Atanu Modak;Sujoy Rana;Ashwini K. Phukan;Debabrata Maiti; 《European journal of organic chemistry》2017,2017(28):4168-4174

A facile, efficient, and general deformylation reaction with a wide-ranging functional group compatibility has been developed with palladium acetate as a precatalyst under exogenous ligand-free conditions. The mechanistic details of the palladium-catalyzed deformylation reaction have been outlined on the basis of a combination of experimental and computational studies. The heterogeneous pathway is predominant for the deformylation, and homogeneous catalysis occurs to a lesser extent. This ligand-free catalytic cycle is proposed to undergo oxidative addition, migratory extrusion, and reductive elimination as the key steps. Kinetic studies reveal a first-order rate dependency with respect to the aldehyde. Furthermore, kinetic isotope effects, competition experiments, and Hammett studies suggest that the migratory extrusion step is the rate-determining step. For the homogeneous pathway, the experimental findings are also supported by DFT studies.  相似文献   

    

Dr. Oscar Tutusaus  Dr. Rana Mohtadi  Dr. Timothy S. Arthur  Dr. Fuminori Mizuno  Dr. Emily G. Nelson  Prof. Yulia V. Sevryugina 《Angewandte Chemie (International ed. in English)》2015,54(27):7900-7904

Unlocking the full potential of rechargeable magnesium batteries has been partially hindered by the reliance on chloride‐based complex systems. Despite the high anodic stability of these electrolytes, they are corrosive toward metallic battery components, which reduce their practical electrochemical window. Following on our new design concept involving boron cluster anions, monocarborane CB₁₁H₁₂^? produced the first halogen‐free, simple‐type Mg salt that is compatible with Mg metal and displays an oxidative stability surpassing that of ether solvents. Owing to its inertness and non‐corrosive nature, the Mg(CB₁₁H₁₂)₂/tetraglyme (MMC/G4) electrolyte system permits standardized methods of high‐voltage cathode testing that uses a typical coin cell. This achievement is a turning point in the research and development of Mg electrolytes that has deep implications on realizing practical rechargeable Mg batteries.  相似文献   

    

Nargis Jamila  Naeem Khan  Imran Khan  Amir Atlas Khan  Sadiq Noor Khan 《Natural product research》2016,30(12):1388-1397

The dichloromethane bark extract of Garcinia hombroniana yielded one new cycloartane triterpene; (22Z,24E)-3β-hydroxycycloart-14,22,24-trien-26-oic acid (1) together with five known compounds: garcihombronane G (2), garcihombronane J (3), 3β acetoxy-9α-hydroxy-17,14-friedolanostan-14,24-dien-26-oic acid (4), (22Z, 24E)-3β, 9α-dihydroxy-17,14-friedolanostan-14,22,24-trien-26-oic acid (5) and 3β, 23α-dihydroxy-17,14-friedolanostan-8,14,24-trien-26-oic acid (6). Their structures were established by the spectral techniques of NMR and ESI-MS. These compounds together with some previously isolated compounds; garcihombronane B (7), garcihombronane D (8) 2,3’,4,5’-tetrahydroxy-6-methoxybenzophenone (9), volkensiflavone (10), 4’’-O-methyll-volkensiflavone (11), volkensiflavone-7-O-glucopyranoside (12), volkensiflavone-7-O-rhamnopyranoside (13), Morelloflavone (14), 3’’-O-methyl-morelloflavone (15) and morelloflavone-7-O-glucopyranoside (16) were evaluated for cholinesterase enzymes inhibitory activities using acetylcholinesterase and butyrylcholinesterase. In these activities, compounds 1–9 showed good dual inhibition on both the enzymes while compounds 10–16 did not reasonably contribute to both the cholinesterases inhibitory effects.  相似文献   

    

A. S. Singha  Ashish Guleria  Raj K. Rana 《International Journal of Polymer Analysis and Characterization》2014,19(4):318-331

Functional materials obtained from cellulosic biofibers have gained attention due to the growing demand for them in the field of wastewater remediation. In view of the technological significance of functionalized cellulosic biofibers in wastewater treatment, the present study is a green approach to functionalized cellulosic fibers through graft copolymerization under microwave irradiation. The grafted cellulosic polymers were subsequently subjected to heavy metal ion adsorption studies in order to assess their application in wastewater remediation. The effects of pH, contact time, temperature, and metal ion concentration were studied in batchwise adsorption experiments. The Langmuir, Freundlich, and Tempkin models were used to show the adsorption isotherms. The maximum monolayer capacities, q _m. calculated using the Langmuir isotherm for Zn²⁺, Cd²⁺, and Pb²⁺ were found to be 37.79, 69.68, and 96.81 mg/g respectively. The thermodynamic parameter ΔH° and ΔG° values for metal ion adsorption on functionalized cellulosic fibers showed that adsorption process was spontaneous as well as exothermic in nature.  相似文献   

    

Maheshwar S. Thakur;Onkar S. Nayal;Arti Sharma;Rohit Rana;Neeraj Kumar;Sushil K. Maurya; 《European journal of organic chemistry》2018,2018(47):6729-6732

2-Aminoquinazolin-4-one based efficient organocatalytic eco-friendly reductive amination approach was developed for the mono N-alkylation of anilines using hydrosilane as a reducing agent. This practically easy and sustainable approach works under neat reaction conditions and utilizes non-toxic environmentally benign acetic acid as a dehydrating agent. The developed protocol have several advantages, such as broad substrate scope, wide functional group tolerance, short reaction time, and absence of metal catalyst in the reaction.  相似文献   

    

Atanu Rana;Pradip Kumar Das;Biswajit Mondal;Subal Dey;Danielle Crouthers;Abhishek Dey; 《欧洲无机化学杂志》2018,2018(32):3633-3643

Factors affecting the FeIFeI/FeIFe0 reduction potentials (E0) in a series of propane and azadithiolate bridged (µ-SRS)[Fe(CO)3]2 synthetic model complexes of diiron hydrogenases are investigated. The E0 is found to vary from 60 to 390 mV depending on the nature of the substituent (Alkyl or Aryl) on the nitrogen atom at the bridgehead of the azadithiolate. The E0 is found to shift to more negative values as the average C-O stretching vibrations ν(CO)avg of the CO ligands decreases, i.e., with increasing backbonding from the iron centers. This trend is accompanied by a linear dependence of the E0 on the σ Hammett parameter of the para substituents in a series of Arylamine bridged complexes and on the gas phase proton affinities (PA) of a series of Alkylamine bridged complexes. The unexpected dependence of E0 on the substituents on the bridgehead nitrogen is addressed by computational chemistry. Density functional theory (DFT) calculations accurately reproduce the geometric structures and the correlations between E0, ν(CO)avg, σ and PA observed in the experimental data. It is concluded that while for Alkyl-amine bridged complexes an interaction between the nitrogen lone pair with C–S σ* affects ca. 60 mV shift in the E0, the inductive and mesomeric effects of the substituents in the Aryl ring are responsible for ca. 300 mV shift in the E0 of the Aryl-amine bridged complexes.  相似文献   

    

A. M. Al-Sabagh  E. M. S. Azzam  M. R. Noor El Din 《Journal of Dispersion Science and Technology》2013,34(2):260-266

A series of ethoxylated sodium monooctyl sulfosuccinates [E(n)SMOSS] and ethoxylated sodium monolauryl sulfosuccinates [E(n)SMLSS] have different units of ethylene oxide (n = 9, 14, 23) were synthesized. The surface and thermodynamic properties of these surfactants have been compared with sodium dioctyl sulfosuccinate surfactant (SDOSS) as a commonly used surfactant. The surface tension measurements at 25, 35, 45, and 55°C were used to determine of the critical micelle concentration (CMC) and surface active properties of these surfactants. The effect of the ethylene oxide (EO) unit and the alkyl chain length on the surface properties for the prepared surfactants was studied. The results show that the ethoxylated sodium monoalkyl sulfosuccinates generally have lower values of CMC than that of sodium dioctyl sulfosuccinate. The values of surface active parameters indicate that the ethoxylated sodium monooctyl sulfosuccinates and ethoxylated sodium monolauryl sulfosuccinates surfactants have adsorption properties better than the sodium dioctyl sulfosuccinate surfactant as a resulted presence of ethylene oxide in molecules of the prepared surfactants. The thermodynamic parameters show that the (EO) unites in the chemical structure of ethoxylated sodium monoalkyl sulfosuccinate surfactants improve their micellization and adsorption properties.  相似文献   

    

A. M. Al-Sabagh  M. R. Noor El-Din  H. M. Mohamed 《Journal of Dispersion Science and Technology》2013,34(7):1079-1090

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situate between 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine with oleic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I), glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV), (V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and ¹HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil base mud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud (w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interesting rheology properties including shear-thinning behavior, yield value, viscoelastic effects, thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions strongly depended on the average size distribution of the dispersed droplets that could be varied both with the bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties of these emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration are strongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability is sensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. The results were discussed on the light the chemical structure of the primary emulsifiers and the emulsion ingredients.  相似文献   

    

A. M. Al‐Sabagh  Sabrnal H. El‐Hamouly  Ayman M. Atta  M. R. Noor El‐Din  Moataz M. Gabr 《Journal of Dispersion Science and Technology》2013,34(5):661-670

In this respect mono‐, di‐, and tri‐ sorbitol oleate esters [SMO, SDO, and STO] were prepared and then ethoxylated using ethylene oxide to obtain six sorbitol esters at different ethylene oxide content (e.o=5, 12, 15, 20, 35, and 45). They were tested as oil spill dispersants individually and in blends. From the obtained data, it was found that the blends are more effective than the corresponding individual surfactants. The maximum dispersion capability for the prepared surfactants was obtained at HLB range from 9 to 11 for the both individual surfactants and blends. The increase of total carbon number in the surfactant alkyl group leads to increase dispersion capability of the dispersant. The wide range of ethylene oxide content was used, but the maximum dispersion efficiency was obtained at ethylene oxide=20 in E(20)STO. Meanwhile, the dispersion capability increases when the interfacial tension decreases.  相似文献   

    

Aasim M  Bibi NS  Vennapusa RR  Fernandez-Lahore M 《Journal of separation science》2012,35(9):1068-1078

Protein adsorption onto hydrophobic interaction chromatography supports was studied by a surface-thermodynamics approach. To gather relevant experimental information, contact angle measurements and zeta potential determinations were performed on three different commercial adsorbent beads, Phenyl Sepharose 6 Fast Flow, Toyopearl Phenyl 650-C and Source 15 Phenyl, having soft to rigid backbone structure. Similar information was obtained for a collection of model proteins, lysozyme, bovine serum albumin (BSA), polygalacturonase, aminopeptidase, chymosin, aspartic protease, beta-galactosidase, human immunoglobulin G, and lactoferrin, were evaluated in the hydrated and in the dehydrated state. Based on the mentioned experimental data, calculations were performed to obtain the (interfacial) energy versus distance profiles of nine individual (model) proteins on (commercial) beads of three different types. All of these beads harbored the phenyl-ligand onto a matrix of differentiated chemical nature. Extended Derjaguin, Landau, Verwey, and Overbeek (DLVO) calculations were correlated with actual chromatographic behavior. Typical chromatography conditions were employed. The population of model proteins utilized in this study could be segregated into two groups, according to the minimum values observed for the resulting interaction energy pockets and the corresponding retention volumes (or times) during chromatography. Moreover, trends were also identified as a function of the type of adsorbent bead under consideration. This has revealed the influence of the physicochemical nature of the bead structure on the adsorption process and consequently, on the expected separation behavior.  相似文献