Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVII. Kinetics and mechanisms of dediazoniation of <i>p</i>‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions in the presence of oxygen

Besse, Jacques; Zollinger, Heinrich

doi:10.1002/hlca.19810640217

Cited by 11 publications

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“…Kinetic evidence is also given for the formation of the diazo anhydride. 56 It is not difficult to realize that most of the aboveexamined reactions present common features with the thermolysis of azo compounds8,13,60,154 (eq 37). It is also PhN=NCPh3 -Ph* + N2 + *CPh3 (37) clear that there is always the risk, with strongly nucleophilic anions, of interference by the heterolytic mechanism, particularly when the nucleophiles are not good electron donors: typical is the case of fluoride ion.…”

Section: Cuxomentioning

confidence: 99%

“…The reaction was first believed to be heterolytic.38 Subsequently, the homolytic mechanism was preferred,39 but the involvement of a cryptoradical was suggested,49,50 until the identity of the reductant was clarified by Kochi. He showed195,222 that some of the Cu(II) ion is reduced by the solvent acetone to a Cu(I) species (eq 56), which then provides the required electron-transfer CuCl2 + CH3COCH3 -CuCI + C1CH2C0CH3 + H+ (56) step. 223 The resulting aryl radical adds to the double bond giving the intermediate 9, which on ligand transfer leads to what is a homologation product (pathway a) of a Sandmeyer reaction (Scheme 22).…”

Section: Addition To Olefinsmentioning

confidence: 99%

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Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

Galli¹

1988

Chem. Rev.

712

490

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Contents I. Introduction 765 II. Evolution of the Mechanistic View of the 766 Diazonium Group Replacement III. Homolytic Dediazoniation Reactions: A 769 General Description A. How the Homolytic Dediazoniation Takes 769 Place 1. Reduction at the Electrode 769 2. Radiolytic Approach 770 3. Photoinduced Electron Transfer 770 4. Reduction by Metal Cations 771 5. Anion-Induced Dediazoniation 772 6. Solvent-Induced Dediazoniation 775 7. Summary 776 B. Product Patterns of the Aryl Radical 777 1. Hydrogen Atom Abstraction 777 (Hydro-dediazoniation) 2. Reaction with X' (Halo-dediazoniation) 777 3. Other Sandmeyer-like Reactions 779 4. Addition to Olefins 779 5. Arylation of Aromatic Compounds 781 6. Conclusions 782 IV. Related Reactions 782 A. Intermediacy of the Aryl Radical 782 1. Reactions of Diaryliodonium Ions 783 2. SRN1 Reactions 784 B. Interchange of Product Patterns 786 V. Unrelated Reactions 788 VI. Acknowledgment 789 VII. References 789

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Section: Cuxomentioning

confidence: 99%

Section: Addition To Olefinsmentioning

confidence: 99%

Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

Galli¹

1988

Chem. Rev.

712

490

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“…The analytical procedure for experiment S87/90 was the most accurate and the most elaborate. publications concerning the kinetics of decomposition of this diazonium ion in the same pH-range [3] [4], we now report on the products formed under these conditions.…”

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Dediazoniations of Arenediazonium Ions in Homogeneous Solutions. Part XV. Products of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions

Besse¹,

Schwarz²,

Zollinger³

1981

Helvetica Chimica Acta

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SummaryThe products of decomposition of solutions of p-chlorpbenzenediazonium tetrafluoroborate in aqueous buffer solutions (pH 9.0-10.3; ionic strength 0.1-0.5) at 20.0" have been analyzed quantitatively. Up to eleven low molecular weight compounds could be identified besides the major product, the complex polymeric diazo tar. The distribution of products is influenced by trace amounts of oxygen as well as by p-chlorophenol and the radical trapping reagent iodoacetic acid. Mechanisms of formation of the products are discussed.1. Introduction. -The reaction products of arenediazonium ions in aqueous solutions depend on acidity, and three main areas of interest with respect to pH can be defined. In the case of the unsubstituted benzenediazonium ion heterolytic hydroxydediazoniation is dominant below about pH 4, and phenol is formed. At pH-values higher than 12, cis-benzenediazotate (originally called syn-diazotate) is formed; it is rearranged slowly into the trans-diazotate (anti-diazotate). In the intermediate pH-range a number of products can be detected, in particular the so-called diazo tars, i.e. macromolecular compounds of a complex structure which has not yet been investigated in detail2). For substituted benzenediazonium ions the above pH ranges are shifted to higher and lower values, depending on the basifying and acidifying character, respectively, of the substituents.The mechanisms of heterolytic hydroxydediazoniation and hydroxyaddition have been investigated in detail. In contrast, only a few mechanistic studies have been made of reactions of diazonium ions in the medium range of pH values (pH 6-11) in spite of the fact that solutions of diazonium salts are often used for the synthesis of azo dyes in precisely this pH range. The lack of data.on the fate of diazonium salts in slightly alkaline solutions is due to the complex mixture of products and to the difficulty in reproducing the kinetic data.

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“…In the field of dediazoniations we refer e.g. to the extensive discussion of potential mechanisms of the reaction of diazonium ions with nitrite ion given by Opgenorth [2 11 or to our following paper on the decomposition of p-chlorobenzenediazonium ion solutions in glass and in polytetrafluoroethylene vessels [3].…”

Section: + Homentioning

confidence: 99%

“…small concentrations of O2 (60 to 100 ppb) the kinetics are significantly different as we shall show in a subsequent paper [3].…”

mentioning

confidence: 90%

Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVI. Kinetics and mechanisms of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions under nitrogen gas

Besse¹,

Zollinger²

1981

Helvetica Chimica Acta

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SummaryThe kinetics of reactions of p-chlorobenzenediazonium ions in aqueous buffer solutions (pH 9.0-10.6) under N, (< 5 ppb of 0,) have been measured between 20 and 50°C. The formation of trans-diazotate is first-order with respect to the concentration of hydroxyl ions and to the equilibrium concentration of diazonium ions, if the diazonium ion+cis-diazotate equilibrium is considered as a fast prior equilibrium. This indicates that the p-chlorobenzenediazonium ion, in contrast to all previous investigations with the p-nitrobenzenediazonium ion and benzenediazonium ions carrying similar substituents with a -M effect, rearranges from the cis-to the trans-configuration as diazohydroxide and not as diazotate. The formation of trans-diazotate is catalyzed by carbonate and inhibited by hydrogen carbonate ions; mechanisms of these catalyses are discussed, and the solvent isotope effect KH20/KD20 measured by an 'H-NMR. technique reported. The kmetics of the dediazoniations can be analyzed as a mixture of two reactions, a relatively fast first reaction, reaction A, which is responsible for about 5% of the total reaction, and a second reaction F. Both are first-order with respect to diazonium ion; reaction A is also first-order in hydroxyl ions. There are some indications that reaction A corresponds to the hydrolysis of the diazonium ion to give eventually amine and nitrite ions. Reaction F shows a complex dependence on hydroxyl ions; it is related to the homolytic dediazoniation.

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Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVII. Kinetics and mechanisms of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions in the presence of oxygen

Cited by 11 publications

References 14 publications

Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

Dediazoniations of Arenediazonium Ions in Homogeneous Solutions. Part XV. Products of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions

Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVI. Kinetics and mechanisms of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions under nitrogen gas

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