enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Cyclohexane conformation - Wikipedia

    en.wikipedia.org/wiki/Cyclohexane_conformation

    Cis-1,4-Di-tert-butylcyclohexane has an axial tert-butyl group in the chair conformation and conversion to the twist-boat conformation places both groups in more favorable equatorial positions. As a result, the twist-boat conformation is more stable by 0.47 kJ/mol (0.11 kcal/mol) at 125 K (−148 °C) as measured by NMR spectroscopy. [9]

  3. Ring flip - Wikipedia

    en.wikipedia.org/wiki/Ring_flip

    The chair conformation minimizes both angle strain and torsional strain by having all carbon-carbon bonds at 110.9° and all hydrogens staggered from one another. [2] The conformational changes that occur in a cyclohexane ring flip take place over several stages. Structure D (10.8 kcal/mol) is the highest energy transition state of the process.

  4. Rotamers - Wikipedia

    en.wikipedia.org/wiki/Rotamers

    The repulsion between an axial t-butyl group and hydrogen atoms in the 1,3-diaxial position is so strong that the cyclohexane ring will revert to a twisted boat conformation. The strain in cyclic structures is usually characterized by deviations from ideal bond angles ( Baeyer strain ), ideal torsional angles ( Pitzer strain ) or transannular ...

  5. File:Cyclohexane ring flip and relative conformation energies ...

    en.wikipedia.org/wiki/File:Cyclohexane_ring_flip...

    A is thus the most stable conformation &, of all the other conformations, occurs most often in room temperature. Valleys A & B are local energy minima & A is global minima. A & B can thus be classified as conformers.

  6. Fürst-Plattner Rule - Wikipedia

    en.wikipedia.org/wiki/Fürst-Plattner_Rule

    Nucleophilic ring-opening of this class of epoxides can occur by an attack at either the C1 or C2-position. It is well known that nucleophilic ring-opening reactions of these substrates can proceed with excellent regioselectivity. The Fürst-Plattner rule attributes this regiochemical control to a large preference for the reaction pathway that ...

  7. Cyclohexane - Wikipedia

    en.wikipedia.org/wiki/Cyclohexane

    The chair and twist-boat are energy minima and are therefore conformers, while the half-chair and the boat are transition states and represent energy maxima. The idea that the chair conformation is the most stable structure for cyclohexane was first proposed as early as 1890 by Hermann Sachse, but only gained widespread acceptance much later.

  8. File:Cyclohexane ring flip.svg - Wikipedia

    en.wikipedia.org/wiki/File:Cyclohexane_ring_flip.svg

    4: boat When ring flip happens completely from chair-to-chair, hydrogens that were previously axial (blue H) turn equatorial & equatorial ones (red H) turn axial. Pink and orange arrows show how one can imagine how carbons are being "pushed" as one conformation turns into another. Source for the conformation names & claim of lowest/highest energy:

  9. Twistane - Wikipedia

    en.wikipedia.org/wiki/Twistane

    Twistane (IUPAC name: tricyclo[4.4.0.0 3,8]decane [2]) is an organic compound with the formula C 10 H 16. [3] It is a cycloalkane and an isomer of the simplest diamondoid, adamantane, and like adamantane, is not very volatile. Twistane was named for the way its rings are permanently forced into the cyclohexane conformation known as the "twist ...