- Self-assembled palladium-organic composite nanofibers and their applications as a recyclable catalyst
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We report the formation of palladium nanoparticle (PdNP)-lithocholic acid (LCA) composite nanofibers by the self-assembly of Pd2+-coordinated LCA molecules and an ex situ reduction. The ex situ reduction by sodium borohydride or ascorbic acid p
- Bera, Tanmay,Fang, Jiyu
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- Transfer Hydrogenation of Azo Compounds with Ammonia Borane Using a Simple Acyclic Phosphite Precatalyst
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Tris(quinolin-8-yl)phosphite, P(Oquin)3, promotes the dehydrogenation of H3N·BH3 (AB) and the transfer hydrogenation of azoarenes using ammonia borane (AB) as H2 source. The metal-free reduction of azoarenes proceeds under mild reaction conditions upon which several diphenylhydrazine derivatives are obtained in high yields. The reactivity of P(Oquin)3 toward AB was evaluated through NMR in situ tests. The rate of the reaction, activation parameters, deuterium kinetic isotope effect (DKIE) and linear-free energy relationship were investigated. Such mechanistic and kinetic studies suggest that P(Oquin)3 is a precatalyst and that AB is likely involved in more than one stage of the reaction pathway. Furthermore, the kinetic data indicate that the reaction proceeds through an ordered transition state, possibly associative.
- Chacón-Terán, Miguel A.,Rodríguez-Lugo, Rafael E.,Wolf, Robert,Landaeta, Vanessa R.
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supporting information
p. 4336 - 4344
(2019/08/20)
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- Structure requirements for anaerobe processing of azo compounds: Implications for prodrug design
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This Letter generalizes the metabolism of the azo class of compounds by Clostridium perfringens, an anaerobe found in the human colon. A recently reported 5-aminosalicylic acid-based prednisolone prodrug was shown to release the drug when incubated with the bacteria, while the para-aminobenzoic acid (PABA) based analogue did not. Instead, it showed a new HPLC peak with a relatively close retention time to the parent which was identified by LCMS as the partially reduced hydrazine product. This Letter investigates azoreduction across a panel of substrates with varying degrees of electronic and steric similarity to the PABA-based compound. Azo compounds with an electron donating group on the azo-containing aromatic ring showed immediate disproportionation to their parent amines without any detection of hydrazine intermediates by HPLC. Compounds containing only electron withdrawing groups are partially and reversibly reduced to produce a stable detectable hydrazine. They do not disproportionate to their parent amines, but regenerate the parent azo compound. This incomplete reduction is relevant to the design of azo-based prodrugs and the toxicology of azo-based dyes.
- Gavin, Jason,Ruiz, Juan F. Marquez,Kedziora, Kinga,Windle, Henry,Kelleher, Dermot P.,Gilmer, John F.
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p. 7647 - 7652
(2013/02/21)
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- Tin-mediated reduction of azoarenes to hydrazoarenes using hydrazine hydrate
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The controlled reduction of azoarenes to the corresponding hydrazoarenes using tin and hydrazine hydrate is reported. The reduction proceeds smoothly at room temperature furnishing the hydrazoarene in excellent yield without the formation of an aniline.
- Dinesh,Abiraj,Srinivasa,Gowda, D. Channe
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p. 422 - 423
(2007/10/03)
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- Facile Transfer Hydrogenation of Azo Compounds to Hydrazo Compounds and Anilines by Using Raney Nickel and Hydrazinium Monoformate
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Azo compounds are conveniently reduced to either partially reduced hydrazo compounds or completely reduced anilines by employing Raney nickel in presence of hydrazinium monoformate depending upon reaction conditions. The other reducible moieties like -COOH and halogens are tolerated. The reduction process is selective, rapid and high yielding.
- Prasad,Gowda, Shankare,Gowda, D. Channe
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- Ammonium chloride mediated reduction of azo compounds to hydrazo compounds
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The reduction of azo compounds with magnesium powder as catalyst in the presence of ammonium chloride at room temperature in methanol leads to hydrazo compounds.
- Sridhara,Srinivasa,Gowda, D. Channe
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- Reactions of Azoarenes with Tributyltin Hydride
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Tributyltin hydride when reacted with a series of substituted azoarenes afforded hydrazo compounds with high chemoselectivity and good to high yields.With ortho-substituted azoarenes, mixtures of hydrazo derivatives and N-heterocycles or cyclic products only were obtained.The kinetic law of the process was determined in the presence and in the absence of AIBN; with the radical initiator the reaction proceeds via a radical chain mechanism, whereas without AIBN the presence of stannyl free radicals could be discarded.The mechanism of the noninitiated reaction is discussed.EPR characterization of spin adducts obtained by reacting group IVB organometallic radicals with azo compounds is reported.
- Alberti, Angelo,Bedogni, Nicola,Benaglia, Massimo,Leardini, Rino,Nanni, Daniele,et al.
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p. 607 - 613
(2007/10/02)
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