- Ascorbic acid/iodine and triphenylphosphine/iodine as reducing agents for the As(V)=O group
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The scope of ascorbic acid/iodine and triphenylphosphine/iodine in methanol for the direct reduction of arsenic(V) compounds having the As=O group has been investigated. Ascorbic acid/iodine reduces arsonic acids, diphenylarsinic acid (but not dimethylarsinic acid), and triphenylarsine oxide. The rates of reduction depend on the electronic effects of the ligands bound to arsenic and on the hydrogen-bonding strength of the species, when present. When the As(V) compound has an -NH2 or an -NH3+ group, the reduction product reacts with a ketonic form of dehydroascorbic acid, giving condensation product(s). Triphenylphosphine/iodine reduced slowly the zwitterionic o-aminophenylarsonic acid but reduced faster the hydrochloric acid salt of the same acid. It reduced dimethylarsinic acid as well because the powerful electron-withdrawing Ph3P+coordinated to As=O seems to outweigh the electronic and hydrogen bonding effects. Copyright Taylor & Francis Group, LLC.
- Sideris, Theodore D.,Ioannou, Panayiotis V.
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- α-cationic arsines: Synthesis, structure, reactivity, and applications
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A series of structurally differentiated cationic arsines containing imidazolium, cyclopropenium, formamidinium, and pyridinium substituents have been synthesized through short and scalable routes. Evaluation of the donor properties of these compounds by IR spectroscopy and DFT calculations reveals similar σ-electron-releasing abilities for all of them; however, their π-acceptor properties are strongly influenced by the nature of the positively charged group. We describe the coordination chemistry of the newly prepared α-cationic arsines toward different metal centers and their reactivity in the presence of strong oxidants to afford cationic As(V) species. Their unique electronic properties have been exploited in Pt(II) catalysis to develop a new catalyst with remarkable activity in the cycloisomerization of enynes to trisubstituted cyclopropanes. To the best of our knowledge, this is the first report on the use of α-cationic arsine ligands in catalysis.
- Dube, Jonathan W.,Zheng, Yiying,Thiel, Walter,Alcarazo, Manuel
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p. 6869 - 6877
(2016/06/14)
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- Phosphides and Arsenides as Metal-Halogen Exchange Reagents. Part 2. Reactions with Aromatic Dihalides
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1,2-Dihalogenobenzenes react with two molar equivalents of lithium diphenylphosphide in the presence of furan to give, after oxidation, triphenylphosphine oxide (major) and the corresponding 2-halogenophenyldiphenylphosphine oxide.No trace of furan-dehydrobenzene adduct was observed in these reactions; however, 1- and 2-naphthyldiphenylphosphine oxides (9:4) were detected.These compounds were the major products from the reaction of the furan-dehydrobenzene adduct with diphenylphosphide, although the ratio of 1- to 2-isomers was quite different (1:9) in this case.Reaction of lithium diphenylphosphide with 3,4-dichloronitrobenzene gave tetrachloroazobenzene (40percent) as the only isolated product and attempts to replace 1,2-dihalogenobenzenes with 2-halogenobenzenediazonium salts gave much lower yields of products.Although dehydrobenzene is thought to be involved in many of these reactions, alternative mechanisms also operate, depending on the halides used.The reaction of lithium diphenylarsenide with 1,2-dihalogenobenzenes gave triphenylarsine as the major product and it seems likely that similar mechanisms to those involved in reactions of diphenylphosphide are operating.Surprisingly, dehydrobenzene-furan adduct reacted with diphenylarsenide to give naphthalene in high yield.
- Gillespie, Donal G.,Walker, Brian J.,Stevens, David,McAuliffe, Charles A.
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p. 1697 - 1703
(2007/10/02)
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- New Reagents, XVIII. (Lithiomethyl)diphenylarsane Oxide; Synthesis and Application for the Indirect Nucleophilic Halomethylation
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Due to its ready accessibility and high nucleophilicity (lithiomethyl)diphenylarsane oxide (2b) is a favorable reagent for the synthesis of many organoarsenic compounds.In organic synthesis it is recommendable as a reagent for indirect nucleophilic halomethylations (Hal = Cl, Br, I).
- Kauffmann, Thomas,Fischer, Heinz,Woltermann, Annegret
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p. 645 - 653
(2007/10/02)
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- Chemistry of Polyfunctional Ligands, 60 On Cage Compounds with the Heteroelements Arsenic and Selenium
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The reaction of 1,1,1-tris(diiodoarsinomethyl)ethane, CH3C(CH2AsI2)3 (1) with NaAs(C6H5)2 in the molar ratio of 1:3 gives 4-methyl-1,2,6-triarsa-tricyclo2,6>-heptane, CH3C(CH2As)3 (2).The previously synthesized CH3C(CH2AsS)3 (4) can be desulphurated with triphenylphosphine to yield also 2.The reaction of 1 with NaSeH gives the new cage compound 6-methyl-1,3,4-triarsa-2,8-diselena-tricyclo3,4>-nonane, CH3C(CH2As)3Se2 (5). - Keywords: Hetero Cage Compounds, Synthesis, Vibrational Spectra, Mass Spectra, 1H NMR Spectra
- Ellermann, Jochen,Lietz, Martin
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p. 1514 - 1517
(2007/10/02)
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