113983-99-6Relevant articles and documents
Synthesis of well-defined yttrium-based Lewis acids by capturing a reaction intermediate and catalytic application for cycloaddition of CO2 to epoxides under atmospheric pressure
Sodpiban, Ounjit,Del Gobbo, Silvano,Barman, Samir,Aomchad, Vatcharaporn,Kidkhunthod, Pinit,Ould-Chikh, Samy,Poater, Albert,D'Elia, Valerio,Basset, Jean-Marie
, p. 6152 - 6165 (2019)
Despite widespread use of yttrium halide complexes as powerful Lewis acids in catalysis, no strategies have yet been developed to prepare well-defined heterogeneous systems. Herein, we show that by applying the methodology of surface organometallic chemistry (SOMC), a readily available intermediate of the mechanism of the cycloaddition of CO2 to epoxides catalyzed by YCl3/TBAB (TBAB: tetrabutylammonium bromide) can be grafted on silica resulting in a well-defined complex [(SiO-)YCl(-OCH(CH3)CH2Cl)]. The complex was thoroughly characterized by means of elemental analysis, FT-IR, solid state (SS) NMR, XPS and XANES techniques. The thus-prepared surface complex serves as heterogeneous Lewis acid for the cycloaddition of CO2 to several epoxides under atmospheric pressure performing as a simple but efficient and recyclable material. Remarkably, the isolated complex prepared on highly dehydroxylated silica performed as the most efficient compound. Additional catalytic studies show that the yttrium complexes prepared in this study have the potential to be employed also as versatile Lewis acid catalyst for 5-hydroxymethyl furfural (HMF) reductive etherification. DFT calculations were carried out to investigate the possible grafting pathways and the mechanistic pathways of CO2-epoxide cycloaddition catalyzed by different surface model complexes.
Role of lewis and Br?nsted acidity in metal chloride catalysis in organic media: Reductive etherification of furanics
Nguyen, Hannah,Xiao, Nicholas,Daniels, Sean,Marcella, Nicholas,Timoshenko, Janis,Frenkel, Anatoly,Vlachos, Dionisios G.
, p. 7363 - 7370 (2017)
Metal chlorides are demonstrated to behave as bifunctional acid catalysts in organic media in the one-pot reductive etherification of 5-hydroxymethylfurfural (HMF) in 2-propanol toward production of biodiesel. Two competing reaction pathways, direct etherification to 5-(isopropoxymethyl)furfural and reductive etherification to 2,5-bis-(isopropoxymethyl)furan, are proposed with the selectivity depending on the metal ion. Furfural and furfuryl alcohol are used as model compounds to investigate each pathway individually. The roles of Lewis/Br?nsted acidity of metal chlorides solution are elucidated by kinetic studies in conjunction with salt speciation using electrospray soft ionization mass spectrometer. Br?nsted acidic species, generated from alcoholysis of the metal chlorides, are the predominant catalytically active species in etherification. On the other hand, partially hydrolyzed metal cations produced by alcoholysis/hydrolysis are responsible Lewis acid centers for furfural reduction to furfuryl alcohol. Isotopic labeling experiments, in combination with GCMS and 1H NMR analysis, reveal an intermolecular hydrogen transfer from the a-C of 2-propanol to the a-C of furfural as the rate-limiting step of furfural hydrogenation.
The effect of oxide acidity on HMF etherification
Luo, Jing,Yu, Jingye,Gorte, Raymond J.,Mahmoud, Eyas,Vlachos, Dionisios G.,Smith, Michael A.
, p. 3074 - 3081 (2014)
The liquid-phase (69 bar) reaction of 5-hydroxymethylfurfural (HMF) with 2-propanol for production of furanyl ethers was studied at 413 and 453 K over a series of oxide catalysts, including γ-Al2O3, ZrO2, TiO2, Al2O3/SBA-15, ZrO 2/SBA-15, TiO2/SBA-15, H-BEA, and Sn-BEA. The acidity of each of the catalysts was first characterized for Bronsted sites using TPD-TGA of 2-propanamine and for Lewis sites using TPD-TGA of 1-propanol. Catalysts with strong Bronsted acidity (H-BEA and Al2O 3/SBA-15) formed 5-[(1-methylethoxy)methyl]furfural with high selectivities, while materials with Lewis acidity (γ-Al2O 3, ZrO2, TiO2, and Sn-BEA) or weak Bronsted acidity (ZrO2/SBA-15 and TiO2/SBA-15) were active for transfer hydrogenation from the alcohol to HMF to produce 2,5-bis(hydroxymethyl)furan, with subsequent reactions to the mono- or di-ethers. Each of the catalysts was stable under the flow-reactor conditions but the selectivities varied with the particular oxide being investigated. the Partner Organisations 2014.
