Selective Catalysis for the Reductive Amination of Furfural Towards Furfurylamine by the Graphene-Co-Shelled Cobalt Nanoparticles

<p>Amines with functional groups are widely used in the manufacture of pharmaceuticals, agricultural chemicals, polymers, and surfactants; so far, amines are mostly produced via petrochemical routes, which <a></a><a>motivates the sustainable production of amines from renewable resources</a>, such as biomass. Unfortunately, the reductive amination of biomass-derived platforms is now suffering from challenges, e.g. poor <a></a><a>selectivity </a>and carbon balances, because of the restriction of homogenous catalyst. For this reason, we developed an eco-friendly, simplified, and highly effective procedure for the preparation of non-toxic heterogeneous catalyst based on the earth-abundant metals (i.e., cobalt), whose catalytic activity on furfural or other biomass-derived platforms were proved to be broadly available. The corresponding conversion rate and few of side products were also determined so as to optimized the reaction conditions, suggesting that the prepared cobalt-supported catalyst enables easy substitution of –NH₂moiety towards functionalized and structurally diverse molecules, even under very mild industrially viable and scalable conditions. More surprisingly, the cobalt-supported catalyst could also be expediently recycled by magnetic bar and still remained the excellent catalytic activity after reusing up to eight times; on another hands, the gram-scale reductive amination catalyzed by the same catalyst exhibited the similar yield of target products in comparison to its smaller scale, which was comparable to the reported heterogeneous noble-based catalysts. And also, results from a series of analytic technologies involving XRD, XPS, TEM/Mapping and <i>in-suit</i> FTIR revealed that the structural features of catalyst are closely in relation to its catalytic mechanisms; in simple terms, <a></a><a>the outer graphitic shell is activated by the electronic interaction between the inner </a><a></a><a>metallic </a>nanoparticles and the carbon layer as well as the induced charge redistribution. In conclusion, this newly developed catalysts enable the synthesis of amines from biomass-derived platforms with satisfied selectivity and carbon balance, providing a cost-effective and sustainable access to the widely application of reductive amination.</p>

Selective Catalysis for the Reductive Amination of Furfural Towards Furfurylamine by the Graphene-Co-Shelled Cobalt Nanoparticles

<p>Amines with functional groups are widely used in the manufacture of pharmaceuticals, agricultural chemicals, polymers, and surfactants; so far, amines are mostly produced via petrochemical routes, which <a></a><a>motivates the sustainable production of amines from renewable resources</a>, such as biomass. Unfortunately, the reductive amination of biomass-derived platforms is now suffering from challenges, e.g. poor <a></a><a>selectivity </a>and carbon balances, because of the restriction of homogenous catalyst. For this reason, we developed an eco-friendly, simplified, and highly effective procedure for the preparation of non-toxic heterogeneous catalyst based on the earth-abundant metals (i.e., cobalt), whose catalytic activity on furfural or other biomass-derived platforms were proved to be broadly available. The corresponding conversion rate and few of side products were also determined so as to optimized the reaction conditions, suggesting that the prepared cobalt-supported catalyst enables easy substitution of –NH₂moiety towards functionalized and structurally diverse molecules, even under very mild industrially viable and scalable conditions. More surprisingly, the cobalt-supported catalyst could also be expediently recycled by magnetic bar and still remained the excellent catalytic activity after reusing up to eight times; on another hands, the gram-scale reductive amination catalyzed by the same catalyst exhibited the similar yield of target products in comparison to its smaller scale, which was comparable to the reported heterogeneous noble-based catalysts. And also, results from a series of analytic technologies involving XRD, XPS, TEM/Mapping and <i>in-suit</i> FTIR revealed that the structural features of catalyst are closely in relation to its catalytic mechanisms; in simple terms, <a></a><a>the outer graphitic shell is activated by the electronic interaction between the inner </a><a></a><a>metallic </a>nanoparticles and the carbon layer as well as the induced charge redistribution. In conclusion, this newly developed catalysts enable the synthesis of amines from biomass-derived platforms with satisfied selectivity and carbon balance, providing a cost-effective and sustainable access to the widely application of reductive amination.</p>

Synthesis, X-ray characterization and catalytic homogenous alcohol oxidation activity of Co(II)–carboxamide complex with green oxidant (H2O2) under mild conditions

In this study, a new air and moisture stable mononuclear cobalt(II)–carboxamide complex, [Co(TCrbx)2(CH3OH)2](ClO4)2, was synthesized and characterized (TCrbx = N-(4-methylpyridin-2-yl)thiophene-2-carboxamide). Complex characterization mainly was done with single crystal X-ray analysis. Ligand characterization was done with several spectroscopic techniques (Elemental Analysis, FT-IR, 1H NMR, 13C NMR). Cobalt(II) complex possesses distorted octahedral geometry coordinated with two carboxamide ligands at equatorial and two methanol ligands at axial positions and two perchlorate anions as counter ions. Synthesized complex was successfully tested as homogenous catalyst for the oxidation of benzyl alcohol with environmental friendly oxidant hydrogen peroxide (H2O2) under mild conditions. Benzaldehyde was selectively obtained with the conversion value of 99.5% in dimethyl formamide after 3-h reaction time at 50 °C with 133 TON value. Solvent and temperature effects were also investigated.

Kinetic and Thermodynamic Study of Oxidative Decolourisation of a Typical Food Dye (Tartrazine) in an Aqueous Environment

The study was carried out to describe the kinetics and thermodynamics of hydrogen peroxide oxidation of a typical food dye (Tartrazine). The effect of different operational factors were investigated spectrophotometricallyat wavelength460 nm under pseudo first order reaction.These included concentration of the oxidant and the dye, the pH, ionic strength and temperature of the reacting medium and the presence of transition metal ion as homogenous catalyst. A complete and smooth decolourisation was observed. The results showed that the rate of oxidation of dye increased with increasing in concentration of substrate and oxidant. Increasing in temperature, ionic strength and pH of the basic reaction medium also raised the reaction rate. The rate of oxidation also increased with increasing in the concentration of Fe (III) ion. Pseudo second order rate constant (k2) obtained was 1.95 x 10-3 M-1s-1 and 3.8 x10-3M-1s-1 in the absence and presence of Fe (III) ion respectively. The Arrhenius activation energy for the oxidation in the absence and presence of Fe (III) ion were 47.23 kJmol-1 and 42kJmol-1 respectively. Other thermodynamic parameters showed entropy of activation (ΔS#), free energy of activation (ΔG#) and Enthalpy of activation of the reaction (ΔH#) in the presence of Fe (III) as -34.7 JK-1mol-1, 48.4 kJmol-1 and 40.30 kJmol-1 respectively. The results in the absence of Fe (III) ion were -24.6 JK-1mol-1, 51.2 kJmol-1 and 44.0 kJmol-1respectively. The relative lower activation energy (Ea),fairly higher negative value of (ΔS#) and higher (ΔG#) , with higher rate constant in the presence of Fe(III) ion showed Fe(III) ion enhancement of rate of decolourisation. Keywords: Tartrazine Food dye, Kinetics, Thermodynamics, Hydrogen Peroxidede colourisation,

Optimization and Mathematical Modeling of Biodiesel Production using Homogenous Catalyst from Waste Cooking Oil

In the present investigation, the transesterification of waste cooking oil (WCO) to biodiesel over homogenous catalyst KOH have been carried out. To optimize the transesterification process variables both response surface method (RSM) and artificial neural network (ANN) mathematical models were applied to study the impact of process variables temperature, catalyst loading, methanol to oil ratio and the reaction time on biodiesel yield. The experiments were planned with a central composite design matrix using 24 factorial designs. A performance validation assessment was conducted between RSM and ANN. ANN models showed a high precision prediction competence in terms of coefficient of determination (R2 = 0.9995), Root Mean Square Error (RMSE = 0.5702), Standard Predicted Deviation (SEP = 0.0133), Absolute Average Deviation (AAD = 0.0115) compared to RSM model. The concentration of catalyst load was identified as the most significant factor for the base catalyzed transesterification. Under optimum conditions, the maximum biodiesel yield of 88.3% was determined by the artificial neural network model at 60 ºC, 1.05 g catalyst load, 7:1 methanol to oil ratio and 90 min transesterification reaction time. The biodiesel was analyzed by GCMS and it showed the presence of hexadecanoic acid, 9- octadecenoic acid, 9, 12, 15-octadecatrienoic acid, eicosenoic acid, methyl 18-methyl-nonadecanoate, docosanoic acid, and tetracosanoic acid as key fatty acid methyl esters.