The synthesis and characterization of chitosan-silica sulfate nano hybrid (CSSNH) as a novel, green and highly efficient heterogeneous nano catalyst is described. The catalytic activity of this new biopolymeric nano catalyst was investigated in the ultrasonic assisted green synthesis of structurally diverse thiiranes from epoxides using thiourea in water at room temperature. CSSNH was characterized using some different microscopic and spectroscopic techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N adsorption isotherm, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The green nature, cheapness, efficiency, ease of preparation, handling and reusability of this new catalyst makes this catalyst to be useful for green industrial processes.
A green and highly efficient approach for the synthesis of 3,4-dihydropyrimidine-2(1H)-one/thione derivatives is described. In this approach, the three-component Biginelli reaction between (thio)urea, methyl acetoacetate and aldehydes under solvent-free condition in the presence of chitosan-silica sulfate nano hybrid (CSSNH) as a green and heterogeneous nano catalyst affords the corresponding products in good to excellent yields and in short reaction times. CSSNH is a cheap, eco-friendly, and non-toxic nano catalyst that could be easily prepared, handled, and reused for many reaction runs without significant loss of its activity.
Substituted imidazoles have wild applications in different area of sciences and industries. In this research, the catalytic activity of PPh 3 as a cheap and efficient organocatalyst is reported for synthesis of 2,4,5-trisubstituted imidazoles. In this method, ultrasonic assisted one-pot, three-component reaction of benzil, aldehydes, urea and PPh 3 in ethylene glycol as a green solvent at room temperature has been achieved to afford the structurally diverse 2,4,5-trisubstituted imidazoles in 80-95 %. The effect of different parameters on the reaction progress was also discussed. Utilizing ultrasonic irradiation dramatically improved the reaction in terms of yields and reaction times compared to conventional heating technique. The current protocol offers many advantages such as mild reaction conditions, short reaction time, the use of non-metallic, harmless, and cheap catalyst, ease of separation and purification, simple work-up procedure, and the reactivity to all types of aldehydes particularly the aliphatic aldehydes.
The synthesis and characterization of chitosan‐silica sulfate nano hybrid (CSSNH) as a novel and efficient heterogeneous nano catalyst involving acid‐base bifunctional activity is described. The catalytic potency and activity of this eco‐friendly catalyst was investigated in regioselective ring opening of epoxides with carboxylic acids to access structurally diverse 1,2‐diol mono‐esters in good to excellent yields. CSSNH catalyst was characterized using different microscopic and spectroscopic techniques encompassing scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N2 adsorption isotherm, and Fourier transform infrared spectroscopy. The green nature, cheapness, efficiency, ease of preparation, handling and reusability of this new catalyst makes this catalyst to be useful for green industrial processes.
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