Metal Vapor Reactivity of Copper Toward Substituted Bromobenzenes. Comparison with the Classical Ullmann Coupling Reaction

Négrel, Jean-Claude; Zoellner, Robert W.; Chanon, Michel; Chanon, F.

doi:10.1007/978-94-009-0877-2_8

Cited by 2 publications

(6 citation statements)

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“…The use of transition metal 0 in organic chemistry is well documented. Cu 0 is a classic SET donor used in the Ullmann reaction, the Pschorr reaction, the reductive dehalogenation of alkyl halides, in the Muller–Rochow process, as well as in SET-DTLRP and in SET-LRP. , All 3d metals were found reactive in the reductive dehalogenation of alkyl halides through SET mechanism …”

Section: Fundamentals Of Single Electron Transfer In Organic Synthesismentioning

confidence: 99%

“…However, the mechanism for the generation of organocuprous species was not discussed . Chanon’s group reported the formation of benzene and biphenyl by reacting 3d transition metal vapors with p -bromotoluene in methylcyclohexane solution . Cr was found to be most effective in dehalogenation reactions, while Ni was the most reactive for homocoupling reaction.…”

Section: Reductive Chemistrymentioning

confidence: 99%

“…A SET pathway was initially ruled out because the colors of transition metal vapor/bromotolunene mixture and Na/bromotolunene mixture were different. The authors concluded the process was atom transfer . However, in a later publication from the same group, the authors changed their opinion and proposed that the formation of alkyl radicals proceeded by a SET mechanism.…”

Section: Reductive Chemistrymentioning

confidence: 99%

“…8,105 All 3d metals were found reactive in the reductive dehalogenation of alkyl halides through SET mechanism. 106 2.2. 20,113 Common metal ions that disproportionate in aqueous solution include Cu + , 113,114 Cd 2 2+ , Mn 6+ , Hg 2 2+ , Sn 2+ , Ga + , In + , Au + , and Sm 2+ .…”

Section: Classes Of Electron Donors and Acceptorsmentioning

confidence: 99%

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Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

et al. 2014

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Section: Fundamentals Of Single Electron Transfer In Organic Synthesismentioning

confidence: 99%

Section: Reductive Chemistrymentioning

confidence: 99%

Section: Reductive Chemistrymentioning

confidence: 99%

Section: Classes Of Electron Donors and Acceptorsmentioning

confidence: 99%

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Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

et al. 2014

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“…[79,117] In these experiments, the magnesium (Mg*) is produced by in vacuo (6 ϫ 10 -4 mbar) vaporisation into a solution of THF maintained at -110°C. [118,119] Determination of the size of magnesium clusters formed shows that we are dealing with nanoparticles. [120] The black suspension of magnesium clusters can then be transferred to a Schlenk tube where it can be kept under argon in the fridge for several months without any loss of reactivity.…”

Section: Introductionmentioning

confidence: 99%

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism

et al. 2010

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Both SRN1‐type reactions and Grignard reagent formation are inhibited by trace amounts (with respect to the halide) of p‐dinitrobenzene (DNB) and other oxidising agents such as CuCl2 or dioxygen. Both are believed to be triggered by an electron‐transfer step. In this report we examine the patterns of reactivity shared by these two types of reaction. Although the two reactions display an amazing number of similarities, the chain character of the Grignard reaction mechanism has been rejected by major contributors to this field. We have performed new experiments to explore the inhibiting effect associated with the addition of trace amounts of p‐dinitrobenzene during Grignard reagent formation. This inhibition involves very reactive nanoparticles of magnesium prepared by metal vapour synthesis. The magnesium slurries studied, in the absence of p‐dinitrobenzene, display no induction period at all. If the p‐dinitrobenzene is added to the solution containing magnesium slurries 25 min before adding the organic halide (here bromobenzene), the reaction is neatly inhibited but, if one waits long enough, the Grignard reagent is nevertheless formed. If, however, the same trace amounts of p‐dinitrobenzene are diluted in the organic halide and this mixture is added to the magnesium slurries, the inhibiting effect is far less pronounced. The addition of the nBu4NBr salt drastically diminishes the inhibiting power of DNB. These observations, in addition to the ESR study of radical anions formed in THF by the reaction of magnesium nanoparticles and DNB with various polyaromatics, suggest a mechanism for the observed inhibitions that involves a series of reversible adsorptions of the present species. This adsorption would depend on both thermodynamic and kinetic factors. Thermodynamics would favour the adsorption of DNB radical anions but C–X bond cleavage of the less strongly adsorbed aromatic radical anions would provide a kinetic driving force for displacing the equilibria in the direction of Grignard reagent formation. Salt effects could operate by displacing the equilibrium – adsorbed DNB radical anion or dianion versus solvated radical anion (with the counterion nBu4N+) – to the right, accelerating therefore the liberation of active sites on the magnesium surface. It appears that the inhibiting effect of the same compound finds its origin in two different molecular series of events in SRN1 and in Grignard reagent formation. The heterogeneous character of the Grignard reagent makes it possible to envision the possibility of active sites even on nanoparticles, whereas the inhibition of the SRN1 mechanism by DNB occurs in homogeneous solution.

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Metal Vapor Reactivity of Copper Toward Substituted Bromobenzenes. Comparison with the Classical Ullmann Coupling Reaction

Cited by 2 publications

References 39 publications

Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism

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Metal Vapor Reactivity of Copper Toward Substituted Bromobenzenes. Comparison with the Classical Ullmann Coupling Reaction

Cited by 2 publications

References 39 publications

Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the SRN1 Mechanism

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About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism