Structure-Reactivity Relationship in the Reaction of Highly Reactive Zinc with Alkyl Bromides

Guijarro, Albert; Rieke, Reuben D.

doi:10.1002/(sici)1521-3773(19980703)37:12<1679::aid-anie1679>3.0.co;2-b

Cited by 39 publications

(5 citation statements)

References 9 publications

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“…The kinetics of the reactions of both the electron rich radical anion and dianion with n -, s - and t -octyl fluorides were investigated. The relative rate constants were determined using competitive kinetic techniques. , The reactivity has been shown to decrease in the order primary > secondary > tertiary for reactions of octyl fluorides in both the naphthalene radical anion and dianion. This is the opposite of what would be intuitively expected if ET were the main process.…”

Section: Single Electron Transfer (Set)/sn2 Dichotomymentioning

confidence: 99%

Electron Transfer Initiated Reactions: Bond Formation and Bond Dissociation

2008

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Section: Single Electron Transfer (Set)/sn2 Dichotomymentioning

confidence: 99%

Electron Transfer Initiated Reactions: Bond Formation and Bond Dissociation

2008

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“…The reaction contemplated here can therefore be described as another example of a radical-mediated selective reaction , and it has straightforward synthetic applications. Some synthetic work was done in this direction, to demonstrate how this structure−reactivity dependence can be used to obtain selective organozinc formation in unsymmetrical dibromides 1 Plots displaying competitive alkylzinc bromide formation according to eq 4.…”

Section: Introductionmentioning

confidence: 99%

The Reaction of Active Zinc with Organic Bromides

1999

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The oxidative addition of highly reactive zinc to organic bromides shows a pronounced structure−reactivity dependence, in contrast to that shown by other metals. The kinetic and LFER studies suggest a mechanism in which electron transfer (ET) is the rate-determining step of the reaction. Experiments carried out with radical clocks as well as the stereochemical outcome of the reaction support the presence of radicals. The reactivity profiles suggest that the ET has an important component of inner-sphere process in the reaction with alkyl bromides. In the case of aryl halides, Hammet plots are consistent with the participation of aryl halide radical anions as intermediates. The reaction contemplated here can be ascribed as another example of radical-mediated selective reaction, and it has straightforward synthetic applications. Some synthetic work was done in this direction, to demonstrate how this structure−reactivity dependence can be used to obtain selective organozinc formation in unsymmetrical dibromides.

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“…To add to the original reactivity mysteries, unfortunately, Rieke published primarily qualitative reactivity comparisons of different preparations. A portion of these assessments were based on reactivity with different substrates, for example, the ability of Rieke zinc formed by a given preparation method to undergo direct insertion with less reactive organochlorides vs the typically more reactive organoiodides or organobromides. ,− ,,− While rational, such comparisons leave a gap in quantitative understanding (which is now partially addressed in this manuscript). We have compiled a collection of Rieke’s reactivity assessments in Figure b. ,, These reactivity assessments, though qualitative, currently appear to influence choices of other researchers.…”

Section: Introductionmentioning

confidence: 99%

Reactivity Differences of Rieke Zinc Arise Primarily from Salts in the Supernatant, Not in the Solids

et al. 2022

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Contrary to prevailing thought, the salt content of supernatants is found to dictate reactivity differences of different preparation methods of Rieke zinc toward oxidative addition of organohalides. This conclusion is established through combined singleparticle microscopy and ensemble spectroscopy experiments, coupled with careful removal or keeping of the supernatants during Rieke zinc preparations. Fluorescence microscopy experiments with single-Riekezinc-particle resolution determined the microscale surface reactivity of the Rieke zinc in the absence of supernatants, thus pinpointing its inherent reactivity independent of the convoluting supernatant composition. In parallel experiments, scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma-mass spectrometry characterized the zinc metal chemical composition at the bulk and single-particle levels. Proton nuclear magnetic resonance spectroscopy kinetics characterized bench-scale Rieke zinc reactivity in the presence and absence of different supernatants and exogenous salt additives. Together, these experiments show that the differences in reactivity from sodium-reduced vs lithium-reduced Rieke zinc arise from the residual salts in the supernatant rather than the differing salt compositions of the solids. This supernatant salt also determines the structure of the ultimate organozinc product, generating either the diorganozinc or monoorganozinc halide complex. That different organozinc complexes formed upon direct insertion to different preparations of Rieke zinc was not previously reported, despite Rieke zinc's widespread use. These findings impact organozinc-reagent and nanomaterial synthesis by showing that, unexpectedly, desired Rieke zinc reactivity can be achieved through simple addition of soluble salts to solutions that were used to prepare the metalsa substantially easier synthetic manipulation than solid composition and morphology control.

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Structure-Reactivity Relationship in the Reaction of Highly Reactive Zinc with Alkyl Bromides

Cited by 39 publications

References 9 publications

Electron Transfer Initiated Reactions: Bond Formation and Bond Dissociation

Electron Transfer Initiated Reactions: Bond Formation and Bond Dissociation

The Reaction of Active Zinc with Organic Bromides

Reactivity Differences of Rieke Zinc Arise Primarily from Salts in the Supernatant, Not in the Solids

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