scholarly journals Low Temperature Chemoselective Hydrogenation of Aldehydes over a Magnetic Pd Catalyst

2019 ◽  
Vol 9 (9) ◽  
pp. 1792
Author(s):  
Liu ◽  
Wang ◽  
Gao ◽  
Wang ◽  
Cheng ◽  
...  
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Heterogeneous Catalysts ◽  
Aromatic Aldehydes ◽  
Pd Catalyst ◽  
Primary Alcohols ◽  
Mild Conditions ◽  
Excellent Yield ◽  
Chemoselective Hydrogenation ◽  
Supported Palladium

Chemoselective hydrogenation of aldehydes with heterogeneous catalysts under mild conditions is of great importance but remains a major challenge. Herein, an efficient strategy was developed for low temperature chemoselective hydrogenation of aldehydes with broad substrate scope over a magnetic material supported palladium catalyst (γ-Fe2O3@HAP-Pd). Aldehydes bearing various reducible functional groups readily underwent hydrogenation to give the corresponding primary alcohols with moderate to excellent yield at room temperature in aqueous solutions. The Hammett equation revealed that the hydrogenation of aromatic aldehydes proceeded via an anionic intermediate. Additionally, when the temperature increased to 70 °C, toluene was obtained by the deoxygenation of benzaldehyde in excellent yield. Furthermore, the γ-Fe2O3@HAP-Pd could be recycled up to six times without loss of activity and metal leaching.

Synthesis of 1,1-diacetates from Aromatic Aldehydes using Cerium(IV) Sulfate Tetrahydrate as Catalyst under Solvent-free Conditions

2005 ◽  
Vol 2005 (3) ◽  
pp. 171-172 ◽  
Author(s):  
Min Zhang ◽  
Yi-Qun Li
Keyword(s):  
Room Temperature ◽  
Aromatic Aldehydes ◽  
Solvent Free ◽  
Excellent Yield ◽  
Solvent Free Conditions

Aromatic aldehydes can be converted into the corresponding 1,1-diacetates rapidly in the presence of catalytic amounts of Ce(SO4)2·4H2O at room temperature in excellent yield under solvent-free conditions. The catalyst can easily be recovered and reused at least 4 times.

Tuning the chemoselective hydrogenation of aromatic ketones, aromatic aldehydes and quinolines catalyzed by phosphine functionalized ionic liquid stabilized ruthenium nanoparticles

2015 ◽  
Vol 5 (7) ◽  
pp. 3728-3734 ◽  
Author(s):  
He-yan Jiang ◽  
Xu-xu Zheng
Keyword(s):  
Ionic Liquid ◽  
Aromatic Aldehydes ◽  
Ruthenium Nanoparticles ◽  
Aromatic Ketones ◽  
Functionalized Ionic Liquid ◽  
Mild Conditions ◽  
Chemoselective Hydrogenation

Aromatic ketones, aromatic aldehydes and quinolines can be hydrogenated with switchable excellent chemoselectivity under mild conditions catalyzed by ruthenium nanoparticles.

A Fortuitous, Mild Catalytic Carbon–Carbon Bond Hydrogenolysis by a Phosphine-Free Catalyst

2016 ◽  
Vol 69 (5) ◽  
pp. 561 ◽  
Author(s):  
Loorthuraja Rasu ◽  
Ben Rennie ◽  
Mark Miskolzie ◽  
Steven H. Bergens
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Nmr Studies ◽  
Carbon Bond ◽  
Mild Conditions ◽  
Carbon Carbon Bond ◽  
Diamine Ligands ◽  
Insight Into

The putative catalyst trans-[Ru((S,S)-skewphos)(H)2((R,R)-dpen)] (skewphos = 2,4-bis(diphenylphosphino)pentane; dpen = 1,2-diphenylethylenediamine) transforms the trifluoroacetyl amide 2,2,2-trifluoro-1-(piperidin-1-yl)ethanone under mild conditions (4 atm H2, room temperature, 4–24 h, 1 mol-% Ru, 15 mol-% KOtBu in tetrahydrofuran) to generate the formylated amine 1-formylpiperidine and fluoroform via C–C bond hydrogenolysis. Catalysts are also prepared by reacting cis-[Ru(η3-C3H5)(MeCN)2(COD)]BF4 (COD = 1,5-cyclooctadiene) with diamine ligands in situ. Low-temperature NMR studies provided insight into this reaction.

Eco-Friendly Synthesis of 2-Substituted Benzimidazoles Using Air as the Oxidant

2013 ◽  
Vol 66 (2) ◽  
pp. 262 ◽  
Author(s):  
Guo-Feng Chen ◽  
Hai-Dong Shen ◽  
Hui-Ming Jia ◽  
Li-Yan Zhang ◽  
Hong-Yan Kang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Environmentally Friendly ◽  
Aromatic Aldehydes ◽  
Absolute Ethanol ◽  
One Pot ◽  
Mild Conditions ◽  
One Pot Condensation ◽  
The One

A simple, environmentally friendly procedure for the synthesis of 2-substituted benzimidazoles by the one-pot condensation of o-phenylenediamines with aromatic aldehydes using continuous bubbling of air in absolute ethanol at room temperature is described. The simplicity of the system, mild conditions, involvement of a non-toxic and practically inexhaustible oxidant, easy and quick isolation of the products, and moderate to good yields are the main advantages of this procedure.

Direct Synthesis of β,γ-Unsaturated α-Keto Esters from Aldehydes and Pyruvates

Synlett ◽  
2019 ◽  
Vol 30 (07) ◽  
pp. 809-812 ◽  
Author(s):  
John Mansaray ◽  
Jiarui Sun ◽  
Shisheng Huang ◽  
Weijun Yao
Keyword(s):  
Direct Synthesis ◽  
Aromatic Aldehydes ◽  
Aliphatic Aldehydes ◽  
Keto Esters ◽  
Mild Conditions ◽  
Excellent Yield ◽  
Moderate Yield

Herein, we describe two practical methods to synthesize β,γ-unsaturated α-keto esters directly from aldehydes and pyruvates promoted by BF3•Et2O in the presence of Ac2O or by Ti(OEt)4 under mild conditions. A variety of aromatic aldehydes was tolerated to afford the desired products in moderate to excellent yield. Moreover, aliphatic aldehydes and Isatin were also employed to give the γ-alkyl β,γ-unsaturated α-keto esters in moderate yield with use of the Ti(OEt)4 system.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

SuFEx Activation with Ca(NTf2)2: A Unified Strategy to Access Sulfamides, Sulfamates and Sulfonamides from S(VI) Fluorides

2020 ◽  
Author(s):  
Subham Mahapatra ◽  
Cristian P. Woroch ◽  
Todd W. Butler ◽  
Sabrina N. Carneiro ◽  
Sabrina C. Kwan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Medicinal Chemistry ◽  
Mild Conditions ◽  
Broad Array

<p><br></p> <p>A method to activate sulfamoyl fluorides, fluorosulfates, and sulfonyl fluorides with calcium triflimide, and DABCO for SuFEx with amines is described. The reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions. Additionally, we highlight the application of this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds. </p>

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