scholarly journals Recyclable Polymer-Supported N-Hydroxyphthalimide Catalysts for Selective Oxidation of Pullulan

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3585
Author(s):  
Madalina Elena Culica ◽  
Kornela Kasperczyk ◽  
Raluca Ioana Baron ◽  
Gabriela Biliuta ◽  
Ana Maria Macsim ◽  
...  
Keyword(s):  
Sodium Hypochlorite ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Water Soluble ◽  
Particle Charge ◽  
Oh Groups ◽  
Convenient Route ◽  
Polymer Supported ◽  
Polyelectrolyte Titration

This paper proposes a convenient route to oxidize the –CH2–OH groups in the water-soluble pullulan, using a new catalytic polymer-supported N-hydroxyphthalimide (NHPI) immobilized on polystyrene. The protocol involves the presence of sodium hypochlorite and sodium bromide. The conversion is possible at room temperature, atmospheric pressure, and pH = 10. The characterization of both the catalysts and oxidized pullulan was done using NMR and FTIR methods. Using polyelectrolyte titration with end-point indication by means of a particle-charge detector (PCD), we were able to assess the degree of electrokinetic charge in all oxidized samples as a consequence of the conversion of the –CH2–OH group into –COOH moieties. The possibility of recovery and recycling of the polymer-supported NHPI catalyst was tested for up to four cycles, since the morphological analyses performed on the catalysts using SEM revealed no significant changes.

Characterization of a ruthenium/titania catalyst for selective methanation at room temperature and atmospheric pressure

Langmuir ◽  
1991 ◽  
Vol 7 (11) ◽  
pp. 2642-2648 ◽  
Author(s):  
K. Ravindranathan. Thampi ◽  
L. Lucarelli ◽  
John. Kiwi
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature

Synthesis and structural characterization of a new heterometallicmolybdate coordination polymer based on a µ3-bridging amino alcohol

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Savita A. Kundaikar ◽  
Sudesh M. Morajkar ◽  
Wolfgang Bensch ◽  
Bikshandarkoil R. Srinivasan
Keyword(s):  
Coordination Polymer ◽  
Room Temperature ◽  
Binding Mode ◽  
Water Molecules ◽  
Inversion Center ◽  
Oh Groups ◽  
Heterometallic Coordination Polymer ◽  
Anionic Ligand ◽  
Hydrogen Bonding Interactions

Abstract The reaction of Na2MoO4·2H2O with 2-amino-2-(hydroxymethyl)propane-1,3-diol (LH) in water at room temperature results in the formation of the heterometallic coordination polymer [Mo2O6L2(Na2(H2O)4)]·2H2O 1 (L = 2-amino-3-hydroxy-2-(hydroxymethyl)propan-1-olato). The structure of 1 consists of a neutral (Mo2O6) unit located on an inversion center. The Mo atoms exhibit hexa-coordination and are bonded to two terminal and two bridging oxido ligands, an alkoxide oxygen and the amine N atoms of an anionic ligand L– resulting in the formation of an edge-sharing {Mo2O8N2} bioctahedron. The Na+ cations of a centrosymmetric bis(μ2-aqua)-bridged (Na2(H2O)4)2+ unit are penta-coordinated and bonded to two symmetry related L– ligands via the oxygen atoms of their OH groups. The µ3-bridging tetradentate binding mode of L– results in the formation of a two-dimensional heterometallic coordination polymer. The constituents of 1 viz. (Mo2O6), (L)–, (Na2(H2O)4)2+ and lattice water molecules are interlinked with the aid of three varieties of hydrogen bonding interactions. The corresponding tungstate reported recently has been obtained through a similar synthetic protocol and is isostructural.

Quadrol-Pd(II) complexes: phosphine-free precatalysts for the room-temperature Suzuki-Miyaura synthesis of nucleoside analogues in aqueous media

2022 ◽  
Author(s):  
Jose Luis Serrano ◽  
Sujeet Gaware ◽  
Jose Antonio Pérez de Haro ◽  
Jose Pérez ◽  
Pedro Lozano ◽  
...  
Keyword(s):  
Room Temperature ◽  
Aqueous Media ◽  
Water Soluble ◽  
Nucleoside Analogues ◽  
Synthesis And Characterization ◽  
First Time

Commercially available Quadrol, N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPEN), has been used for the first time as N^N- donor neutral hydrophilic ligand in the synthesis and characterization of new water soluble palladium (II) complexes...

The Effects of Particle Size, Morphology, and Mass Loading on the Reactivity of Nanocatalytic Particles

2007 ◽  
Author(s):  
Brian Fellon ◽  
Christopher Ricciuti ◽  
Yi Ma ◽  
Tiffany Miller ◽  
Howard Pearlman
Keyword(s):  
Particle Size ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Initial Temperature ◽  
Mass Loading ◽  
Oak Ridge ◽  
Portable Power ◽  
Effect Of Particle Size ◽  
Operating Temperatures

Nanocatalytic particles of Gold (Au), Platinum (Pt), and Palladium (Pd) are highly reactive at room-temperature and can be used to generate heat in micro-scale devices for portable power generation. No pre-heating is required for light-off and high steady-state operating temperatures can be sustained with high density alcohol-air premixtures. Preliminary experiments conducted in our lab and those reported by Hu and co-workers at Oak Ridge National Lab have measured peak operating temperatures ∼ 300–500 degrees Celsius using near-stoichiometric methanol/air and ethanol/air premixtures at ambient initial temperature and atmospheric pressure. The effect of particle size, morphology, mass loading, and flow residence time are reported for different mixture stoichiometries. Temperature measurements and gas species analyses are also tabulated. Interestingly, smaller particles were observed to be less reactive than larger particles for the same mass loadings for select conditions. Materials characterization of the particles has also been conducted to characterize the specific surface area of the catalyst and evaluate the importance of particle sintering, morphology changes, and particle distribution.

Dielectric behavior of a quaternary composite (RE, BT, MnO2, CaO) in the band (DC–2 GHz)

2018 ◽  
Vol 84 (1) ◽  
pp. 10201 ◽  
Author(s):  
Mounir Bouchaour ◽  
Juan Pablo Martínez Jiménez ◽  
Nacerdine Bouzit ◽  
Nacerdine Bourouba
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Volume Fraction ◽  
Low Frequency ◽  
Wide Band ◽  
Dielectric Behavior ◽  
Resin Matrix ◽  
Ternary Composite ◽  
Dielectric Characterization

The main objective of this paper is to study the dielectric behavior of a quaternary composite, made from a mixture of barium titanate (BT), manganese dioxide (MnO2) and calcium oxide (CaO) in the same epoxy resin matrix (RE) maintained at 70% by volume fraction, while those of the other constituents are variable and completing each other in a way to achieve the remaining proportion, i.e. 30%. Random mixtures are made at room temperature and under atmospheric pressure. A dielectric characterization of this mixture type was performed by time-domain spectroscopy (TDS) over a frequency wide band (DC–2 GHz). This has been carried out to illustrate the effect of two oxides (MnO2 and CaO) simultaneously at low frequency (500 MHz), in the presence of (BT), on the composite dielectric behavior. This has led consequently to make a comparison between the present acquired results and those of the ternary composite, where (MnO2) and (CaO) act separately. The results obtained so far in this study allowed us to check the validity of the modified Lichtenecker law (MLL)-based predictive model in the quaternary composite case. The interest of this study lies on applications of these materials in microelectronics circuits and absorber materials in telecommunication domain.

scholarly journals Phosphidoboratabenzene–rhodium(i) complexes as precatalysts for the hydrogenation of alkenes at room temperature and atmospheric pressure

2016 ◽  
Vol 45 (5) ◽  
pp. 2130-2137 ◽  
Author(s):  
Viridiana Perez ◽  
Pierre Audet ◽  
Wenhua Bi ◽  
Frédéric-Georges Fontaine
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Rhodium Complex ◽  
Synthesis And Characterization

The synthesis and characterization of a phosphido-boratabenzene rhodium complex is reported. The species acts as a precatalyst for the hydrogenation of alkenes at room temperature and atmospheric pressure.

scholarly journals Cyclodextrins in polymer synthesis: Dimethyl-β-cyclodextrin as thermosensitive retardant for the radical polymerization of N-methacryloyl-L-tyrosine derivatives in water

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Monir Tabatabai ◽  
Helmut Ritter ◽  
Monika Schmelzer
Keyword(s):  
Molecular Weight ◽  
Methyl Ester ◽  
Radical Polymerization ◽  
Ethyl Ester ◽  
Room Temperature ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Organic Solution ◽  
Tyrosine Derivatives

AbstractThe synthesis and characterization of N-methacryloyl-L-tyrosine methyl ester (3a) and ethyl ester (3b), and their acetyl derivatives O-acetyl-N-methacryloyl- L-tyrosine methyl ester (4a) and ethyl ester (4b) are described. Monomers 3 and 4 were complexed with RAMEB (randomly methylated ß-cyclodextrin) yielding water soluble host-guest complexes 5a-d. The radical polymerization of monomers 3 and 4 was investigated in the presence as well as in the absence of RAMEB in aqueous medium at room temperature and also at 60°C. It is shown that the polymerization tendency of complexes 5a-d at room temperature is lower, leading to polymers of higher molecular weight, compared to the free monomers 3 and 4. Furthermore, the polymerization of monomers 3 and 4 was carried out in homogenous organic solution using 2,2’-azoisobutyronitrile as initiator, and the results are discussed.

Characterization of TiC/Ni Composite Immersed in Synthetic Seawater

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2865-2873 ◽  
Author(s):  
J. M. Durán-Olvera ◽  
R. Orozco-Cruz ◽  
R. Galván-Martínez ◽  
C.A. León ◽  
A. Contreras
Keyword(s):  
Corrosion Rate ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Electrochemical Cell ◽  
Electrode Array ◽  
Corrosion Process ◽  
Corrosion Morphology ◽  
Synthetic Seawater ◽  
Static Conditions

ABSTRACTThis work shows the electrochemical study of nickel (Ni) and TiC/Ni composite immersed in synthetic seawater. In order to characterize the corrosion process, polarization curves (PC) were carried out. All electrochemical measures were made under static conditions, room temperature, atmospheric pressure and 24 hours exposure time. An electrochemical cell with a typical three-electrode array was used. Effect of TiC as reinforcement into the Ni matrix was evaluated. According PC results, it is possible to point out that the corrosion rate (CR) of the TiC/Ni composite was higher than Ni corrosion rate. The obtained results indicate that the corrosion process of both materials is of mixed type, that is to say a process of transfer of load influenced by a mechanism of mass transfer. Observations through scanning electron microscopy (SEM) revealed that mechanism of corrosion was cells of differential aeration (difference of concentration of oxygen). The corrosion morphology was localized type (pits and crevice).

A Convenient Route to α,β-Unsaturated Aldehydes Based on Polymer-Supported α-Selenoaldehydes

2003 ◽  
Vol 2003 (5) ◽  
pp. 258-259 ◽  
Author(s):  
Shou-Ri Sheng ◽  
Lu-Ling Wu ◽  
Xian Huang
Keyword(s):  
Hydrogen Peroxide ◽  
Room Temperature ◽  
Wittig Reaction ◽  
Subsequent Oxidation ◽  
Unsaturated Aldehydes ◽  
Convenient Route ◽  
Polymer Supported

Polystyrene-supported (4-phenylseleno)morpholine was synthesised and could be used as an efficient α-selenenylating agent for saturated aldehydes; subsequent oxidation of polystyrene-supported α-selenoaldehydes and the products from the Wittig reaction of them with chloromethylidenetriphenylphosphorane with an excess of 30% hydrogen peroxide at room temperature afforded α,β-unsaturated aldehydes in good yields and purities.

Selective conversion of aldehydes to carboxylic acids by hemoglobin and air

2018 ◽  
Vol 22 (08) ◽  
pp. 679-685 ◽  
Author(s):  
Mahdi Hajimohammadi ◽  
Maryam Khalaji Verjani ◽  
Hoda Ghasemi ◽  
Nasser Safari ◽  
Günther Knör
Keyword(s):  
Carboxylic Acids ◽  
Mass Spectroscopy ◽  
Room Temperature ◽  
Aqueous Media ◽  
Water Soluble ◽  
Feasible Method ◽  
Vis Spectroscopy ◽  
Major Route ◽  
High Valent

A new green, environmentally friendly and economically feasible method for the oxygenation of benzaldehyde, cinnamaldehyde, 4-chlorobenzaldehyde and 4-bromobenzaldehyde to the corresponding carboxylic acids using air in the presence of hemoglobin as a water-soluble catalyst in aqueous media at room temperature is illustrated. The resulting products were obtained with (77–100%) conversion and 100% selectivity within a reasonable amount of time. In addition, the first direct characterization of a high-valent iron intermediate (HbFe[Formula: see text]O) measured using Mass Spectroscopy (MS) and UV-vis spectroscopy proved that the major route for oxidation of aldehydes is (HbFe[Formula: see text]O) production.

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