Ch. Venkat Reddy

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.

Catalytic C–C Bond Formation Promoted by Mg–Al–O–t-Bu Hydrotalcite

Abstract Mg–Al–O–t-Bu-hydrotalcite catalyst was found to be an efficient, environmentally attractive and selective solid base catalyst for 1,4 Michael addition. Mg–Al–O–t-Bu hydrotalcite is also effective for simple synthesis of α,β-unsaturated esters and nitriles by condensation of the corresponding activated carboxylic esters or nitriles with various aldehydes by Knoevenagel condensation. These reactions proceeded at room temperature at a greater rate in the presence of Mg–Al–O–t-Bu hydrotalcite than in the presence of any of the other catalysts examined.

Mg–Al–O–t-Bu hydrotalcite: a new and efficient heterogeneous catalyst for transesterification

Normal and β-ketoesters have been successfully transesterified with primary, secondary, unsaturated, allylic, cyclic, hindered alcohols and amines by Mg-Al-O-t-Bu hydrotalcite catalyst for the first time affording excellent yields of products at a faster rate under heterogeneous catalysis.

Aldol and Knoevenagel condensations catalysed by modified Mg–Al hydrotalcite: a solid base as catalyst useful in synthetic organic chemistry

Aldol and Knoevenagel condensations were performed with suitably activated Mg–Al hydrotalcite as catalyst in quantitative yields in the liquid phase under mild reaction conditions at a faster rate for the first time.

Henry reactions catalysed by modified Mg–Al hydrotalcite:. an efficient reusable solid base for selective synthesis of β-nitroalkanols†

Henry reactions have been performed for the first time with suitably activated Mg–Al hydrotalcite as catalyst in quantitative yields in the liquid phase under mild reaction conditions and with low reaction times. Exclusive synthesis of β-nitroalkanols (3) is realised by the compatible basic Bronsted hydroxy sites of the modified hydrotalcite. Reusability with consistent activity and selectivity for a number of cycles is established indicating that the hydrated hydrotalcite employed here is a potentially eco-friendly catalyst which can replace soluble bases in commercial synthesis.

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.

Efficient Synthesis of Chalcones by a Solid Base Catalyst

Abstract A simple and efficient heterogeneous procedure has been developed for the synthesis of chalcones (α,β‐unsaturated ketones) by the Claisen–Schmidt condensation between arylaldehydes and ketones using Mg‐Al‐OtBu hydrotalcite (HT‐OtBu) as catalyst.Abstract A simple and efficient heterogeneous procedure has been developed for the synthesis of chalcones (α,β‐unsaturated ketones) by the Claisen–Schmidt condensation between arylaldehydes and ketones using Mg‐Al‐OtBu hydrotalcite (HT‐OtBu) as catalyst.

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.

Pressure-induced phase transitions of hydrotalcite by electrical resistivity, structural and thermal studies

Abstract We report for the first time the high-pressure electrical resistivity measurements on synthetic hydrotalcite up to 6 GPa at room temperature. Pressure dependence of the electrical resistivity of synthetic hydrotalcite reveals two pressure-induced irreversible phase transitions at about 1 and 3 GPa, respectively. The first transition was accompanied by decrease of electrical resistivity 30% at about 1.5 GPa and the second phase transformation was characterized by observing a first-order decrease of electrical resistivity (about 60%) at ∼2.5–3 GPa. The high-pressure phases were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopic, and differential thermal analysis studies on the pressure-quenched samples. The spectroscopic and structural studies on the pressure-quenched samples show that hydrotalcite transforms irreversibly to manasseite phase at about 1.5 GPa and further compression leads to pressure-induced amorphization of the manasseite phase of the sample at pressures 4–4.5 GPa. The thermal (DTA/TG) studies also confirm the different high-pressure modifications of hydrotalcite.