- 1,4-Diamino- and 1,4-Dibutylamino-anthraquinones: Reduction and/or Deprotonation-initiated Elimination of the Butyl Groups in Dipolar Aprotic Media
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The standard redox potentials of the one- and two-electron reductions of the title compounds have been determined.The deprotonated form of the dibutylamino compound underwent a base-initiated elimination of the butyl groups and the basicity of the radical anion resulting from one-electron reduction was sufficient to provoke the same type of cleavage through an initial father-son reaction.A multi-step mechanism is proposed for the elimination on the basis of the identification of intermediates.
- Anne, Agnes
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p. 311 - 318
(2007/10/02)
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- Kinetics and product studies on Ullmann amination of 1-halogenoanthraquinones catalysed by copper(I)salts in acetonitrile solution
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The kinetics and products of reactions of some primary amines (RNH2) with 1-halogenoanthraquininone (AQX) promoted by copper salts, particularly tetrakis(acetonitrile)copper(I) tetrafluoroborate, have been investigated in acetonitrile solution at 70 deg C.Provided that oxygen does not come into contact with solutions of the copper(I) salt and amine, the kinetics of the reactions have the simple form v = k, and the products consist almost entirely of the aminated anthraquinone, AQNHR, and dehalogenated material, AQH, their ratio being directly proportional to .The reaction rate is dependent on the identity of the departing halogen X, decreasing in the sequence I > Br > Cl, but the product ratio is little affected.N-Deuteration of the reactant amine gives rise to a small kinetic isotope effect, but the product ratio is unaffected.Conversely deutearation on the α-carbon atom of the amine has little kinetic effect but leads to a four-fold increase in the ratio of aminated to dehalogenated product.The observations are interpreted in terms of (i) formation of a copper(I)-amine complex, (II) activation of this species for attack on AQX by proton abstraction from an amine ligand by a free molecule (stepwise or concerted), and (iii) generation of an arylcopper(III) intermediate which is partitioned between formation of AQNHR by attack of an externel amine molecule and formation of AQH by an intramolecular process involving hydrogen transfer from the α-carbon atom in the amine ligand generated in (ii).Exposure of the initial copper(I)-amine complex to oxygen leads to a new complex, itself capable of reacting with AQX, which on prolonged incubation at 70 deg C in the presence of an excess of amine is transformed back to its original state.
- Bethell, Donald,Jenkins, Iwan L.,Quan, Peter M.
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p. 1789 - 1796
(2007/10/02)
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- A new Synthesis of 1-Amino-4-butylaminoanthraquinone from 1-Aminoanthraquinone Promoted by Metal Ions
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In the presence of some metal ions and atmospheric oxygen, 1-aminoanthraquinone (1) reacts readily with butylamine to give 1-amino-4-butylaminoanthraquinone(2a), along with a small amount of 1,4-diaminoanthraquinone, which is produced by the dealkylation of 2a.The activity of the metal ions decreased in the following order: Co(II) >> Ni(II) above Cu(II) above Al(III).The reaction is remarkably affected by the substitution of an alkyl group into the amino group of 1, the addition of a chelating agent, the counter anion of metal ions, and the reaction temperature.By the use of cobalt(II) chloride, the reaction proceeds most smoothly at about 30 deg C.Both anthraquinone and 2-aminoanthraquinone show no sign of the reaction under the same conditions.A possible mechanism involving the formation of a metal complex, followed by the nucleophilic attack of amine at the 4-position and the oxidative abstraction of the hydride anion by atmospheric oxygen is proposed.
- Yoshida, Katsuhira,Matsuoka, Masaru,Yamashita, Yoshio,Kitao, Teijiro
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p. 2552 - 2554
(2007/10/02)
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- The Direct Alkylamination of 1-Aminoanthraquinone Promoted by Cobalt(II) Chloride
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The reaction of 1-aminoanthraquinone with primary aliphatic amines in the presence of cobalt(II) chloride under atmospheric oxygen preferentially gave the corresponding 1-amino-4-(alkylamino)anthraquinones.The reaction did not proceed with aqueous ammonia, bidentate amines, secondary aliphatic amines, and primary arylamines.While, with alicyclic amines the reaction mainly afforded 1-amino-2,4-bis(alkylamino)anthraquinones.
- Yoshida, Katsuhira,Matsuoka, Masaru,Yamashita, Yoshio,Nagamori, Shoichi,Kitao, Teijiro
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p. 3725 - 3726
(2007/10/02)
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