Two phases of C(9)H(12)O(4): why is the structure at 295 K so complicated?

Laura L Duncan1, Brian O Patrick, Carolyn Pratt Brock

  • 1Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA.

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The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
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Adolf von Baeyer attempted to explain the instabilities of small and large cycloalkane rings using the concept of angle strain — the strain caused by the deviation of bond angles from the ideal 109.5° tetrahedral value for sp3  hybridized carbons. However, while cyclopropane and cyclobutane are strained, as expected from their highly compressed bond angles, cyclopentane is more strained than predicted, and cyclohexane is virtually strain-free. Hence, Baeyer’s theory that was based on the...
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¹H NMR: Complex Splitting

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