Template Assisted Synthesis of Nanocrystalline Sulfated Titania: Active and Robust Catalyst for Regioselective Ring Opening of Epoxide with Aniline and Kinetic Modeling
Abstract:The regioselective ring opening of epoxides with aniline affording β-amino alcohols is commercially important. A variety of heterogeneous catalysts such as fuel lean sulfated zirconia (FLSZ), UDCaT-5, 20%Cs 2.5 H 0.5 PW 12 /K-10 clay, Hβ-zeolite, nanocrystalline sulfated titania (NCST), and titania were evaluated in the reaction of epichlorohydrin with aniline. A nanocrystalline sulfated titania (NCST) catalyst, the most active and selective, was prepared by the sol−gel method using poly(vinyl alcohol) (PVA) a… Show more
“…The β‐amino alcohols are versatile intermediates in agrochemical, and pharmaceutical industries and are also involved in the formation of biologically active molecules. They have been prepared via the ring‐opening of epoxides with amines by Yadav et al [103,104] . using nanocrystalline sulfated titania (NCST) with regioselectivity (Scheme 55).…”
Section: Sulfated Titania As a Catalyst In Organic Transformationsmentioning
confidence: 99%
“…[56] in the formation of biologically active molecules. They have been prepared via the ring-opening of epoxides with amines by Yadav et al [103,104] using nanocrystalline sulfated titania (NCST) with regioselectivity (Scheme 55). NCST catalytic activity was examined with Hβ-zeolite, zirconia-based catalyst (UDCaT-5), 20 % cesium-substituted dodecatungstophosphoric acid (Cs 2.5 H 0.5 PW 12 /K-10 clay), titania and fuel-lean sulfated zirconia (FLSZ).…”
Sulfated titania (TiO2‐SO42−) is a unique and versatile catalytic material which is non‐toxic, non‐corrosive, non‐pollutant and easily separable in nature. Sulfated titania can engage in various organic reactions, as it contains both Lewis acid and Bronsted acid sites. A wide number of organic reactions in the presence of sulfated titania have been reported, most of which displays excellent conversion and selectivity for the syntheses of desired products with significant applications. This review endeavors to give an overview of the research highlights solicitous with sulfated titania. Even though it is arduous to cover all the research articles in the literature, various milestones in the route towards highly functionalized sulfated titania are explored. It is hoped that this review article will trigger the attention of researchers over sulfated titania for the advancement of new eco‐compatible approaches in organic chemistry.
“…The β‐amino alcohols are versatile intermediates in agrochemical, and pharmaceutical industries and are also involved in the formation of biologically active molecules. They have been prepared via the ring‐opening of epoxides with amines by Yadav et al [103,104] . using nanocrystalline sulfated titania (NCST) with regioselectivity (Scheme 55).…”
Section: Sulfated Titania As a Catalyst In Organic Transformationsmentioning
confidence: 99%
“…[56] in the formation of biologically active molecules. They have been prepared via the ring-opening of epoxides with amines by Yadav et al [103,104] using nanocrystalline sulfated titania (NCST) with regioselectivity (Scheme 55). NCST catalytic activity was examined with Hβ-zeolite, zirconia-based catalyst (UDCaT-5), 20 % cesium-substituted dodecatungstophosphoric acid (Cs 2.5 H 0.5 PW 12 /K-10 clay), titania and fuel-lean sulfated zirconia (FLSZ).…”
Sulfated titania (TiO2‐SO42−) is a unique and versatile catalytic material which is non‐toxic, non‐corrosive, non‐pollutant and easily separable in nature. Sulfated titania can engage in various organic reactions, as it contains both Lewis acid and Bronsted acid sites. A wide number of organic reactions in the presence of sulfated titania have been reported, most of which displays excellent conversion and selectivity for the syntheses of desired products with significant applications. This review endeavors to give an overview of the research highlights solicitous with sulfated titania. Even though it is arduous to cover all the research articles in the literature, various milestones in the route towards highly functionalized sulfated titania are explored. It is hoped that this review article will trigger the attention of researchers over sulfated titania for the advancement of new eco‐compatible approaches in organic chemistry.
“…[3] The β-amino alcohols are vital intermediates in medicinal chemistry and have been widely implemented for the synthesis of various biologically active compounds. [4][5] One of the most important scaffolds of β-amino alcohol is hydroxyethylamine (HEA) [6] that has been extensively explored as synthon for the discovery of antimalarials [7][8] , anti-fungal [9] , HIV protease inhibitors [10] and anti-Alzheimer agents [11][12] etc. In literature, quite a few routes are available for synthesis of HEA that involves the nucleophilic ring opening of epoxide with amines under conventional heating or microwave irradiation.…”
<p>Nucleophilic ring opening reactions of epoxides with aromatic amines are in the forefront of the synthetic organic chemistry research to build new bioactive scaffolds. Here, a convenient, green and highly efficient regioselective ring opening of sterically hindered (2R,3S)-3-(<i>N</i>-Boc-amino)-1-oxirane-4-phenylbutane with various poorly reactive aromatic amines are accomplished under microwave irradiation in nitromethane. All the reactions effectively implemented for various aromatic amines involves reuse of nitromethane that supports its dual role as a solvent and catalyst. The corresponding new β-alcohol analogs of hydroxyethylamine (HEA) are isolated in 41-98% yields. The reactions proceed under mild conditions for a broad range of less reactive and sterically hindered aromatic amines. Proton NMR and UV-visible spectroscopic studies suggest that the nucleophilicity of amines is influenced by nitromethane, which is substantiated by the extensive computational studies. Overall, this methodology elucidates the first time use of nitromethane as a solvent for the ring opening reactions under microwave conditions involving equimolar ratio of epoxide and aromatic amine without any catalyst, facile ring opening of complex epoxide by less reactive aromatic amines, low reaction time, less energy consumption, recycling of the solvent and simple workup procedures.</p>
“…Due to their versatility and reactivity towards a large range of nucleophiles such as alcohols, amines, and thiols many bifunctional compounds of industrial relevance are synthesized. β‐Alkoxy alcohols and β‐amino alcohols are key intermediates in the synthesis of a wide range of biologically active synthetic and natural products, chiral auxiliaries for asymmetric synthesis and unnatural amino acids . β‐Alkoxy and β‐amino alcohols are synthesized by alcoholysis and aminolysis of epoxides, respectively.…”
Ionic liquids have been established as solvents and catalysts in a number of reactions due to their unique properties. In this study, we have synthesized sulfonic acid functionalized imidazolium based strongly acidic ionic liquid supported on graphene oxide (PTS−Im‐3@GO). PTS−Im‐3@GO was synthesized by grafting 1‐(4‐sulfobutyl)‐3‐(3‐propyltriethoxysilyl)imidazolium hydrogen sulfate onto graphene oxide (GO) by covalent bonds. The prepared PTS−Im‐3@GO was used for regio‐selective ring opening reaction of styrene oxide with isopropyl alcohol giving 95% conversion and 100% regio‐selectivity towards 2‐isopropoxy‐2‐phenylethan‐1‐ol at 50 °C. The activity of the said catalyst was compared with various heterogeneous catalysts such as GO, PTS−Im‐1@GO, PTS−Im‐2@GO, PTS−Im‐1, PTS−Im‐2, PTS−Im‐3, Hβ‐zeolite, and montmorillonite K‐10. Among all catalysts, PTS−Im‐3@GO showed good conversion towards the desired product. PTS−Im‐3@GO was characterized by FTIR, SEM, EDS, TGA, XRD, 29Si NMR, XPS and CHNS analysis. Systematic studies demonstrated that PTS−Im‐3@GO had excellent catalytic activity and regio‐selectivity for the alcoholysis of epoxides rendering β‐alkoxy alcohols and aminolysis of epoxide giving β‐amino alcohols in very good yields. The protocol is clean and green.
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