Praveen K. Khatri

Magnetic silica beads functionalized with cobalt phthalocyanine for the oxidation of mercaptans in an alkali free aqueous medium

Novel magnetic silica beads functionalized cobalt phthalocyanine catalyst was prepared by immobilization of the sulfonated Co(II) phthalocyanine (CoPcS) on the amino functionalized silica coated magnetic nanoparticles (Fe3O4@SiO2, SMNP) via a sulfonamide linkage. The developed catalyst was characterized by various techniques such as XRD, N2 adsorption–desorption, UV-Vis, FTIR, SEM and TGA analyses. The synthesized catalyst was found to be effective in oxidation of mercaptans in an aqueous medium by using molecular oxygen as oxidant under alkali free conditions. The efficient recovery by using an external magnet along with reusability of the catalyst in an alkali free reaction condition makes this methodology a facile, clean, effective and economically feasible approach for the oxidation of mercaptans to disulfides.

Nafion supported molybdenum oxychloride: Recyclable catalyst for one-pot synthesis of nitrones via direct condensation/oxidation of primary amines and aldehydes using UHP as oxidant

Immobilization of molybdenum(VI) oxychloride to the surface of perfluorinated ion-exchange polymer “Nafion”via an ion exchange method was carried out for the first time. The prepared Nafion immobilized molybdenum(VI) oxychloride catalyst was used for the direct synthesis of nitrones via one-pot condensation/oxidation of primary amines with aldehydes using solid urea-hydrogen peroxide (UHP) as oxidant under very mild reaction conditions. The developed polymer immobilized catalyst showed better activity than its analogous homogeneous catalyst with the added benefits of facile recovery and recyclability of the catalyst without leaching and loss in catalytic activity.

Halogen-free ammonium–organoborate ionic liquids as lubricating additives: the effect of alkyl chain lengths on the tribological performance

Novel halogen and phosphorus free ionic liquids containing chelated organoborate anions having different alkyl chain lengths and tetrabutyl ammonium cations have been studied as anti-wear and friction reducing agents under elasto-hydrodynamic/mixed lubrication conditions for steel–steel contacts. The synthesized ionic liquids were found to be quite stable at room temperature and showed a remarkable improvement in the friction-reducing and anti-wear properties of the PEG 200 lube base. The effect of alkyl chain lengths on the tribo-performance of the synthesized additives was systematically studied.

Multiple Oxo-Vanadium Schiff Base Containing Cyclotriphosphazene as a Robust Heterogeneous Catalyst for Regioselective Oxidation of Naphthols and Phenols to Quinones

Grafting of multiple oxo-vanadium Schiff base moieties to cyclotriphosphazene provided an efficient and recyclable heterogeneous catalyst for the regioselective oxidation of naphthols and phenols to quinones by using t-butylhydroperoxide as oxidant. One of the main advantages of the developed catalyst was the presence of multiple oxo-vanadium moieties in close proximity which made the developed catalyst more active as compared to its homogeneous oxo-vanadium Schiff base. After the reaction, the catalyst was easily recovered from the reaction mixture by simple filtration and reused for five runs without loss in activity.Graphical Abstract

Industrial resin “INDION 130” modified with vanadyl cations as highly efficient heterogeneous catalyst for epoxidation of fatty compounds with TBHP as oxidant

Industrial grade cation-exchange resin “INDION 130” was modified with vanadyl cations by an ion-exchange method and then used for the epoxidation of unsaturated fatty materials including acids, esters and vegetable oils using tert-butyl hydroperoxide (TBHP) in decane as oxidant. The effect of oxidant/double bond ratio, catalyst concentration, recycling of the catalyst and temperature on the conversion to epoxides was studied. After the epoxidation, the catalyst could easily be recovered by filtration and successfully reused for at least seven runs without any loss in catalytic activity.

Polymer impregnated sulfonated carbon composite solid acid catalyst for alkylation of phenol with methyl-tert-butyl ether

A polymer impregnated sulfonated carbon composite solid acid (P–C–SO3H) catalyst was synthesized via sulfonation of a composite material formed through incomplete carbonization of hydrolyzed glucose supported on a polymer matrix (co-polymer of styrene and chloromethylstyrene i.e. Merrifields peptide resin) and used for the alkylation of phenol using methyl-tert-butyl ether (MTBE) as an alkylating agent in a pressure reactor under autogenous pressure. The developed catalyst exhibited excellent catalytic activity and provided para-tert-butyl phenol (PTBP) exclusively with the added benefits of facile recovery and reusability for several runs without loss of catalytic activity.

Synthesis and tribological behavior of fatty acid constituted tetramethylguanidinium (TMG) ionic liquids for a steel/steel contact

In the present study a number of fatty acid constituted ionic liquids having tetramethylguanidinium ion as a cationic counterpart were synthesized by neutralization of 1,1,3,3‑tetramethyguanidine (TMG) with fatty acids having varying degree of alkyl chain and olefinic bonds. The structure of the synthesized ionic liquids was thoroughly characterized using a number of analytical tools such as TGA, FT-IR, 1H and 13C NMR spectroscopy. The tribo-properties of the obtained ionic liquids as high performance anti-friction and wear reducing additives were studied in different dosage to mineral base oil under condition of mixed/boundary lubrication. It was found that the anti-wear and friction reduction properties of blends were improved with increasing the alkyl chain in constituted fatty acid ionic liquids.