ChemInform Abstract: Synthesis and Characterization of Diorganoselenium(IV) and Organotellurium(IV) Derivatives Containing Se‐S or Te‐S Bonds.

Srivastava, T. N.; Singh, Jai; Srivastava, Shalini

doi:10.1002/chin.199107189

Cited by 9 publications

(11 citation statements)

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“…It is very difficult to control the reaction because of over oxidations or side reactions under conventional severe reaction conditions [4,5]. Therefore, many protocols have been proposed for the catalytic transformation, including direct dehydrogenation [6][7][8] and oxidation in the presence of various oxidant, such as tert-butyl hydroperoxide (TBHP) [9,10], H 2 O 2 [11][12][13], NaIO 4 [14], meta-chloroperoxybenzoic acid (mCPBA) [15] and O 2 [16][17][18][19][20], et al…”

Section: Introductionmentioning

confidence: 99%

Effect of basicity on the catalytic properties of Ni-containing hydrotalcites in the aerobic oxidation of alcohol

Zhou

Tao

Pan

et al. 2016

Journal of Molecular Catalysis A: Chemical

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A series of Ni-containing hydrotalcites with different basicities have been prepared by introducing different Mg 2+ contents, and characterized by XRD, SEM, TG-DTG, ICP, FTIR, Hammett analysis, DR UV-Vis, XPS, et al. The effects of basicity on the catalytic performance in the selective aerobic oxidation of alcohols and the mechanism have been studied. The results showed that substituting Ni 2+ in the structure by Mg 2+ ions significantly increased the surface basicity of the catalysts. The surface basicity of Ni-containing hydrotalcites could accelerate the first acid-base reaction step in the oxidation and improve the catalytic activity. Varied alcohols were tested and discussed in the reaction system to verify the effect, and the results indicated that the activity of α-C-H bond is the key factor for the benzyl alcohol derivatives, while the first base-acid reaction step may be more important for aliphatic alcohols. The comparison results between the hydrotalcites and the calcined samples showed that the type of basic site have significantly influence on the catalytic activity, and only the Brønsted OH basic sites accelerate the oxidation. In addition, a probable mechanism for the reaction was postulated based on catalytic results, Hammett and a series of controlled experiments. The main factors affecting the catalytic oxidation of varied alcohols using molecular oxygen as the ultimate oxidant have been discussed, which may be helpful in designing more efficient catalyst.

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Section: Introductionmentioning

confidence: 99%

Effect of basicity on the catalytic properties of Ni-containing hydrotalcites in the aerobic oxidation of alcohol

Zhou

Tao

Pan

et al. 2016

Journal of Molecular Catalysis A: Chemical

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“…The process of sorption and /or complex formation of dissolved metals depends on the chemical activity of microbial biomass or the materials that are derived from various biological origin forms the base of biosorption technique for the removal of heavy metals 20 .Biosorption is the removal of heavy metals ,compounds or particulate material from any solution using low cost biological material like dead mass or natural materials with greater 205 degradative ability 21 .Process of biosorption is considered as metabolically passive as energy is not required in it and the amount of the pollutant that can be removed or destroyed by a sorbent depends on the kinetic equilibrium and composition of sorbents cellular surface 22 . Biosorption technique consists of two steps firstly the metals binds itself to the cell wall ( metabolism independent process) and secondly metal ions are transported through the cell membrane (metabolism dependent).…”

Section: Biosorptionmentioning

confidence: 99%

A Review on Bioremediation of Heavy Metals by Microbes

Saraswat¹,

Saraswat²,

Yadav³

2020

IJAR

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Heavy metals represent an interesting group of naturally existing inorganic micro-pollutants that are released in the environment by various phenomenon. Heavy metals are important both biologically and industrially but at high concentration in environment they have toxic effects. Metallic elements which have a density more than 5gm/cm 3 are termed as heavy metals. Heavy metals like Fe, Cd, Mn ,Hg Cr and many more are the indicators of human progress. Kennish (1992) 1 classified heavy metals as the metallic elements having atomic weights usually greater than 50. Hence in periodic table the transition elements from Vanadium (Except Sc and Ti) to the metalloid As, from Zirconium (except Y) to Antimony from Lanthanum to Polonium, the lanthanides and the actinides can be defined as heavy metals 2 .In All the major civilization past or present these heavy metals were used in one form or other. we can not imagine of any industry without these metals .Most of the toxic organic pollutants can be destroyed by combustion and can be converted into easily controllable pollutants such as CO, CO 2, SO x and NO x, but combustion has no effect on metals .Metals can not be destroyed. These heavy metals exists normally in the earth environment because of the continuous chemical and physical changes occurring due to metamorphic and igneous rocks. Similarly naturally occurring decay of plant and animal waste matter, precipitation or atmospheric accumulation of airborne particles from volcanic eruption, forest fire smoke, wind erosion and oceanic spray also contribute exposure of heavy metals in the environment 1. It has been found that in the past few years rapid industrialisation throughout the world has increased the concentration of these heavy metals in the environment. Toxic metals mobilize from Industrial activities and Fossil fuel combustion and eventually they are passed into the food chain leading to ecological and severe health problems. Table 1:-Industrial sources of some common heavy metals. Metals Industry Chromium (Cr) Lead (Pb) Mercury (Hg) Arsenic (As) Copper (Cu) Nickel(Ni) Cadmium (Cd) Zinc (Zn) Mining , chrome plating, coolants in industry ,As catalyst in tanning of leather , road runoff and making alloys. Mining, smelting, Lead batteries, electronic-waste, ceramics, bangle industry, ship building ,road runoff and in paints industry Chlor-alkali plants, fluorescent lights, fluorescent lamps ,dental amalgams ,thermometers, barometer, electrical appliances, , thermal power plants. Burning of fuel, Alloys, as dopent , arsenical pesticides ,herbicide , in electronic industry , thermal power plants and preservatives of wood Mining, electronic industry ,copper plating and smelting operations, Metal plating, smelting process,combustion of fossil fuel, electroplating, thermal power plants, battery industry, road runoff. Ni/Cd batteries, e-waste, paint sludge, incinerations and fuel combustion, road runoff. Smelting, electroplating, road runoff.

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“…This dilute phase contains isolated chains and/or small complexes of oppositelycharged chains in low, but non-negligible, concentrations. [1][2][3][4][5] Coacervates are ubiquitous in biological systems [6][7][8][9][10][11][12][13][14][15][16] and have found numerous technological applications as coatings, [17][18][19][20] encapsulants, [21][22][23][24] and responsive materials [25][26][27][28][29][30][31][32] in the food, [33][34][35] pharmaceutical, [36][37][38] and other industries. 39,40 Such a diverse array of applications became possible as a result of variations in the molecular details of the charged species (e.g., biological or synthetic macromolecules, charge-density, sequence, salt, and solvent conditions, etc.)…”

Section: Introductionmentioning

confidence: 99%

Ion Pairing and the Structure of Gel Coacervates

2020

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A scaling model for the structure of coacervates is presented for mixtures of oppositely-charged polyelectrolytes of both symmetric and asymmetric charge-densities for different degrees of electrostatic strength and levels of added salt. At low electrostatic strengths, weak coacervates, with the energy of electrostatic interactions between charges less than the thermal energy, k B T, are liquid. At higher electrostatic strengths, strong coacervates are gels with crosslinks formed by ion pairs of opposite charges bound to each other with energy higher than k B T. Charge-symmetric coacervates are formed for mixtures of oppositely-charged polyelectrolytes with equal and opposite charge-densities. While charge-symmetric weak coacervates form a semidilute polymer solution with a correlation length equal to the electrostatic blob size, charge-symmetric strong coacervates form reversible gels with a correlation length on the order of the distance between bound ion pairs. Charge-asymmetric coacervates are formed from mixtures of oppositely-charged polyelectrolytes with different charge-densities. While charge-asymmetric weak coacervates form double solutions with two correlation lengths and qualitatively different chain conformations of polycations and polyanions, charge-asymmetric strong coacervates form bottlebrush and star-like gels. Unlike liquid coacervates, for which an increase in the concentration of added salt screens electrostatic interactions, causing structural rearrangement and eventually leads to their dissolution, the salt does not affect the structure of strong coacervates until ion pairs dissociate and the gel disperses.

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ChemInform Abstract: Synthesis and Characterization of Diorganoselenium(IV) and Organotellurium(IV) Derivatives Containing Se‐S or Te‐S Bonds.

Cited by 9 publications

References 1 publication

Effect of basicity on the catalytic properties of Ni-containing hydrotalcites in the aerobic oxidation of alcohol

Effect of basicity on the catalytic properties of Ni-containing hydrotalcites in the aerobic oxidation of alcohol

A Review on Bioremediation of Heavy Metals by Microbes

Ion Pairing and the Structure of Gel Coacervates

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