Priti Sharma

A photoactive catalyst Ru–g-C3N4 for hydrogen transfer reaction of aldehydes and ketones

A novel heterogeneous photoactive catalyst is developed by incorporating ruthenium over a new photoactive graphite carbon nitride (g-C3N4) support for efficient photocatalytic transfer hydrogenation of various carbonyl functional group compounds with different alcohols. A synthesized photoactive catalyst Ru–g-C3N4 exhibits good to excellent reactivity with a high turnover number (TON) under mild reaction conditions and under visible light. The physicochemical properties of the photocatalyst were analyzed by XRD, BET analysis, TGA, FT-IR, XPS, UV-visible, ICP-OES, TEM and SEM characterization techniques. The main significant features of the photoactive catalyst Ru–g-C3N4 are viz., it is easy to handle in visible light (LED lamp), does not require an external base, solvent free, non-toxic, environmentally friendly and proceeds under very mild reaction conditions. Furthermore, the solid photocatalyst Ru–g-C3N4 can be recycled efficiently and reused many times, without a major loss in reactivity.

Highly active g-C3N4 as a solid base catalyst for knoevenagel condensation reaction under phase transfer conditions

In a promising approach, heterogeneous g-C3N4 as a solid base catalyst exhibits appreciable activity in Knoevenagel condensations at room temperature for the synthesis of substituted stilbene in presence of a crown-ether phase transfer catalyst. High yield of the product substituted stilbene were isolated in a very short reaction time period (∼30 min). The solid base g-C3N4 catalyst was proven to be recyclable for several runs. Various aromatic substrates were screened using heterogeneous base g-C3N4 catalyst, exhibiting appreciable corresponding product yield (∼99%) at room temperature.

Synthesis of heterogeneous Ru(II)-1,2,3-triazole catalyst supported over SBA-15: application to the hydrogen transfer reaction and unusual highly selective 1,4-disubstituted triazole formation via multicomponent click reaction

In the present study, we demonstrate a simple and efficient method for ligand formation and covalent anchoring to a heterogeneous support via click reaction. The complex tris(triphenylphosphine)ruthenium(II) dichloride [RuCl2(PPh3)3] anchored over the click modified ligand of SBA-15 forms a new highly efficient heterogeneous SBA-15-Tz-Ru(II)TPP catalyst. Solid state 13C, 29Si, and 31P CP-MAS NMR spectra provide evidence for the formation of the heterogeneous catalyst. SBA-15-Tz-Ru(II)TPP catalyst was screened for the multicomponent click cycloaddition reaction in water medium as a green solvent and it exhibited unusual and excellent selectivity for the formation of 1,4-disubstituted triazole product under mild reaction condition. In addition, SBA-15-Tz-Ru(II)TPP catalyst also catalyzed the hydrogen transfer reaction of various carbonyl compounds with excellent catalytic activity to give the corresponding alcohols. The heterogeneous catalyst can be recycled and reused several times (five) without a loss in reactivity.

Facile continuous process for gas phase halogen exchange over supported alkyl phosphonium salts

Chloride–bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.