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  2. Cyclobutadiene - Wikipedia

    en.wikipedia.org/wiki/Cyclobutadiene

    The rectangular structure is consistent with the existence of two different 1,2-dideutero-1,3-cyclobutadiene valence isomers. This distortion indicates that the pi electrons are localized, in agreement with Hückel's rule which predicts that a π-system of 4 electrons is not aromatic. In principle, another situation is possible.

  3. Annulene - Wikipedia

    en.wikipedia.org/wiki/Annulene

    Using this form of nomenclature 1,3,5,7-cyclooctatetraene is [8]annulene and benzene is [6]annulene (and occasionally referred to as just 'annulene'). [ 2 ] [ 3 ] The discovery that [18]annulene possesses a number of key properties associated with other aromatic molecules was an important development in the understanding of aromaticity as a ...

  4. Cyclobutene - Wikipedia

    en.wikipedia.org/wiki/Cyclobutene

    The compound was first prepared by thermolysis of the ammonium salt [C 4 H 7 N(CH 3) 3]OH (cyclobutyltrimethylammonium hydroxide). [2] Cyclobutene thermally isomerizes to 1,3-butadiene. This strongly exothermic reaction reflects the dominance of ring strain. In contrast, the corresponding equilibrium for hexafluorocyclobutene disfavors ...

  5. Butalene - Wikipedia

    en.wikipedia.org/wiki/Butalene

    Butalene is a polycyclic hydrocarbon composed of two fused cyclobutadiene rings. [1] A reported possible synthesis of it involves an elimination reaction from a Dewar benzene derivative. The structure itself can be envisioned as benzene with an internal bridge, and calculations indicate it is somewhat less stable than the open 1,4 ...

  6. Homoaromaticity - Wikipedia

    en.wikipedia.org/wiki/Homoaromaticity

    Homoaromaticity, in organic chemistry, refers to a special case of aromaticity in which conjugation is interrupted by a single sp 3 hybridized carbon atom. Although this sp 3 center disrupts the continuous overlap of p-orbitals, traditionally thought to be a requirement for aromaticity, considerable thermodynamic stability and many of the spectroscopic, magnetic, and chemical properties ...

  7. Cycloalkene - Wikipedia

    en.wikipedia.org/wiki/Cycloalkene

    Cyclization reactions, or intramolecular addition reactions, can be used to form cycloalkenes. These reactions primarily form cyclopentenones, a cycloalkene that contains two functional groups: the cyclopentene and a ketone group. [12] However, other cycloalkenes, such as Cyclooctatetraene, can be formed as a result of this reaction. [11]

  8. Cyclooctatetraene - Wikipedia

    en.wikipedia.org/wiki/Cyclooctatetraene

    1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C 8 H 8. It is also known as [8] annulene . This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature.

  9. Butadiene - Wikipedia

    en.wikipedia.org/wiki/Butadiene

    That implies a stabilization energy of 3.5 kcal/mol. [25] Similarly, the hydrogenation of the terminal double bond of 1,4-pentadiene releases 30.1 kcal/mol of heat, while hydrogenation of the terminal double bond of conjugated (E)-1,3-pentadiene releases only 26.5 kcal/mol, implying a very similar value of 3.6 kcal/mol for the stabilization ...