santhitikul, Sirida,Takeuchi, Hiroki,Ogawa, Akiya,Sakurai, Hidehiro
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p. 10147 - 10152
(2007/10/03)
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- Oxidation of Alkylbenzenes by S2O82--CuII in Acetic Acid and Acetonitrile
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Oxidation of a series of toluenes by K2S2O8 or (NH4)2S2O8 + Cu(OAc)2 in acetic acid or acetonitrile is little affected by added water or acetate and gives benzyl acetates or benzaldehydes, respectively, in good yields.Data are consistent with initial formation of aromatic radical cations, proton loss to give benzyl radicals, and oxidation to final products by CuII.Benzyl alcohols, but not acetates, are selectively oxidized, suggesting partial equilibration of radical cations, with rates of proton loss determining product distributions.Oxidation of cumene gives chiefly α-methylstyrene which is oxidized futher to 2-phenylpropanal.Products from p-ethyltoluene and p-cumene indicate that, on a statistical basis, loss of secondary and tertiary protons is more rapid than loss of primary protons, contrary to some previous reports.These systems appear promising for studying fragmentation patterns of aromatic radical cations in general.
- Walling, Cheves,Zhao, Chengxue,El-Taliawi, Gamil M.
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p. 4910 - 4914
(2007/10/02)
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- Unidirectional Dieckmann Cyclizations on a Solid Phase and in Solution
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Dieckmann cyclization of 2percent divinylbenzene-copolystyrene resin alkyl pimelates and analogous benzyl alkyl pimelates is reported.The use of uniquely single-labeled dioate esters has allowed analysis of the direction of closure via decarboxylation of the keto ester products.The influence of steric factors on the competition between enolate condensation and transesterification and upon the direction of closure of the cyclization has been evaluated, and the conditions for achieving >99percent regioselective closure are described.Modifications in the conditions of solid-phase peptide synthesis required for successful high-temperature enolate cyclization have been developed and the results are compared to solution reactions of benzyl alkyl esters under similar conditions.The resin attachment afforded a clear benefit over the benzyl models and greatly simplified isolation and purification of the resulting β-keto esters.
- Crowley, John I.,Rapoport, Henry
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p. 3215 - 3227
(2007/10/02)
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- ELECTRON-TRANSFER PROCESSES. NEW SYNTHESIS OF γ-LACTONES BY PEROXYDISULFATE OXIDATION OF ISOPROPYLBENZENES AND ALIPHATIC CARBOXYLIC ACIDS
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A new synthesis of γ-lactones by peroxydisulfate oxidation of isopropylbenzenes is described.Evidence concerning the free-radical mechanism is reported; the intermediate formation of alkyl and benzyl radicals is evidenced by trapping them with quinoxaline.The role of the iron catalyst is discussed.
- Giordano, Claudio,Belli, Aldo,Citterio, Attilio,Minisci, Francesco
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p. 3559 - 3562
(2007/10/02)
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