3009-50-5Relevant academic research and scientific papers
Mechanism of Azo Coupling Reactions: Part XXXVI. The Relationship between the Structure and the Catalytic Activity of Anionic Phase-Transfer Catalysts in Azo Coupling Reactions
Iwamoto, Hidetoshi,Kobayashi, Hiroshi,Murer, Pius,Sonoda, Takaaki,Zollinger, Heinrich
, p. 2590 - 2602 (2007/10/02)
A series of 15 sodium arenesulfonates containing alkyl, hydroxyl or methoxyl groups was investigated for the phase-transfer catalysis of the azo coupling reaction of the 4-methoxybenzenediazonium ion (1) with 1,3,5-trimethoxybenzene (2) in a dichloromethane/water two-phase system, in which the yields, initial reaction rates and influence of the decomposition of the diazonium ion 1 were measured.The influence of counter anions on the partition coefficient (α) for the diazonium ion 1 in a dichloromethane/water system, and the effects of the solvent polarity and structure of counter anions on the reaction rates of the azo coupling of the diazonium ion 1 with N,N-dimethylaniline (4) and 1,3,5-trimethoxybenzene (2) in organic solvents and in dichloromethane/water system, were investigated.The symmetrical structure of the tetrakisborate (TFPB) anion was proved to be an essential factor regarding the remarkably high α for the diazonium ion 1 ion-paired with TFPB.The looseness and tightness of ion pairs of highly desolvated diazonium ion 1 in a nonpolar organic media is one of the most significant factors concerning the reactivity of the diazonium ion 1 in a rate-limiting azo coupling with 4.In a reaction of the diazonium ion 1 with 2 in a dichloromethane/water system, however, the amount of saturated water and/or additives in the dichloromethane phase, which serves as a base for the rate-limiting deprotonation, becomes the most influential factor for an effective azo coupling reaction under phase-transfer catalysis conditions.
Phase-Transfer-Catalyzed Azo Coupling Reactions in Two-Phase Systems
Hashida, Yoji,Kubota, Kazuhiro,Sekiguchi, Shizen
, p. 905 - 910 (2007/10/02)
The azo coupling reaction of p-methoxybenzenediazonium tetrafluoroborate with N,N-dimethylaniline has been investigated in a water-1,2-dichloroethane system.It has been found that, among the several additives examined, the phenolate ion, generated from picric acid or 2,4-dinitro-1-naphthol, acted as an effective phase-transfer catalyst.Further, the reaction of p-diethylaminobenzenediazonium tetrafluoroborate with dimedone, and active methylene compound, has also been investigated in the same two-phase system; a remarkable acceleration in the rate was observed in the presence of tetraalkyl onium salts, and even in their absence.
Photochemical Decomposition of 4-Arylazo- and 4-Arylazoxy-N,N-dialkylaniline N-Oxides
Albini, Angelo,Fasani, Elisa,Moroni, Micaela,Pietra, Silvio
, p. 1439 - 1444 (2007/10/02)
The 4-aryl-N,N-dialkylaniline N-oxides (1a-c) decompose on u.v. irradiation in aprotic solvents, undergoing deoxygenation as well as intramolecular hydrogen abstraction, to give amides and dealkylated products.The latter process is more important for the diethyl derivative (1b) (photoCope elimination).Visible irradiation is ineffective.The 4-arylazoxy-N,N-dialkylaniline N-oxides (2a-d) undergo photochemical deoxygenation from the amino group (major process) as well as from the azo group.The mechanism of these photoprocesses is discussed in general and in relation to the possible involvement of these N-oxide derivatives in photofading of the related azo dyes.
Mechanisms of Diazo Coupling Reactions. Part XXXI. Aminoazo Formation in the Diazo Coupling of N,N-Dimethylaniline and m-Toluidine with p-Methoxybenzenediazonium Tetrafluoroborate in Acetonitrile
Penton, John R.,Zollinger, Heinrich
, p. 1728 - 1738 (2007/10/02)
In the title reactions it is shown that aminoazo formation does not occur by direct attack of diazonium ion at C-atom.Initial attack is at N-atom, but proton loss from the ?N-complex formed is relatively slow.Hence, at low amine concentration t
