Dilip Konwar

Deprotection of oximes, imines, and azines to the corresponding carbonyls using Cu-nanoparticles on cellulose template as green reusable catalyst

The deprotection of wide varieties of oximes, imines, and azines to their corresponding carbonyls has been achieved using Cu-nanoparticles on a cellulose template as a reusable catalyst. The reactions were carried out at 80–100 °C using microwave irradiation in water under neutral condition. The catalyst can be reused for several cycles with good to excellent yield.

A green synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature

Abstract Heterogeneous Tin (IV) hydrogen phosphate nanodisks [Sn(HPO4)2.H2O] efficiently catalyzed the one-pot three component condensation of aromatic aldehydes, β-ketoesters and urea to produce 3,4–dihydropyrimidin-2-ones under solvent-free conditions at room temperature. Also, the catalyst is equally applicable for the preparation of 1,5–benzodiazepines under the same reaction conditions. The optimum load of the catalyst required is 10 mole% and reusable. Hence, the process is green.

Thermal behavior of Ricinodendron heudelotii oil polymer

In this present study, the photopolymerization of Ricinodendron heudelotii (R. heudelotii) oil have been carried out with iron(III) tris(oxalato) ferrate(III) tetrahydrate (Fe[Fe(C2O4)3]·4H2O) as photoinitiator under UV radiation of 254xa0nm at 40xa0°C in dimethyl sulfoxide. The thermal decomposition of the R. heudelotii oil polymer is studied using thermogravimetry and differential scanning calorimetry methods. The R. heudelotii oil polymer exhibits three stage decomposition patterns, and the main decomposition occurs at the temperature range 300–500xa0°C. The apparent activation energy (Ea) of the decomposition has been calculated by three non-isothermal methods of Flynn–Wall–Ozawa, Kissinger and modified Coats–Redfern. The Johnson–Mehl–Avrami (nxa0<xa01) model was found to be the appropriate reaction model for the third and main decomposition step. The model could be established as

Photopolymerization of Ricinodendron heudelotii oil and methyl methacrylate in presence and absence of iron(ΙII) oxalato complex as photoinitiator

f(alpha ) = 0.52(1 - alpha ),[- ln (1 - alpha )]^{( - 0.92)}

A simple, green and one-pot four-component synthesis of 1,4-dihydropyridines and their aromatization

f(α)=0.52(1-α)[-ln(1-α)](-0.92). The value of pre-exponential factor (A) is also determined and was found to be 4.11xa0×xa01017 min−1.

Rhodium(I) carbonyl complexes of chalcogen functionalized tripodal phosphines, [CH3C(CH2P(X)Ph2)3] {X = O, S, Se} and their reactivity

Abstract The stereoselective synthesis of 2-isoxazolidine through 1,3-dipolar cycloaddition reaction of nitrile oxide, which is in situ generation from aldoxime in the presence of N-bromosuccinamide and solid-supported reagent KF/Al2O3 at room temperature, is reported. KF/Al2O3 is sufficiently basic such that it can replace organic bases such as Et3N used in typical procedures and it catalyses the reaction to enhance the rate of the reaction. GRAPHICAL ABSTRACT

Biogenic synthesis of cellulose supported Pd(0) nanoparticles using hearth wood extract of Artocarpus lakoocha Roxb — A green, efficient and versatile catalyst for Suzuki and Heck coupling in water under microwave heating

In this work, the photopolymerization of Ricinodendron heudelotii (R. heudelotii) oil and methyl methacrylate in presence and absence of iron(III) tris(oxalato) ferrate(III) tetrahydrate (Fe[Fe(C2O4)3]·4H2O) (A) in N,N′-dimethylformamide under UV radiation of 254xa0nm at 40xa0°C has been studied. The rate of polymerization, RP, varies linearly with the inverse of [A] up to 6.5xa0×xa010−4xa0molxa0L−1 and decreases above this concentration with the increase of [A]. The photoinitiator-free polymerization and polymerization in presence of the Fe(III) photoinitiator exhibit similar polymerization behavior. Thermal analysis of poly(R. heudelotii oil-co-MMA) was investigated by thermogravimetric analysis method. The thermal analysis was performed at five different heating rates. The poly(R. heudelotii oil-co-MMA) synthesized in the presence of the photoinitiator exhibits three stages of decomposition while two stages of decomposition pattern are prominent in photoinitiator-free polymers and for both polymers the main decomposition occurs at temperature range 300–500xa0°C. The apparent activation energy (Ea) of the decomposition has been calculated by three non-isothermal methods of Flynn–Wall–Ozawa, Kissinger and modified Coats–Redfern.