ChemInform Abstract: STEREOCHEMICAL STUDIES. XX. CONFORMATIONS OF 1,2‐TRANS‐DISUBSTITUTED CYCLOHEXANES

Zefirov, N. S.; Gurvich, L. G.; Shashkov, A. S.; Krimer, M. Z.; Vorob'eva, E. A.

doi:10.1002/chin.197636063

Cited by 1 publication

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“…This preference for the diaxial conformer should allow for a higher-than-expected reactivity of these molecules toward E2 eliminations. Note that dihalogenated cyclohexanes − ,− ( trans -1,2-dihalocyclohexanes and trans -1,4-dihalocyclohexanes) show a significant solvent sensitivity of the equilibrium constant, unlike monosubstituted cyclohexanes.…”

Section: Resultsmentioning

confidence: 99%

London Dispersion Helps Refine Steric A-Values: The Halogens

2021

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Halogens are rarely considered as dispersion energy donors for organic reaction design. Here, we re-examine one of the textbook examples for assessing steric hindrance, the A-value, and demonstrate that even in this system, halogens cannot be treated solely as classic repulsive hard spheres. A significant part of the steric demand of the halogens is compensated by attractive London dispersion (LD) interactions, explaining the experimental lack of a clear trend when going down the halogens’ row. Beyond monohalogenated cyclohexanes, dihalo- and perhalocyclohexanes also show significant LD interactions. We also explored several other small organic systems containing halogens. Our findings show that organic chemists should treat halogens as possible sources of LD interactions in reaction design, as these atoms can change the landscape of the potential energy surface and reverse trends of conformer stabilities and reaction selectivities.

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