Bis-amino methylation for the synthesis of spiro-fused piperidines using iron(III) trifluroacetate in aqueous micellar medium

An environmentally benign, multicomponent integrated chemical process has been developed for the synthesis of 3,5-dispirosubstituted piperidines by cyclo-condensation reaction of amines, formaldehyde, and dimedone using iron(III) trifluroacetate [Fe(F₃CCO₂)₃] Lewis acid in aqueous micellar medium at ambient temperature (25–30 °C). The heterogeneous solid acid catalyst conveniently promotes this double amino methylation reaction in which six molecules condense in one pot to form six new covalent bonds. The synthesized 3,5-dispirosubstituted piperidines have been screened for their in vitro antibacterial activity using agar well method. Many of these compounds showed satisfactory antibacterial activity as compared to standard drugs against all the bacteria tested.     

Trifluoroethanol and liquid-assisted grinding method: a green catalytic access for multicomponent synthesis

Research on Chemical Intermediates - An efficient and versatile mechanochemical route for the synthesis of chromene and isoindolo[2,1-a]quinazoline scaffolds has been developed via a simple mortar...     

High shear rate viscometry

We investigate the use of two distinct and complementary approaches in measuring the viscometric properties of low viscosity complex fluids at high shear rates up to 80,000 s^?1. Firstly, we adapt commercial controlled-stress and controlled-rate rheometers to access elevated shear rates by using parallel-plate fixtures with very small gap settings (down to 30 μm). The resulting apparent viscosities are gap dependent and systematically in error, but the data can be corrected—at least for Newtonian fluids—via a simple linear gap correction originally presented by Connelly and Greener, J. Rheol, 29(2):209–226, 1985). Secondly, we use a microfabricated rheometer-on-a-chip to measure the steady flow curve in rectangular microchannels. The Weissenberg–Rabinowitsch–Mooney analysis is used to convert measurements of the pressure-drop/flow-rate relationship into the true wall-shear rate and the corresponding rate-dependent viscosity. Microchannel measurements are presented for a range of Newtonian calibration oils, a weakly shear-thinning dilute solution of poly(ethylene oxide), a strongly shear-thinning concentrated solution of xanthan gum, and a wormlike micelle solution that exhibits shear banding at a critical stress. Excellent agreement between the two approaches is obtained for the Newtonian calibration oils, and the relative benefits of each technique are compared and contrasted by considering the physical processes and instrumental limitations that bound the operating spaces for each device.     

Deep eutectic solvent an efficient reaction medium for the synthesis of chromeno pyrazolo and indazolo phthalazine derivatives

The volatile, harmful and hazardous solvents have impact on human health, all organisms and environment. To reduce the use of hazardous volatile solvents, there is need to develop the alternative green reaction medium for organic transformations and is the main goal of green chemistry. The green solvent should be nonvolatile, nontoxic, biodegradable and biorenewable. Considering these parameters, herein, we have reported an efficient and environmentally benign green synthesis of chromeno pyrazolo and indazolo phthalazine derivatives in deep eutectic solvent. The present protocol contains excellent yield of the product, short reaction time, operation simplicity, reusability of solvent and no need of further purification.     

Brönsted acid hydrotrope combined catalysis in water: a green approach for the synthesis of indoloquinoxalines and bis-tetronic acids

The present work describes the applications of Brönsted acid hydrotrope combined catalyst (BAHC) as a mild, efficient and reusable catalyst for synthesis of indoloquinoxalines and bis-tetronic acids in water. Using BAHC, we synthesized many indoloquinoxaline derivatives from isatins and o-phenylene diamine using 10 mol% PTSA in 40% aqueous hydrotropic (NaPTS) solution at room temperature with 83–90% yields. On the other hand, the reaction of tetronic acid with the aldehydes/isatins forms bis-tetronic acids with 83–88% yields through Knoevengel condensation-Michael addition pathway in same BHAC. Moreover, the BAHC can be recycled upto 5th cycles with slight decrease in product yields. The extremely simple operational methodology, green solvent, ambient reaction conditions and high yields render this approach extremely appealing for the synthesis of different heterocyclic compounds.

     

Correction to: Brönsted acid hydrotrope combined catalysis in water: a green approach for the synthesis of indoloquinoxalines and bis-tetronic acids

Research on Chemical Intermediates - A correction to this paper has been published: https://doi.org/10.1007/s11164-021-04495-7     

Aqueous hydrotropic solution: green reaction medium for synthesis of pyridopyrimidine carbonitrile and spiro-oxindole dihydroquinazolinone derivatives

Research on Chemical Intermediates - From the green chemistry point of view, water is one of the most sustainable solvents for chemical transformations, but there are some limitations to its use as...     

Synthesis and characterization of new quaternary ammonium surfactant [C18-Dabco][Br] and its catalytic application in the synthesis of spirocarbocycles under ultrasonic condition

Research on Chemical Intermediates - A novel DABCO-based cationic surfactant [C18-Dabco][Br] has been easily synthesized by the reaction of DABCO and octadecyl bromide in acetonitrile at room...     

Efficient synthesis of chromeno[2,3-c]pyrazolyl-pyrazolol(s) in hydrotropic solution and their anti-infective potential

Research on Chemical Intermediates - We report synthesis of chromeno[2,3-c]pyrazolyl-pyrazolol(s) with anti-infective potential in aq. sodium p-toluenesulfonate (NaPTS) hydrotropic solution under...