Vasudevan V. Namboodiri

Microwave-accelerated Suzuki cross-coupling reaction in polyethylene glycol (PEG)

Polyethylene glycol (PEG) is found to be an inexpensive and non-toxic reaction medium for the microwave-assisted Suzuki cross-coupling of arylboronic acids with aryl halides. This environmentally friendly microwave protocol offers ease of operation and enables recyclability of catalyst and synthesis of a variety of substituted biaryls employing palladium chloride as catalyst and potassium fluoride as the base.

Solvent-free preparation of ionic liquids using a household microwave oven

An efficient solventless protocol for the preparation of a wide variety of ionic liquids is described, which requires a simple exposure of admixed 1-methylimidazole and alkyl halides to microwave irradiation in open glass containers. The details of this clean process using a common household microwave oven, which exploits the newer inverter technology system for better power attenuation, are described. The characterization and thermal stability data on selected ionic liquids and their potential applications are summarized.

An expeditious solvent-free route to ionic liquids using microwaves

A microwave-assisted preparation of a series of ambient temperature ionic liquids, 1-alkyl-3-methylimidazolium (AMIM) halides, that proceeds via efficient reaction of 1-methylimidazole with alkyl halides/terminal dihalides under solvent-free conditions, is described.

Solvent-free tetrahydropyranylation (THP) of alcohols and phenols and their regeneration by catalytic aluminum chloride hexahydrate

Abstract A catalytic amount of aluminum chloride hexahydrate enables solvent-free tetrahydropyranylation (THP) of alcohols and phenols at moderate temperatures. A simple addition of methanol helps to regenerate the corresponding alcohols and phenols, thus rendering these protection and deprotection sequences as very efficient transformations at high substrate to catalyst ratios.

An improved preparation of 1,3-dialkylimidazolium tetrafluoroborate ionic liquids using microwaves

An efficient microwave protocol is described for the preparation of room temperature ionic liquids consisting of alkyl imidazolium cations bearing tetrafluoroborate as anions.

Selective oxidation of styrene to acetophenone in the presence of ionic liquidsPresented, in part, at the IUPAC CHEMRAWN XIV Conference on Green Chemistry:Toward Environmentally Benign Processes and Products, Boulder, Colorado, USA, 9–13 June 2001.

Palladium-catalyzed oxidation of styrene (Wacker reaction) in the presence of 1,3-dialkylimidazolium cation based ionic liquids is described under relatively benign conditions using hydrogen peroxide. The effects of various reaction parameters and a comparison of this approach with the corresponding reactions under pressurized conditions have been made.

Direct formation of tetrahydropyranols via catalysis in ionic liquid

Utilizing a simple homoallyl alcohol and an aldehyde in the presence of a catalytic amount of cerium triflate, the direct stereoselective formation of tetrahydropyranol derivatives in ionic liquid is reported.

Iron-catalyzed solvent-free conversion of alcohols and phenols into diphenylmethyl (DPM) ethers☆

A catalytic amount of iron salts enables the solvent-free preparation of diphenylmethyl (DPM) ethers of alcohols and phenols at moderate temperatures.

Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates and their use as catalysts in the solvent-free tetrahydropyranylation of alcohols and phenols

Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates, [CnMIM][AlCl4] and their application as recyclable catalysts for the efficient and eco-friendly protection of alcohols as tetrahydropyranyl (THP) ethers are described. The same catalyst can also be utilized for the deprotection of THP ethers.

Regeneration of three-way automobile catalysts using biodegradable metal chelating agent—S, S-ethylenediamine disuccinic acid (S, S-EDDS)

Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N(2) adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 μm) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant.