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Issue 8, 1983
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The molecular structure of allenes and ketenes. Part 16. Phenyl carbon chemical shifts of γ-substituted phenylallenes as a probe for the transmissions of substituent effects across the allenic system

Abstract

13 C Chemical shifts of γ-substituted phenylallenes PhHC[double bond, length half m-dash]C[double bond, length half m-dash]CHX have been measured. In order to investigate how substituent effects are transmitted across the allenic system emphasis is on the 13C chemical shifts of the phenyl site. Analysis of the data using the dual substituent parameter approach reveals that inductive effects (polarizations) originating from the substituents' dipole moments are predominant. For the phenyl ipso-atom, however, delocalization effects are non-negligible. In order to account for the observations several types of ‘hyperconjugative interactions’ are discussed. Semiempirical CNDO/S molecular orbital calculations are used to inquire further into the electron density distributions of phenylallenes and into the modes of the transmissions of substituent effects across the allenic system. Electron density distributions of phenylallenes turn out to be significantly affected through hyperconjugation.

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Article type: Paper
DOI: 10.1039/P29830001093
J. Chem. Soc., Perkin Trans. 2, 1983, 1093-1101

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    The molecular structure of allenes and ketenes. Part 16. Phenyl carbon chemical shifts of γ-substituted phenylallenes as a probe for the transmissions of substituent effects across the allenic system

    C. J. Elsevier, J. Meijer, G. Tadema, P. Vermeer and W. Runge, J. Chem. Soc., Perkin Trans. 2, 1983, 1093
    DOI: 10.1039/P29830001093

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