Proton Magnetic Resonance Studies of Ten Diolefins<sup>1a</sup>

Koster, David F.; Danti, Alfred

doi:10.1021/j100886a020

Cited by 35 publications

(11 citation statements)

References 5 publications

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“…they are related to (group) electronegativities or polarity effects [2,5,19]. In LCAO expansions for the descriptions of the electronic structures of planar unsaturated systems (ethylenes, benzenes, etc.)…”

Section: Discussion Of Substituent Effectsmentioning

confidence: 99%

“…The experimental coupling constants are partly from the literature [2][3][4][5][6][7][8][9][10] and partly from this series of contributions [1,11].…”

Section: Ht \ R/ Xmentioning

confidence: 99%

“…At first, using the material now being available, it is analyzed whether the coupling constants are additive in ligand-specific parameters as has been suggested in Ref. [5] on the basis of only two independent tests. For this purpose use is made of algebraic (geometrophysical) concepts which have been applied to the general treatments of various molecular properties of allenes [1,12].…”

Section: Ht \ R/ Xmentioning

confidence: 99%

“…This treatment is especially concerned with the relative importance of a and n mechanisms for the transmissions of substituent effects in monosubstituted allenes and, for instance, focusses attention to the question [5] tuents like Cl and CH3, which are apparently different with respect to their polar natures and (group) electronegativities, both reduce the (absolute) magnitudes of the four-bond proton-proton couplings in allenes.…”

Section: Ht \ R/ Xmentioning

confidence: 99%

“…It may be assumed that the experimental errors of the individual values do not exceed ± 0.07 Hz. Considering all the couplings in Table I the suggestion that the four-bond proton-proton couplings in allenes are additive in ligand-specific parameters [5] …”

Section: Nonadditivity Of Substituent Effects On the Four-bond Couplingsmentioning

confidence: 99%

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The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

Runge¹

1978

Zeitschrift Für Naturforschung B

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Abstract Four-bond proton-proton coupling constants in allenes are reported. The substituent effects on the coupling constants are discussed on the basis of the dual-substituent parameter approach. Furthermore, the coupling constants are related to quantum-chemical indices (electron densities, overlap populations) obtained from semiempirical CNDO/S and ab initio STO-3G calculations.The magnitudes of the coupling constants depend upon the polar natures of the substituents as well as upon their charge-transfer abilities (resonance effects) to a com-parable amount.In general, the coupling constants in 1,3-disubstituted allenes are nonadditive in ligand -specific parameters.

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Section: Discussion Of Substituent Effectsmentioning

confidence: 99%

“…The experimental coupling constants are partly from the literature [2][3][4][5][6][7][8][9][10] and partly from this series of contributions [1,11].…”

Section: Ht \ R/ Xmentioning

confidence: 99%

Section: Ht \ R/ Xmentioning

confidence: 99%

Section: Ht \ R/ Xmentioning

confidence: 99%

Section: Nonadditivity Of Substituent Effects On the Four-bond Couplingsmentioning

confidence: 99%

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The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

Runge¹

1978

Zeitschrift Für Naturforschung B

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Gas-Phase Kinetic and Mechanistic Studies of some Interconverting Alkylcyclopropene Pairs: Involvement of Dialkylvinylidene Intermediates and Their Quantitative Behaviour

Schulenburg¹,

Hopf²,

Walsh³

2000

Chem. Eur. J.

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The pyrolyses of two isomeric pairs of alkylcyclopropenes, namely 1,3-dimethyl-(15) and 1-ethyl-cyclopropene (16), and 1,3,3-trimethyl-(5) and 1-isopropyl-cyclopropene (17), have been studied in the gas phase. Complete product analyses at various conversions up to 95% were obtained for the decomposition of each compound at five temperatures over a 40 degrees C range. The time-evolution data showed that the isomerisation reactions 15<==>16 and 5<==>17 were occurring. Kinetic modelling of each system allowed the determination of rate constants for these and all other decomposition processes. Tests confirmed that all reactions were unimolecular and homogeneous. Arrhenius parameters are reported for overall reactions and individual product pathways. Further kinetic analysis allowed us to extract the propensities (at 500 K) for 1,3-C-H insertion of the dialkylvinylidene intermediates involved in the rearrangements as follows: k(prim):k(sec): k(tert)= 1:16.5:46.4. Additional experiments with 13C-labelled cyclopropenes yielded alkyl group migration aptitudes for the dialkylvinylidenes (from the pattern of 13C in the alkyne products) as follows: Me:Et:iPr=1:3.1:1.5. Explanations for these trends are given. Another important finding is that of the dramatic rate enhancements for 1,3-diene product formation from the 1-alkylcyclopropenes; this can be explained by either hyperconjugative stabilisation of the vinylcarbene intermediates involved in this pathway, or their differing propensities to 1,2 H-shift. The observed large variations in product distribution amongst these four cyclopropenes is interpreted in terms of these specific effects on individual pathways.

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Detection, determination and identification of allenes and ketenes

Munson

Ketenes, Allenes and Related Compounds: Vol. 1 (1980)

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Proton Magnetic Resonance Studies of Ten Diolefins^1a

Cited by 35 publications

References 5 publications

The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

Gas-Phase Kinetic and Mechanistic Studies of some Interconverting Alkylcyclopropene Pairs: Involvement of Dialkylvinylidene Intermediates and Their Quantitative Behaviour

Detection, determination and identification of allenes and ketenes

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Proton Magnetic Resonance Studies of Ten Diolefins1a

Cited by 35 publications

References 5 publications

The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

Gas-Phase Kinetic and Mechanistic Studies of some Interconverting Alkylcyclopropene Pairs: Involvement of Dialkylvinylidene Intermediates and Their Quantitative Behaviour

Detection, determination and identification of allenes and ketenes

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Product

Resources

About

Proton Magnetic Resonance Studies of Ten Diolefins^1a