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Updated: Aug 7, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
10:44

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

Strain-free sextet-resonant benzenoids and their antisextet dualists

Alexandru T Balaban1, Thomas G Schmalz

  • 1Texas A&M University at Galveston, 5007 Avenue U, Galveston, Texas 77551, USA. balabana@tamug.edu

Journal of Chemical Information and Modeling
|July 25, 2006
PubMed

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Structure of Benzene: Molecular Orbital Model

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Structure of Benzene: Kekulé Model

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Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm in the 1H NMR spectrum. The observed shift is far downfield because the aromatic ring current strongly deshields the protons. Any substitution on the benzene ring makes the aromatic protons nonequivalent, and the protons split each other. The peak is, therefore, no longer a singlet and the splitting pattern and their associated coupling constants depend...