Sanny Verma

Grafting of oxo-vanadium Schiff base on graphene nanosheets and its catalytic activity for the oxidation of alcohols

Graphene oxide was found to be a convenient and efficient supporting material for grafting of oxo-vanadium Schiff basevia covalent attachment. The low dimensionality and rich surface chemistry of graphene oxide play critical roles in order to achieve a good degree of such grafting. Catalytic potential of the so prepared graphene-bound oxo-vanadium Schiff base and comparison with its homogeneous analogue was studied for the oxidation of various alcohols to carbonyl compounds using tert-butylhydroperoxide as oxidant. The structural and chemical nature of the catalyst was characterized by a variety of techniques including XRD, FTIR, TGA, TEM, and ICP-AES. The immobilized complex was found to be highly efficient and showed comparable catalytic reactivity as its homogenous analogue with the added benefits of facile recovery and recycling of the heterogeneous catalyst. The graphene-bound oxo-vanadium Schiff base was successfully reused for several runs without significant loss in its catalytic activity.

Starch Immobilized Ruthenium Trichloride Catalyzed Oxidative Cyanation of Tertiary Amines with Hydrogen Peroxide.

Starch immobilized ruthenium trichloride, easily synthesized by the reaction of silyl functionalized imidazolium chloride and hydroxyl groups of expanded corn starch (ECS) followed by the reaction with ruthenium trichloride, was found to be a highly efficient and recyclable catalyst for the oxidative cyanation of tertiary amines to α‐aminonitriles in high yields using hydrogen peroxide with sodium cyanide in acetic acid.

PEG-embedded KBr3: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

Summary PEG-embedded potassium tribromide ([K+PEG]Br3 −) was found to be an efficient and recyclable catalyst for the synthesis of functionalized piperidines in high yields in a one step, three component coupling between aldehyde, amine and β-keto ester. At the end of the reaction the [K+PEG]Br3 − was readily regenerated from the reaction mixture by treating the residue containing [K+PEG]Br− with molecular bromine.

Immobilized oxo-vanadium Schiff base on graphene oxide as an efficient and recyclable catalyst for the epoxidation of fatty acids and esters

Oxo-vanadium Schiff base was covalently immobilized onto chemically functionalized graphene oxide (GO) using 3-aminopropyltriethoxysilane as a coupler. The loading of vanadyl Schiff base onto GO nanosheets was confirmed by FTIR, XRD, TGA, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The synthesized heterogeneous catalyst was found to be efficient and selective for the epoxidation of fatty acids and esters using t-butyl hydroperoxide (TBHP) as an oxidant. Interestingly, the immobilized catalyst showed a higher catalytic efficiency than the homogeneous vanadyl acetylacetonate. The recycling experiment results indicated that the catalyst was highly stable and maintained very high activity, and selectivity even after being used for six cycles.

Thiourea dioxide with TBHP: a fruitful and greener recipe for the catalytic oxidation of alcohols

Thiourea dioxide, owing to its hydrogen bonding ability, has been established as an exceptional, widely applicable organocatalyst. In the present paper, thiourea dioxide, an organocatalyst, in combination with t-butyl hydroperoxide (TBHP), a non-toxic and environmentally benign oxidant, serves to be a greener and more fruitful approach for the oxidation of alcohols to corresponding carbonyl compounds in excellent yields under mild reaction conditions.

Nanosized zinc peroxide (ZnO2): a novel inorganic oxidant for the oxidation of aromatic alcohols to carbonyl compounds

Zinc peroxide (ZnO2) nanoparticles were readily synthesized from the oxidation of zinc acetate with hydrogen peroxide at room temperature. The synthesized material was fully characterized by FTIR, XRD, TG-DSC, FE-SEM, TEM and XPS analysis. As obtained nanosized zinc peroxide was found to be an efficient oxidant for the oxidation of aromatic alcohols to the corresponding carbonyl compounds selectively in excellent yields using dimethyl carbonate as an environmentally benign solvent.

Amino-functionalized carbon nanofibres as an efficient metal free catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and 2-aminobenzonitriles

Carbon nanofibres (CNFs) functionalized with 4-amino-2,6-dimethylpyridine were found to be an efficient metal free catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and 2-aminobenzonitriles using water as a reaction medium. The presence of water they exhibited a remarkable enhancement in reaction rates and provided high to excellent yield of the products. After completion of the reaction, the catalyst was easily separated by centrifugation and was successfully reused for several runs without showing any significant decrease in catalytic activity.

Complexation of KBr3 with Poly (Ethylene Glycol): Efficient Bromination of Aromatics Under Solvent-less Conditions

The complexation of KBr3 with acyclic poly (ethylene glycol)-400 was carried out in which the chain of polyether suitably wrapped around the cation in a host-guest manner. The resulting complex was found to be an efficient brominating agent for the selective regioselective monobromination of various aromatic compounds in excellent yields under mild reaction conditions. In another protocol, bromination was carried out by using the PEG-embedded KBr3 as a catalyst in the presence of hydrogen peroxide. The presence of hydrogen peroxide enhanced the reaction rates and provided selective bromination within very short reaction times.

A recyclable PEG-crowned potassium tribromide [{K+PEG}·Br3−] for the synthesis of tetrabromobisphenol A

Polyethylene glycol-bound potassium tribromide [{K+PEG}·Br3−] was found to be an efficient brominating agent for the bromination of bisphenol A to tetrabromobisphenol A of a very high purity in excellent yield. The brominating agent was easily prepared by reacting the PEG400 with KBr3 using the host-guest chemistry concept. The effect of various reaction parameters such as solvent, temperature, and concentration of brominating agent on the yield and purity of tetrabromobisphenol A was studied. The key advantages of the developed method are the use of inexpensive, non-volatile poly(ethylene)glycols, facile regeneration, and inbuilt recycling of generated HBr waste.

Nanocrystalline zinc peroxide mediated unprecedented nitrene transfer: an expeditious access to N-tosylaziridines

An unprecedented zinc peroxide (ZnO2) assisted synthetic strategy is reported for the synthesis of N-tosylaziridines from alkenes by using N-tosyliminotriphenylphosphorane (Ph3PNTs) as a nitrene transfer reagent under mild reaction conditions. The reaction of zinc peroxide with Ph3PNTs yielded a zinc oxaziridine intermediate which subsequently reacts with alkenes to give corresponding N-tosylaziridines in high to excellent yields.