Unstable intermediates

Rosenbaum, J. H.; Symons, M. C. R.

doi:10.1080/00268976000100251

Cited by 24 publications

(4 citation statements)

References 23 publications

(30 reference statements)

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“…22 Primary carbonium ions, like the «-alkyllithiums, have no absorption maxima in the near ultraviolet. 21 Conjugated Organolithiums.-Our observation of the absorption maximum of allyllithium is in agreement with a theoretical estimate of 326 µ for the absorption of allylcarbanion.12 The spectrum of allylsodium is reported12 to contain two absorption maxima, a short wave length band comparable to our finding for allyllithium and a longer wave length band not evident in the spectrum of allyllithium. This longer wave length absorption could be caused by a decomposition product, as suggested below for Kuwata's12 findings for the spectrum of benzylsodium.…”

Section: Resultssupporting

confidence: 87%

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Electronic Spectra of Organolithium Compounds

Waack¹,

Doran²

1963

J. Am. Chem. Soc.

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Section: Resultssupporting

confidence: 87%

“…The possibility of near ultraviolet absorption by sec-and terf-butyllithium compounds was suggested by a recent report of absorption maximum ~295 µ for sec-and /srf-alkylcarbonium ions. 21 This has recently been questioned, however. 22 Primary carbonium ions, like the «-alkyllithiums, have no absorption maxima in the near ultraviolet.…”

Section: Resultsmentioning

confidence: 99%

Electronic Spectra of Organolithium Compounds

Waack¹,

Doran²

1963

J. Am. Chem. Soc.

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“…Therefore, chemical processes that comprise alkyl radicals have an essential effect on the disintegration of organic materials . Because most alkyl radicals are active and unstable, , it is challenging to monitor their experimental methods. Thus, the mechanism of carbene formation is investigated through TSK.…”

Section: Resultsmentioning

confidence: 99%

Thermal Degradation and Bimolecular Decomposition of 2-Ethoxyethanol in Binary Ethanol and Isobutanol Solvent Mixtures: A Computational Mechanistic Study

et al. 2021

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A thorough computational study of a thermal degradation mechanism of 2-ethoxyethanol (2-EE) in the gas phase has been implemented using G3MP2 and G3B3 methods. The stationary point geometries were optimized at the B3LYP functional utilizing the 6-31G(d) basis set. Intrinsic reaction coordinate analysis was performed to determine the transition states on the potential energy surfaces. Nineteen primary different reaction mechanisms, along with the kinetic and thermodynamic parameters, are demonstrated. Most of the thermal degradation mechanisms result in a concerted transition state step as an endothermic process. Among 11 degradation pathways of 2-ethoxyethanol, the formation of ethylene glycol and ethylene is kinetically significant with an activation energy of 269 kJ mol–1 at the G3B3 method. However, the kinetic and thermodynamic calculations indicate that ethanol and ethanal’s formation is the most plausible reaction with an activation barrier of 287 kJ mol–1 at the G3B3 method. For the bimolecular dissociation reaction of 2-ethoxyethanol with ethanol, the pathway that produces ether, H2, and ethanol is more likely to occur with a lower activation energy of 221 kJ mol–1 at the G3B3 method. Thus, 2-EE has experienced a set of complex unimolecular and bimolecular reactions.

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“…(C8H10O2) C, H. Band 3 (238.5 mg) contained 5-ethyl-6-methyl-2//-pyran-2-one. The spectral data follow: NMR, IR, UV (Table I); mass spectrum m/e 138 (49), 123 (18), 110 (40), 95 (86), 77 (45), 67 (29), 43 (100), 41 (19), 39 (19). Anal.…”

Section: Methodsmentioning

confidence: 99%

Heterocyclic photochemistry. 1. Phototranspositions in hydroxypyrylium cations. Permutation pattern analysis and mechanistic studies

Barltrop¹,

Barrett²,

CARDER³

et al. 1979

J. Am. Chem. Soc.

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A number of dialkyl-4-pyrones have been irradiated (as the corresponding 4-hydroxypyrylium cations) in sulfuric acid and the transposed 2-pyrones have been identified. A permutation pattern analysis of these and literature data shows that the photorearrangement follows a P4 permutation pattern, thus defining the fate of all the ring atoms. This conclusion is supported by a total-labeling investigation: a study of the rearrangement of a l4C-labeled 4-pyrone confirmed that the alkyl migrations are intramolecular, the alkyl groups remaining bonded to the ring atoms during the rearrangement. The irradiation of 3,5-dimethyl-4-pyrone in sulfuric acid led to the isolation of a new intermediate, the cyclic sulfate 22, which in sulfuric acid is converted thermally or photochemically to the 2-pyrone 8. In aqueous sulfuric acid, 2-acylfurans are also found as irradiation products. It is concluded that the excited 4-hydroxypyrylium cations relax to hydroxyoxabicyclohexenyl cations (30) as primary ground-state intermediates. A minor pathway of isomerization via a P8 permutation pattern is also discussed. The photointcrconversion of 2-hydroxypyrylium cations (e.g., eq 8) is shown to occur by a P8 permutation pattern.

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Unstable intermediates

Abstract: The preparation of solutions thought to contain simple aliphatic carbonium ions is described and their spectra recorded. Alternative explanations are considered, and the nature of the electronic transition is discussed.

Cited by 24 publications

References 23 publications

Electronic Spectra of Organolithium Compounds

Electronic Spectra of Organolithium Compounds

Thermal Degradation and Bimolecular Decomposition of 2-Ethoxyethanol in Binary Ethanol and Isobutanol Solvent Mixtures: A Computational Mechanistic Study

Heterocyclic photochemistry. 1. Phototranspositions in hydroxypyrylium cations. Permutation pattern analysis and mechanistic studies

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