Muonium atom addition to 1,1-dimethylallene

Rhodes, Christopher J.; Symons, Martyn C. R.; Roduner, Emil; Scott, Christopher A.

doi:10.1016/0009-2614(87)87329-3

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…At lower temperatures, the smaller hfc decreases and the larger hfc increases, as shown in Table . These data are consistent with the values (at 210 and 288 K) found by Rhodes et al and assigned to the 1,1-dimethylallyl radical 1a and the substituted vinyl radical 1b (see Scheme ). It is 1a that has the smaller hfc.…”

Section: Resultssupporting

confidence: 92%

“…A smaller, positive temperature-dependence is evident (Table 1) for the muon hfc in 1a, where Mu is attached to C2. This is in accord with the previous µSR study 17 as well as earlier ESR results on similar 1-substituted allyl radicals. 22 It is consistent with torsional oscillations about C2, resulting in - overlap between the C-Mu(H) bond and the singly-occupied molecular orbital.…”

Section: Scheme 1 Muonium Addition To 11-dimethylallene (1)supporting

confidence: 94%

“…[12][13][14][15] Allyl radicals derived from dienes were among the earliest to be detected by µSR, 12,16 and subsequent work included Mu addition to 1,1dimethylallene. 17 However, these studies employed only the transverse-field muon spin rotation technique (TF-µSR), which allows the determination of the muon hyperfine constant (hfc) but does not provide information on the hfcs of other spin-active nuclei (e.g. protons in alkyl and allyl radicals).…”

Section: Introductionmentioning

confidence: 99%

“…Despite the light nucleus ( m μ = 0.1134 u), the reduced mass of the atom is close to that of H, so Mu can be viewed as a light isotope of hydrogen. − The muon is radioactive (lifetime τ = 2.2 μs) and has spin ( I = 1/2), which makes it a very selective probe of complex reaction systems. When Mu adds to an unsaturated molecule, the resulting muoniated radical can be detected by muon spin spectroscopy (μSR). − Allyl radicals derived from dienes were among the earliest to be detected by μSR, , and subsequent work included Mu addition to 1,1-dimethylallene . However, these studies employed only the transverse-field muon spin rotation (TF-μSR) technique, which allows the determination of the muon hyperfine constant (hfc) but does not provide information on the hfcs of other spin-active nuclei (e.g., protons in alkyl and allyl radicals).…”

Section: Introductionmentioning

confidence: 99%

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Free Radicals Formed by H Atom Addition to Allenes as Determined by Muon Spin Spectroscopy

Scollon

Percival

2020

J. Phys. Chem. A

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Allyl and vinyl radicals are important intermediates in diverse areas of chemistry, ranging from combustion to synthesis. However, questions remain about the competitive formation of these radicals from allenes. Here we present a study of prototypical allyl and vinyl radicals formed by H atom addition to allenes. They were studied by forming the analogous muonium adducts, since muonium (Mu) behaves as a light isotope of hydrogen, and muoniated species can be characterized by muon spin spectroscopy. Two techniques were employed: Transverse-Field Muon Spin Resonance (TF-μSR), and Muon Level Crossing Resonance (µLCR), which allow for the measurement of muon hyperfine constants (hfcs) and other nuclear hfcs, respectively, and thus aid identification of the formed radicals. TF-μSR has already been used to determine that two radicals are formed by Mu addition to 1,1-dimethylallene, but µLCR techniques were undeveloped at the time of that study, so assignments were based on ESR data of similar allyl and vinyl radicals. We report here the muon spin spectroscopy of multiple radicals detected from positive muon irradiation of 1,1-dimethylallene and 1-methoxyallene in solution. The radicals were identified by comparison of muon and proton hfcs with ESR data and the results of DFT calculations. The conclusion is that muonium (and by extension, the H atom) can add to all three carbons of the allene system, albeit with preference for the central carbon.

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Section: Resultssupporting

confidence: 92%

Section: Scheme 1 Muonium Addition To 11-dimethylallene (1)supporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Free Radicals Formed by H Atom Addition to Allenes as Determined by Muon Spin Spectroscopy

Scollon

Percival

2020

J. Phys. Chem. A

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Formation of Chemical States Incorporating Muons

2024

Muon Spin Spectroscopy

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EPR study of β‐methylene proton magnetic inequivalence in monomeric addition radicals derived from mono‐ and 1,1′‐disubstituted ethylenes with chiral and non‐chiral substituents

Smith

Donovan

Mader

et al. 1995

Magnetic Reson in Chemistry

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Using rapid-mixing, continuous-flow TiCI,-based techniques at 25 "C monomeric addition radicals of general formula 'CX(Y)CH,C*HRIRZ, where R' and RZ are different groups, neither being H, 90 that C* is a chiral center, were characterized by electron paramagnetic resonance. These species were generated by adding 'CH(CH,)OH, 'CH(CH,)OCH,CH, , 'CH(CH,)OC(O)H, 'CH(CH,)OC(O)CH, and 'kHCHzOCHzCHzO radicals in turn to each of the monomers, of general structure CX(Y)=CH, , acrylonitrile, acrylic acid, tert-butyl acrylate, butyl acrylate, methacrylonitrile, methacrylic acid, itaconic acid and but-3-ene-1,2,3-tricarboxylic acid. Similar reactions of carbon-centered radicals with vinyl fluoride and 1,l-difluoroethylene did not yield detectable levels of the expected addition radicals. In every addition radical observed, the splittings of the B-CH, protoy were found to be unequal and the size of this inequivalence varied qualitatively with the bulkiness of X, Y, R' and RZ. Similar measurements on monomeric addition radicals of general formula 'CX(Y)CH,Z, where Z is achiral, generated in turn from the same monomers by adding 'OH, 'NH, and 'CHOCH,OCH,d, showed no evidence for the fl-CH, proton splitting to be unequal. These results demonstrate the importance of an awareness of chirality effects in interpreting EPR spectra of monomeric and polymeric addition radicals of mono-and 1,l'-disubstituted etbylenes.

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Muonium atom addition to 1,1-dimethylallene

Cited by 11 publications

References 13 publications

Free Radicals Formed by H Atom Addition to Allenes as Determined by Muon Spin Spectroscopy

Free Radicals Formed by H Atom Addition to Allenes as Determined by Muon Spin Spectroscopy

Formation of Chemical States Incorporating Muons

EPR study of β‐methylene proton magnetic inequivalence in monomeric addition radicals derived from mono‐ and 1,1′‐disubstituted ethylenes with chiral and non‐chiral substituents

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