Avinash A. Chaugule

Synthesis, characterization, and application of silica supported ionic liquid as catalyst for reductive amination of cyclohexanone with formic acid and triethyl amine as hydrogen source

A silica supported ionic liquid was synthesized and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and thermogravimetric analysis. All these techniques, especially SEM results indicated the presence of well-defined spherical particles having diameters larger than the pristine silica particles, confirming the successful immobilization of the ionic liquid. The prepared silica supported ionic liquid was used in the reductive amination of cyclohexanone under different conditions with different azeotropic mixtures of formic acid and triethyl amine as a hydrogen source. The catalyst showed efficient catalytic performance and excellent yields of N-cyclohexyl amine derivatives in the range of 58% to 84% at 30 °C. After completion of the reaction, the catalyst was easily recovered by simple filtration and reused for another five cycles without any significant impact on product yields. The obtained catalytic performance indicates that the present catalyst is green, very active, and reusable for the reductive amination of cyclohexanone.

Efficient fixation and conversion of CO2 into dimethyl carbonate catalyzed by an imidazolium containing tri-cationic ionic liquid/super base system

The synthesis route used to prepare dimethyl carbonate from CO2 and methanol is a most attractive route from a green chemistry point of view. Herein, we systematically studied binary catalyst systems for the synthesis of dimethyl carbonate from CO2 and methanol. It was found that [GLY(mim)3][NTf2]3IL/DBU, [GLY(mim)3][NTf2]3/MTBD and [GLY(mim)3][NTf2]3/TBD are effective binary catalysts for the direct synthesis of DMC without the need of a dehydration system. In particular, the [GLY(mim)3][NTf2]3 IL/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) system was found to have 37% MeOH conversion and 93% DMC selectivity under mild reaction conditions. However, the tri-imidazolium salts were compatible with DBU for effective CO2 adsorption, possibly because of the reactive C(2)–H in the imidazolium ring. Furthermore, the [GLY(mim)3][NTf2]3 IL/DBU catalytic system could be easily recovered and reused three times without any obvious loss of catalytic activity. The catalytic reactivity of [GLY(mim)3][NTf2]3 IL/DBU for the synthesis of DMC was proved by its predictable mechanism on the basis of 13C NMR spectroscopy.

Polyvinyl trisulfonate ethylamine based solid acid catalyst for the efficient glycosylation of sugars under solvent free conditions

Heterogeneous Bronsted solid acid catalysts have the potential to decrease the environmental impact related to chemical production. Herein, we have synthesized polyvinyl bound trisulfonate ethylamine chloride (PV-THEAC) and polyvinyl bound disulfonate ethylamine (PV-DSEA) as Bronsted solid acid catalysts which exhibited effective catalytic activity for acid catalyzed glycosylation reactions with sugar derivatives. In particular, 0.3 equiv. of the PV-THEAC catalyst was found to be the most efficient and a reusable catalyst for glycosylation reactions. A high density of the trisulfonic group (–OSO3H) contributed to the excellent catalytic activity during glycosylation. Moreover, glycosylation reactions with D-mannose, D-xylose and D-glucose have been studied with alcohol. Remarkable acceleration of the glycosylation reaction using a glycosyltrichloroacetimidate donor was obtained with the selective production of β-glycoside.

Design, synthesis and shape evaluation of cerium iron oxide nanorods for an epoxide opening reaction through azide addition

Uniform nanorod structured Ce1−xFexO2 has been synthesized through a simple urea hydrolysis method without any surfactant. The prepared nanorods of Ce0.75Fe0.25O2 are well clear and uniformly distributed with edge lengths of ∼200 nm and show a high surface area (86.95 m2 g−1). Moreover, the time-dependent growth mechanism for nanorods has been studied and proposed, beginning with self-aggregation and digestive ripening. Catalytic activity of the synthesized material is investigated for the synthesis of 2-azidoalcohol from epoxide opening reactions. Remarkably, Ce0.75Fe0.25O2 demonstrated excellent activity up to four use cycles without any obvious loss in yield.