ABSTRACT
Novel spiropyrazoline-indolinones (4a-t) have been synthesized successfully in neutral deep eutectic solvents by reacting 5-Cl/Br-isatin (1a-b) with aromatic ketones (2a-b) and a variety of substituted hydrazines (3a-e) in good to excellent yields. This eco-friendly straightforward synthetic protocol discloses good functional group compatibility. The conventional synthetic approach was compared with the greener route of microwave-assisted synthesis of spiropyrazolines using ethanol. This approach utilized mild reaction conditions which furnished high yields in short reaction time employing one pot two-step multicomponent. All new compounds were structurally confirmed by detailed spectroscopic analysis and density functional theory calculations. This method provides efficient access to spiropyrazole derivatives using biodegradable and green solvent.
ABSTRACT
Cobalt, from industrial waste and nuclear laundry, possess health risk to human beings, animals and plants. Number of methods, other than adsorption, have been reported in literature for Co removal from waste water. In this research walnut shell powder after modification has been utilized for Co adsorption. First step of modification involved chemical treatment by four different organic acids for 72 h. Samples were collected at 24, 48 and 72 h. Second step involved thermal treatment of 72 h samples. Unmodified and modified particles have been analyzed by chemical methods and instruments i.e. UV spectrometer, FTIR, cyclic voltammetry (CV) and microscopic imaging. Thermally treated samples have shown augmented Co adsorption. CV analysis showed thermally treated samples with better capacitance. Particles modified by oxalic acid presented better Co adsorption. Oxalic acid treated particles activated for 72 h with thermal treatment provided maximum adsorption capacity 1327 ± 20.6 mg/g against Co(II) at pH 7, stirring 200 rpm, initial concentration 20 ml, adsorbent dosage (5 mg) and contact time 240 min at room temperature.
