Self-termination rate of para-substituted benzyl radicals in aqueous solutions: a time-resolved study

Mayouf, A.; Lemmetyinen, Helge; Koskikallio, Jouko

doi:10.1016/1010-6030(93)85046-b

Cited by 6 publications

(3 citation statements)

References 41 publications

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“…This is attributed to the decarbonylation reaction, which produces another equivalent of benzyl radicals. 4,5 On longer time-scales, the benzyl radical absorption depletes with second-order kinetics, 6,9,20 when oxygen is excluded. 11 This reaction corresponds to benzyl radical coupling, 2 which is known to be a diffusion-controlled reaction.…”

Section: Resultsmentioning

confidence: 99%

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Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Zhang

Nau

2000

J. Phys. Org. Chem.

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Section: Resultsmentioning

confidence: 99%

“…11 This reaction corresponds to benzyl radical coupling, 2 which is known to be a diffusion-controlled reaction. 6,9,20 A clear dependence of the signal intensity on the para substituent was not recognized (cf. normalized traces in Fig.…”

Section: Resultsmentioning

confidence: 99%

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Zhang

Nau

2000

J. Phys. Org. Chem.

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“…In addition, the benzyl radical can combine with itself or react with H atoms from H + + e s − , limiting the depth from which benzyl can evaporate (Sections S8 and S9). 23 We describe experiments below demonstrating that e s − reacts with BTMA + close enough to the surface to generate benzyl radicals and TMA that escape into the gas phase. The average e s − reaction depth is estimated to be only 20 Å, spanning a distance of roughly two BTMA + molecules.…”

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confidence: 99%

Creation and Reaction of Solvated Electrons at and near the Surface of Water

et al. 2023

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Solvated electrons (es –) are among nature’s most powerful reactants, with over 2600 reactions investigated in bulk water. These electrons can also be created at and near the surface of water by exposing an aqueous microjet in vacuum to gas-phase sodium atoms, which ionize into es – and Na+ within the top few layers. When a reactive surfactant is added to the jet, the surfactant and es – become coreactants localized in the interfacial region. We report the reaction of es – with the surfactant benzyltrimethylammonium in a 6.7 M LiBr/water microjet at 235 K and pH = 2. The reaction intermediates trimethylamine (TMA) and benzyl radical are identified by mass spectrometry after they evaporate from solution into the gas phase. Their detection demonstrates that TMA can escape before it is protonated and benzyl before it combines with itself or a H atom. Diffusion-reaction calculations indicate that es – reacts on average within 20 Å of the surface and perhaps within the surfactant monolayer itself, while unprotonated TMA evaporates from the top 40 Å. The escape depth exceeds 1300 Å for the more slowly reacting benzyl radical. These proof-of-principle experiments establish an approach for exploring the near-interfacial analogues of aqueous bulk-phase radical chemistry through the evaporation of reaction intermediates into the gas phase.

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Absolute Rate Constants for the Addition of Benzyl (PhĊH₂) and Cumyl (PhĊMe₂) Radicals to Alkenes in Solution

Walbiner

Fischer

1995

Helvetica Chimica Acta

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Absolute rate constants and their temperature dependence were determined by time‐resolved electron spin resonance for the addition of the radicals PhĊH2 and PhĊMe2 to a variety of alkenes in toluene solution. To vinyl monomers CH2=CXY, PhĊH2 adds at the unsubstituted C‐atom with rate constants ranging from 14 M−1S−1 (ethoxyethene) to 6.7 · 103 M−1S−1 (4‐vinylpyridine) at 296 K, and the frequency factors are in the narrow range of log (A/M−1S−1) = 8.6 ± 0.3, whereas the activation energy varies with the substituents from ca. 51 kJ/mol to ca. 26 kJ/mol. The rate constants and the activation energies increase both with increasing exothermicity of the reaction and with increasing electron affinity of the alkenes and are mainly controlled by the reaction enthalpy, but are markedly influenced also by nucleophilic polar effects for electron‐deficient substrates. For 1,2‐disubstituted and trisubstituted alkenes, the rate constants are affected by additional steric substituent effects. To acrylate and styrenes, PhĊMe2 adds with rate constants similar to those of PhĊH2, and the reactivity is controlled by the same factors. A comparison with relative‐rate data shows that reaction enthalpy and polar effects also dominate the copolymerization behavior of the styrene propagation radical.

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Self-termination rate of para-substituted benzyl radicals in aqueous solutions: a time-resolved study

Cited by 6 publications

References 41 publications

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Creation and Reaction of Solvated Electrons at and near the Surface of Water

Absolute Rate Constants for the Addition of Benzyl (PhĊH₂) and Cumyl (PhĊMe₂) Radicals to Alkenes in Solution

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Self-termination rate of para-substituted benzyl radicals in aqueous solutions: a time-resolved study

Cited by 6 publications

References 41 publications

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Aryl substituent effects and solvent effects on the decarbonylation of phenacetyl radicals

Creation and Reaction of Solvated Electrons at and near the Surface of Water

Absolute Rate Constants for the Addition of Benzyl (PhĊH2) and Cumyl (PhĊMe2) Radicals to Alkenes in Solution

Contact Info

Product

Resources

About

Absolute Rate Constants for the Addition of Benzyl (PhĊH₂) and Cumyl (PhĊMe₂) Radicals to Alkenes in Solution