B. Bharathi

Tungstate-exchanged Mg-Al-LDH catalyst: an eco-compatible route for the oxidation of sulfides in aqueous mediumIICT Communication No: 020222

The catalytic oxidation of sulfides selectively to sulfoxides and/or sulfones is realised for the first time with heterogeneous tungstate-exchanged Mg-Al-LDH catalyst using 30% hydrogen peroxide in aqueous media at a faster rate in quantitative yields at room temperature. The heterogeneous catalyst showed higher activity (TOF) over its homogeneous analogues and other heterogeneous catalysts reported so far. The catalyst is well characterised by various instrumental techniques such as FT-IR spectroscopy, thermal analysis (TGA and DTA), powder XRD and chemical analysis. The catalyst is reused for six cycles with consistent activity and selectivity.

Epoxidations of olefins catalysed by new Mn(II) salen immobilized mesoporous materials

Covalently anchored Mn(II) salen complexes on mesoporous materials have been prepared by direct condensation of prefabricated Mn complex on the support or via ensembling step-wise salen entities on the support and subsequent complexation. The resultant anchored complexes have been compared with the immobilised Mn(II) salen complexes on mesoporous materials prepared by the process of cationic exchange of a Mn(II) salen complex for the epoxidation of styrene and cyclic olefins with different oxidizing agents such as PhIO and m-chloroperbenzoic acid. Both types of samples show comparable structures but the anchored complexes can be recycled with perbenzoic acid as oxidant.

Mn(III) salen catalyst for Knoevenagel condensation – a novel heterogeneous system

Knoevenagel condensations were catalysed by Mn(III) salen complex in quantitative yields under mild reaction conditions for the first time. The catalyst was reused for several cycles with consistent activity.

The first example of heterogeneous oxidation of secondary amines by tungstate-exchanged Mg-Al layered double hydroxides: a green protocolIICT Communication No: 020213.

Tungstate exchanged Mg-Al layered double hydroxides a as recyclable heterogenised catalyst along with H2O2 as an oxidant for the oxidation of sec-amines to nitrones is developed for the first time, Reactions proceed at a fast rate in aqueous media in a single step at room temperature in good to excellent yields. The heterogenised catalyst showed higher activity (TOF) over their homogeneous analogues and other heterogeneous catalysts reported so far. The obtained catalysts were well characterised by various instrumental techniques such as FT-IR spectroscopy, thermal analysis (TGA and DTA), powder XRD and chemical analysis. The catalyst can be reused for six cycles with consistent activity and selectivity.

Transesterification of β-keto esters catalysed by transition metal complexes in a novel heterogeneous way

Abstractβ‐keto esters have been successfully transesterified with primary, secondary, tertiary, allyl and alkynic alcohols by recyclable Mn(III) salen or vanadyl(IV) acetate catalysts realised while conducting the reaction deliberately for the first time in a novel heterogeneous media to afford good to excellent yields.

The first example of catalytic N-oxidation of tertiary amines by tungstate-exchanged Mg–Al layered double hydroxide in water: a green protocol

A green process, using a recyclable tungstate-exchanged Mg-Al layered double hydroxide (LDH-WO4(2-)) heterogenised catalyst and aqueous H2O2 oxidant in water, leads to N-oxidation of aliphatic tert-amines to amine N-oxides in quantitative yields, at a high rate at room temperature.

Ring opening of oxiranes catalyzed by Mn-Salen immobilized mesoporous materials

Abstract Mn-Salen immobilized mesoporous materials were found to be efficient solid catalysts for the nucleophilic ring opening of oxiranes with TMSN3, TMSCN and aniline.