[H2-Cryptand 222]2+(Br3 –)2 as a Tribromide-Type Catalyst for the Trimethylsilylation/Tetrahydropyranylation of Alcohols

A stable organic tribromide, [H2-cryptand 222]2+(Br3–)2 was utilized as an active catalyst for the trimethylsilylation/tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols.Keywords: [H2-cryptand 222]2+(Br3–)2, trimethylsilylation, tetrahydropyranylation, alcohols, tribromide, TMS-ether, THP-ethe

Nano-Fe3O4/O2: Green, Magnetic and Reusable Catalytic System for the Synthesis of Benzimidazoles

Magnetic nano-Fe3O4 was applied in the presence of atmospheric air as a green, efficient, heterogeneous and reusable catalytic system for the synthesis of benzimidazoles via the reactions of o-phenylenediamine (1 eq) with aryl aldehydes (1 eq) in excellentyields (85–97 %) and short reaction times (30–100 min) with a proposed mechanism.Keywords: Benzimidazole, benzene-1,2-diamine, aldehyde, nano-Fe3O4, heterogeneous catalyst, magnetite, O

Sulfonic acid functionalized imidazolium salts/ FeCl3 as novel and highly efficient catalytic systems for the synthesis of benzimidazoles at room temperature

AbstractIonic liquid 3-methyl-1-sulfonic acid imidazolium chloride/ FeCl3, as well as ionic liquid 1, 3-disulfonic acid imidazolium chloride/ FeCl3 catalytic systems, efficiently catalyzes the condensation of benzene-1, 2-diamine with aromatic aldehydes in the presence of atmospheric air as a green oxidant in ethyl acetate at room temperature to afford benzimidazole derivatives in high yields and in short reaction times. The reaction is also efficiently performed when carboxylic acids are used instead of aldehydes

Shed-Snakeskin valorisation into highly porous Co-containing nanocomposites for sustainable aqueous C–C bond formation reactions

A novel highly ordered network based on shed snakeskin has been employed as a sustainable/natural template, to fabricate efficient heterogeneous cobalt composite as catalyst by a nano-casting process. Characterization of the Cobalt nano-catalyst was investigated by several analysis methods including TEM, FESEM-EDS mapping, XRD, XPS, TGA, ICP, Raman, ATR, and N2 sorption and results verified the preparation of a nano-catalyst with highly ordered perforated structure, uniform pore size distribution, high surface area, and high stability. The nano-cobalt particles were uniformly disposed on the support with a particle size of about 100 nm, validated by various analysis methods. The catalytic performance of the synthesized catalyst was evaluated in the Suzuki-Miyaura reaction for Csp2–Csp2 bond formation in high yields (up to 97%) and excellent reactivity. The catalyst could also be recycled for at least 10 reaction runs without almost losing its activity (less than 10% after 10 runs). © 202

General approach for electrochemical functionalization of glassy carbon surface by in situ generation of diazonium ion under acidic and non-acidic condition with a cascade protocol

Immobilization of catechol derivatives on GC electrode surfaces can be performed by in situ generation and reduction of nitrocatechol. We present the oxidative nitration of catechol in the presence of nitrous acid followed by electrochemically reduction of the generated nitro aromatic group to the corresponding amine group and its conversion to diazonium cation at the electrode surface to yield a surface covalently modified with catechol. In this manner, some derivatives of catechol can be immobilized on the electrode surface. Whole of the process is carried out in Triethylammonium acetate ionic liquid as an inert and neutral medium (pH∼7.0). Surface coverage can be easily controlled by the applied potential, time and concentration of catechol. After modification, the electrochemical features of modified surface have been studied. Also modified GC electrode exhibited remarkable catalytic activity in the oxidation of NADH. The catalytic currents were proportional to the concentration of NADH over the range 0.01-0.80 mM. This condition can be used for modification of GC surfaces by various aromatic molecules for different application such as design of sensors and biosensors. © 2014 Elsevier Ltd. All rights reserved

Direct C-S bond formation: Via C-O bond activation of phenols in a crossover Pd/Cu dual-metal catalysis system

A dual-metal catalysis system including a newly prepared nanoparticle [SiO 2 @organic-linker(OL)@Pd (II) ] and CuI was introduced with ultra-high catalytic activity (high turnover number (TON), up to 19000) to a one-pot and odorless synthesis of unsymmetrical aryl sulfides by crossover C-S bond formation. The reaction proceeds via C-O bond activation of phenols and direct C-S bond formation in the presence of S 8 as an oddorless sulfur source and aryl boronic acids under mild conditions (room temperature). The catalyst could be recycled up to five times without an obvious change in its activity. © 2019 The Royal Society of Chemistry

Fish Diets in Aquaponics

Fish and feed waste provide most of the nutrients required by the plants in aquaponics if the optimum ratio between daily fish feed inputs and the plant growing area is sustained. Thus, the fish feed needs to fulfil both the fish’s and plant’s nutritional requirements in an aquaponic system. A controlled fish waste production strategy where the nitrogen, phosphorus and mineral contents of fish diets are manipulated and used provides a way of influencing the rates of accumulation of nutrients, thereby reducing the need for the additional supplementation of nutrients. To optimize the performance and cost-effectiveness of aquaponic production, fish diets and feeding schedules should be designed carefully to provide nutrients at the right level and time to complement fish, bacteria and plants. To achieve this, a species-specific tailor-made aquaponic feed may be optimized to suit the aquaponic system as a whole. The optimal point would be determined based on overall system performance parameters, including economic and environmental sustainability measures. This chapter thus focuses on fish diets and feed and reviews the state of the art in fish diets, ingredients and additives, as well as the nutritional/sustainable challenges that need to be considered when producing specific aquaponic feeds.peerReviewe