18840-04-5Relevant academic research and scientific papers
Fe(HSO4)3 promoted trimethylsilylation of alcohols and phenols in solution and under solvent-free conditions
Shirini, Farhad,Zolfigol, Mohammad A.,Abri, Abdol-Reza
, p. 17 - 20 (2008)
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.
Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
, p. 15 - 23 (2013/01/14)
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
The effect of solvent accessible surface on Hammett-type dependencies of infinite dilution 29Si and 13C NMR shifts in ring substituted silylated phenols dissolved in chloroform and acetone
Blechta, Vratislav,Sabata, Stanislav,Sykora, Jan,Hetflejs, Jiri,Soukupova, Ludmila,Schraml, Jan
experimental part, p. 128 - 134 (2012/08/07)
Infinite dilution 29Si and 13C NMR chemical shifts were determined from concentration dependencies of the shifts in dilute chloroform and acetone solutions of para substituted O-silylated phenols, 4-R-C6H4-O-SiR′2R″ (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3), where the silyl part included groups of different sizes: dimethylsilyl (R′ = Me, R″ = H), trimethylsilyl (R′ = R″ = Me), tert-butyldimethylsilyl (R′ = Me, R″ = CMe3), and tert-butyldiphenylsilyl (R′ = C6H5, R″ = CMe3). Dependencies of silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that the substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to the solvent accessible surface of the oxygen atom in the Si-O-C link. Copyright
Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
Khaligh, Nader Ghaffari
experimental part, p. 63 - 70 (2011/12/02)
New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, 1H NMR and 13C NMR studies. All the products were extensively characterized by 1H NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
Succinimide-N-sulfonic acid: A mild, efficient, and reusable catalyst for the chemoselective trimethylsilylation of alcohols and phenols
Shirini,Khaligh, Nader Ghaffari
experimental part, p. 2156 - 2165 (2012/04/10)
Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields. Copyright Taylor & Francis Group, LLC.
Silica-bonded S-sulfonic acid as a recyclable catalyst for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS)
Niknam, Khodabakhsh,Saberi, Dariush,Molaee, Hajar,Zolfigol, Mohammad Ali
experimental part, p. 164 - 171 (2010/04/04)
Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in tert-butylmethyl ether, and used as a catalyst for the silylation of hydroxyl groups. A good range of primary, secondary alcohols
Preparation of silica supported tin chloride: As a recyclable catalyst for the silylation of hydroxyl groups with HMDS
Niknam, Khodabakhsh,Zolfigol, Mohammad Ali,Saberi, Dariush,Molaee, Hajar
experimental part, p. 1257 - 1264 (2010/08/19)
Silica-supported tin chloride [SiO2-Sn(Cl)4-n] has been prepared by mixing tin chloride with activated silica gel in toluene under refluxing conditions for one day. Arange of primary, secondary, and tertiary alcohols as well as phenolic hydroxyl groups were converted into their corresponding trimethylsilyl ethers with hexamethyldisilazane in the presence of catalytic amounts of silica-supported tin chloride at room temperature. An excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups was also observed. This catalyst could be recycled and reused fifteen times without loss of efficiency.
Reaction of hexafluorobenzene with trimethylsilyl ethers
Zhang, Y. F.,Kirchmeier, Robert L.,Shreeve, Jean'ne M.
, p. 287 - 292 (2007/10/02)
Hexafluorobenzene reacts readily with a variety of trimethylsilyl ethers ROSiMe3 (R = CF3CH2, FCH2CH2, H(CF2)nCH2 (n = 2, 4), CF3(CF2)6CH2, CF3(CF2)5CH2CH2, Me3SiOCH2CH2, C6F5OCH2CH2, C6H5, 4-FC6H4) to give from mono- to hexapolyfluoroalkoxy- and polyfluoroaryloxy-benzenes.The structure of C6(OCH2CF3)6 has been confirmed by single-crystal X-ray analysis.The perfluorinated ether C6F5OCF2CF3 may be synthesized from C6F5OCH2CF3 by chlorination and subsequent fluorination with SbF3/SbCl5.The chlorination of 5,6,7,8-tetrafluoro-1,4-benzodioxane is also discussed.
Kinetics and Thermodynamics of Phenolate Silylation and Alkylation
Ellington, Joe Carey,Arnett, E. M.
, p. 7778 - 7785 (2007/10/02)
A kinetic and thermodynamic investigation of the silylation reactions of alkali phenolates with several trisubstituted silyl chlorides was performed in tetrahydrofuran, acetonitrile, and dimethyl sulfoxide.Heats and rates of reaction were determined by titration calorimetry and stopped-flow techniques and found to be strongly dependent upon solvent polarity, ion pairing of the alkali phenolate, and steric and electronic influences.Reaction rates were considerably faster in acetonitrile and dimethyl sulfoxide than in tetrahydrofuran where ion-pairing effects were significant.Rates were accelerated by the addition of crown ethers.In most cases, potassium phenolates were more reactive than the corresponding sodium phenolates.The order of reactivity observed for the silyl chlorides increased as follows: i-Pr3 a's of the parent phenols, and the appropriate Hammett ? constants.Hammett plots for the silylation reactions of substituted potassium phenolates with triphenylsilyl fluoride gave values of ρ = 1.24 and 2.40 for the reaction in acetonitrile and dimethyl sulfoxide, respectively.
