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1.
Preparation of Nano Silica Supported Sodium Hydrogen Sulfate: As an Efficient Catalyst for the Trimethyl,Triethyl and t‐Butyldimethyl Silylations of Aliphatic and Aromatic Alcohols in Solution and under Solvent‐free Conditions
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Nano silica supported sodium hydrogen sulfate has been prepared by mixing NaHSO4 with activated Nano silicagel. We wish to report a new method for the synthesis of trimethyl (TMS), triethyl (TES) and t‐butyldimethyl silyl (TBS) ethers from benzylic, allylic, propargylic alcohols, phenols, naphtholes and some of phenolic drugs in the solution and under solvent‐free conditions. 相似文献
2.
A very efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t‐buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO4)3/Et3N in room temperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols. 相似文献
3.
In this paper, we show that the existence of immersions preserving given geometric structures between manifolds can be expressed in terms of a relation between suitably constructed moving coframes on the manifolds, and we show that the key steps in Cartan's method of equivalence can be extended to yield necessary conditions for the existence of such immersions. 相似文献
4.
An issue which has received widespread attention in rapidly growing field of DEA is the sensitivity of the results of analysis to perturbations in the data. 相似文献
5.
A novel and efficient method is described for the immediate oxidation of different organosulfur compounds using tetrabutylammonium peroxymonosulfate in the presence of manganese meso-tetraphenylporphyrin and imidazole. The method is highly chemoselective and the yields are excellent. 相似文献
6.
Shadpour E. Mallakpour Abdol-Reza HajipourSepideh Khoee 《European Polymer Journal》2002,38(10):2011-2016
4,4′-(Hexafluoroisopropylidene)-N,N′-bis(phthaloyl-l-leucine-p-amidobenzoic acid) (2) was prepared from the reaction of 4,4′-(hexafluoroisopropylidene)-N,N′-bis(phthaloyl-l-leucine) diacid chloride with p-aminobenzoic acid. The direct polycondensation reaction of monomer (2) with p-phenylenediamine (2a), 4,4′-diaminodiphenylsulfone (2b), 2,4-diaminotoluene (2c), 2,6-diaminopyridine (2d), m-phenylene diamine (2e), benzidine (2f), 4,4′-diaminodiphenylether (2g) and 4,4′-diaminodiphenyl methane (2h) was carried out in a medium consisting of triphenyl phosphite, N-methyl-2-pyrolidone, pyridine, and calcium chloride. The homogeneous mixture was heated at 220 °C for 1 min under nitrogen. The resulting poly(amide-imide)s (PAIs) having inherent viscosities 0.27-0.78 dl/g were obtained in high yield and are optically active and thermally stable. All of the above polymers were fully characterized by IR spectroscopy, elemental analyses and specific rotation. Some structural characterization and physical properties of this new optically active PAIs are reported. 相似文献
7.
Farhad Shirini Mohammad A. Zolfigol Abdol-Reza Abri 《Monatshefte für Chemie / Chemical Monthly》2008,139(1):17-20
Summary. 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. 相似文献
8.
Farhad Shirini Mohammad A. Zolfigol Abdol-Reza Abri 《中国化学快报》2008,19(1):51-54
Fe(NO3)3-9H2O/Fe(HSO4)3 was used as an efficient reagent system for the oxidation of alcohols to their corresponding carbonyl compounds. All reactions were performed in the absence of solvent in good to high yields. Under the same reaction conditions, thiols and sulfides were also converted to their corresponding disulfides and sulfoxides, respectively. 2007 Farhad Shirini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. 相似文献
9.
Abdol-Reza Mansouri 《Comptes Rendus Mathematique》2004,339(1):39-42
In this Note, we show that contrary to the dimension 3 case, isotropic contact sub-Riemannian manifolds of dimension greater than 3 do not exist. To cite this article: A.-R. Mansouri, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
10.