- Synthesis and characterization of a bifunctional nanomagnetic solid acid catalyst (Fe3O4@CeO2/SO42?) and investigation of its efficiency in the protection process of alcohols and phenols via hexamethyldisilazane under solvent-free conditions
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In this research, Fe3O4@CeO2 (FC) was synthesized using the coprecipitation method and functionalized by an ammonium sulfate solution to achieve a heterogeneous solid acid Fe3O4@CeO2/SO42? (FCA) catalyst. The synthesized bifunctional catalyst was used in the protection process of alcohols and phenols using hexamethyldisilazane (HMDS) at ambient temperature under solvent-free conditions. Due to its excellent magnetic properties, FCA can easily be separated from the reaction mixture and reused several times without significant loss in its catalytic activity. Excellent yield and selectivity, simple separation, low cost, and high recyclability of the nanocatalyst are outstanding advantages of this procedure. The characterization was carried out using different techniques such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM).
- Mohammadiyan, Esmaeel,Ghafuri, Hossein,Kakanejadifard, Ali
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p. 171 - 178
(2018/09/12)
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- A simple and efficient room temperature silylation of diverse functional groups with hexamethyldisilazane using CeO2 nanoparticles as solid catalysts
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In this study, a mild and efficient method is developed for the silylation of diverse functional groups using CeO2 nanoparticles (n-CeO2) as solid catalysts with hexamethyldisilazane (HMDS) as silylating agent at room temperature. Alcohols, phenols and acids are silylated to their respective silyl derivatives with faster reaction rate while amines and thiols required relatively longer reaction time. Moreover, the solid catalyst is easily be separated from the reaction mixture and recycled more than five times without any obvious decay in its activity. Powder X-ray diffraction (XRD), transmission electron microscope (TEM), UV–vis diffuse reflectance spectra (UV-DRS) and Raman analyses revealed identical structural integrity, particle size, absorption edge and valence state for the reused solid compared to the fresh solid catalyst.
- Anbu, Nagaraj,Vijayan, Chellappa,Dhakshinamoorthy, Amarajothi
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- Nano Fe3O4@ZrO2/SO42?: A highly efficient catalyst for the protection and deprotection of hydroxyl groups using HMDS under solvent-free condition
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In this work, we introduce a new procedure for the protection and deprotection process of various types of alcohols and phenols by HMDS in the presence of nano magnetic sulfated zirconia (Fe3O4@ZrO2/SO42?) as a solid acid catalyst under very mild and solvent-free condition. This method has interesting advantages like short reaction times and a simple workup process. With regard to some outstanding benefits of this new heterogeneous catalyst such as excellent yield, reusability of the catalyst and easy thermal stability, high acidity, strong and excellent magnetic properties, this method can be very interesting in aspect of green chemistry Principles.
- Ghafuri, Hossein,Paravand, Fatemeh,Rashidizadeh, Afsaneh
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supporting information
p. 129 - 135
(2016/12/24)
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- Highly efficient and chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable electron-deficient [TiIV(salophen)(OTf)2]
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In the present work, highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by high-valent [Ti IV(salophen)(OTf)2] is reported. Under these conditions, primary, secondary and tertiary alcohols as well as phenols were silylated in short reaction times and high yields. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.
- Yadegari, Maryam,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 332 - 338
(2012/03/12)
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- Highly efficient and selective trimethylsilylation of alcohols and phenols with hexamethyldisilazane catalyzed by polystyrene-bound tin(IV) porphyrin
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In the present work, investigation of the catalytic activity of tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn IV(TNH2PP)(OTf)2], supported on chloromethylated polystyrene in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane is reported. The prepared catalyst was characterized by elemental analysis, FT-IR and diffuses reflectance UV-Vis spectroscopic methods. This catalyst was used for selective trimethylsilylation of different alcohols and phenols with HMDS, with short reaction times and high yields. Also the catalyst is of high reusability and stability, in that it was recovered several times without loss of its initial activity.
- Gharaati, Shadab,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 87 - 95
(2012/05/05)
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- Electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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In the present work, the application of electron-deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Taghavi, S. Abdolmanaf
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experimental part
p. 687 - 694
(2012/01/06)
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- Partition coefficients of ketones, phenols, aliphatic and aromatic acids, and esters in n-hexane/nitromethane
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Liquid-liquid partition is used in sample preparation and in countercurrent and liquid-liquid chromatographic separations. Partition coefficients are widely used in toxicology, environmental, and analytical chemistry. The K hn determination procedure for the n-hexane/ nitromethane system was optimized and partition coefficients for 99 ketones, esters and trimethylsilyl derivatives of phenols, aliphatic and aromatic acids were determined. For 130 compounds, Khn values were predicted using mathematical relationships between Khn and other physicochemical and structural parameters. Versita Sp. z o.o.
- Kotowska, Urszula,Isidorov, Valery A.
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scheme or table
p. 813 - 824
(2012/03/27)
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- [SnIV(TPP)(BF4)2]: An efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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Tin(IV)tetraphenylporphyrinato tetrafluoroborate, [SnIV(TPP)(BF4)2], was used as an efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). High-valent [SnIV(TPP)(BF4)2] catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS-ethers were obtained in high yields and short reaction times at room temperature. While, under the same reaction conditions [SnIV(TPP)Cl2] is less efficient to catalyze these reactions. One important feature of this catalyst is its ability in the chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Gharaati, Shadab
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experimental part
p. 212 - 219
(2010/04/04)
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- Novel and highly effective method for the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS), catalyzed by I2 generated in situ using Fe(NO3)3 · 9 H 2O/NaI under heterogeneous and neutral conditions
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Structurally diverse alcohols and phenols were trimethylsilylated in a clean and efficient reaction with hexamethyldisilazane (HMDS) based on the use of I2 generated in situ from Fe(NO3)3 · 9 H2O/NaI. The reaction occurs very rapid in good-to-high yield in CH2Cl2 at room temperature, and the use of toxic and corrosive molecular I2 is avoided.
- Khazaei, Ardeshir,Rahmati, Sadegh,Rostami, Amin
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experimental part
p. 1434 - 1438
(2009/10/16)
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- P-toluenesulfonyl chloride (p-TsCl)-catalyzed trimethylsilylation of hydroxyl groups using hexamethyldisilazane and their regeneration under mild conditions: The first example for catalytic application of p-toluenesulfonyl chloride
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The first catalytic application of p-toluenesulfonyl chloride (p-TsCl) for the efficient and selective trimethylsilylation of various types of hydroxyl groups with hexamethyldisilazane (HMDS) in dichloromethane and desilylation of these compounds in water is reported. The reactions were carried out at room temperature and were found to proceed in good to excellent yields.
- Khazaei, Ardeshir,Rostami, Amin,Mantashlo, Fatemeh
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experimental part
p. 2288 - 2296
(2010/04/06)
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- Fe(HSO4)3 promoted trimethylsilylation of alcohols and phenols in solution and under solvent-free conditions
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Alcohols and phenols are efficiently converted to their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of Fe(HSO4)3 in solution and under solvent-free conditions.
- Shirini, Farhad,Zolfigol, Mohammad A.,Abri, Abdol-Reza
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- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable zirconyl triflate, [ZrO(OTf)2]
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In this paper, rapid and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane in the presence of catalytic amounts of ZrO(OTf)2 is reported. Primary, secondary and tertiary alcohols as well as phenols were efficiently converted to their corresponding TMS ethers in short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Chahardahcheric, Shahin,Tavakoli, Ziba
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p. 2041 - 2046
(2008/09/19)
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- Efficient trimethylsilylation of alcohols and phenols with HMDS in the presence of a catalytic amount of 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a safe and cheap industrial chemical
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1,3-Dibromo-5,5-dimethylhydantoin (DBDMH) is found to be an effective catalyst for trimethylsilylation various alcohols and phenols with hexamethyldisilazane (HMDS) in dichloromethane at room temperature.
- Khazaei, Ardeshir,Rostami, Amin,Mahboubifar, Marjan
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p. 483 - 487
(2008/02/11)
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- Trimethylsilylation of alcohols and phenols using KBr as an efficient and reusable catalyst
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KBr acts as an efficient and reusable catalyst for the selective and efficient trimethylsilylation of benzylic, primary and secondary aliphatic alcohols and phenols with hexamethyldisilazane. All reactions were performed at room temperature under mild and
- Shirini, Farhad,Mollarazi, Esmail
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p. 1109 - 1115
(2007/10/03)
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- Sulfuric acid supported on silica gel: An efficient catalyst for silylation of hydroxyl groups with HMDS and their convenient deprotection under non-aqueous condition
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A mild and efficient silylation of alcohols and phenols with hexamethyl-disilazane(HMDS) and convenient desilylation of the corresponding silyl ethers are achieved using a catalytic amount of H2SO4 SiO2 under non-aqueous condition. In this work chemoselective silylation of hydroxy compounds in the presence of thiols and amines is conducted.
- Lakouraj,Akbari
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p. 1165 - 1167
(2007/10/03)
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- Montmorillonite clay catalysis XI1: Protection and deprotection of hydroxyl group by formation and cleavage of trimethylsilyl ethers catalysed by catalysed by montmorillonite K-10
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An easy preparation of trimethylsilyl ethers of alcohols and phenols with 1,1,1,3,3,3-hexamethyldisilazane(HMDS) catalysed by montmorillonite K- 10 at room temperature has been carried out in excellent yields. Desilyation of trimeylsilyl ethers is catalysed by K-10 in methanol at ambient temperature in high yields.
- Zhang, Zhan-Hui,Li, Tong-Shuang,Yang, Feng,Fu, Cheng-Guang
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p. 3105 - 3114
(2007/10/03)
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- Yttrium-based Strong Lewis Acid Catalyst for Silylation of Alcohols with 1,1,1,3,3,3-Hexamethyldisilazane
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A variety of hydroxy compounds react with hexamethyldisilazane in the presence of a yttrium-based Lewis acid catalyst to afford the corresponding trimethylsilyl ethers in good to excellent yields.
- Kumar, Pradeep,Pais, Godwin C. G.,Keshavaraja
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p. 376 - 377
(2007/10/03)
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- Counterattack Reagent Bis(trimethylsilyl)acetamide in the Disilylation of Diols
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The counterattack method was applied to the disilylation of diols.Treatment of various diols with 0.3 or 1.1 equivalents of potassium hydride and 1.1 equivalents of bis(trimethylsilyl)acetamide in THF gave the corresponding disilyl ethers in good to excellent yields (60-95percent).The diols may contain other functionalities, such as amide, amine, ether, and thioether.The diols used in the disilylation were 2a-14a.The newly developed disilylation proceeded in one flask by a sequential deprotonation-silylation-deprotonation-silylation pathway.This disilylation also represents an example of a "tandem double-counterattack process".Bis(trimethylsilyl)acetamide acted as a counterattack reagent; it provided two Me3Si groups to diols and produced amides as bases.
- Hwu, Jih Ru,Anderson, Denise A.,Wang, Naelong,Buchner, Meredith M.,Gani, Paul,Tsay, Shwu-Chen
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p. 1667 - 1671
(2007/10/02)
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- Cyclic Ions in the Mass Spectra of Trimethylsilyl Derivatives of Substituted o-Dihydroxybenzenes
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The mass spectra of trimethylsilyl (TMS) ethers/methyl esters of phenolic acids containing o-dihydroxybenzene groups have base peaks at (1+) instead of the usual (1+) and (1+) that are characteristic of TMS/methyl esters of monohydroxyphenolic acids.These ions, formed by the loss of 31+88 u from the parent ion, possess a cyclic moiety as proven by substitution of deuterium atoms for hydrogen atoms in the TMS groups of the methyl esters of 3,4,5-trihydroxybenzoic (gallic), 3,4-dihydroxybenzoic (protocatechuic) and β-(3,4-dihydroxyphenyl)propenoic (caffeic) acids.Although these cyclic ions are the base peaks in TMS-derivatized o-dihydroxyphenolic acid esters, similar ions represent intense peaks but not neccessarily the base peak in other derivatized compounds such as 1,2-dihydroxybenzene, 1,2-dihydroxy-3-methyl- and 1,2-dihydroxy-4-methyl-benzenes and flavan-3-ols that possess o-dihydroxybenzene groups.Compounds possessing m- or p-dihydroxybenzene groups do not form these cyclic ions; therefore, this procedure for derivatization and interpretation of mass spectra is valuable for the identification of compounds containing o-dihydroxybenzene groups in complex mixtures of isomeric compounds.
- Horvat, Robert J.,Senter, Samuel D.
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p. 413 - 417
(2007/10/02)
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- TRIMETHYLSILYLATED N-ALKYL-SUBSTITUTED CARBAMATES. I. PREPARATION AND SOME REACTIONS
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Trimethylsilyl N-monoalkyl- and N,N-dialkyl-carbamates have been made in 85-95percent yields by silylation of the corresponding ammonium carbamates with trimethylchlorosilane.Trimethylsilyl N,N-dimethylcarbamate can be used for silylation of alcohols, phenols, and carboxylic acids.The silylcarbamates react with carboxylic acid halides to give the corresponding acid amides.The reaction of trimethylsilyl carbamates with carboxylic anhydrides give the corresponding silyl carboxylate and acid amide, while the reaction with dicarboxylic anhydrides give the trimethylsilyl monoamide of the corresponding dicarboxylic acid, i.e.Me3SiO2CCONR1R2.
- Knausz, Dezsoe,Meszticzky, Aranka,Szakacs, Laszlo,Csakvari, Bela,Ujszaszy, Kalman
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