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  2. Antiaromaticity - Wikipedia

    en.wikipedia.org/wiki/Antiaromaticity

    Unlike aromatic compounds, which follow Hückel's rule ([4n+2] π electrons) [1] and are highly stable, antiaromatic compounds are highly unstable and highly reactive. To avoid the instability of antiaromaticity, molecules may change shape, becoming non-planar and therefore breaking some of the π interactions.

  3. UNIFAC - Wikipedia

    en.wikipedia.org/wiki/UNIFAC

    The activity of a real chemical is a function of the thermodynamic state of the system, i.e. temperature and pressure. Equipped with the activity coefficients and a knowledge of the constituents and their relative amounts, phenomena such as phase separation and vapour-liquid equilibria can be calculated. UNIFAC attempts to be a general model ...

  4. Cyclobutadiene - Wikipedia

    en.wikipedia.org/wiki/Cyclobutadiene

    The compound is the prototypical antiaromatic hydrocarbon with 4 pi electrons (or π electrons). It is the smallest [n]-annulene ([4]-annulene).Its rectangular structure is the result of a pseudo [3] - (or second order) Jahn–Teller effect, which distorts the molecule and lowers its symmetry, converting the triplet to a singlet ground state. [4]

  5. Thiepine - Wikipedia

    en.wikipedia.org/wiki/Thiepine

    In organic chemistry, thiepine (or thiepin) is an unsaturated seven-membered heterocyclic compound, with six carbon atoms and one sulfur atom. The parent compound, C 6 H 6 S is unstable and is predicted to be antiaromatic.

  6. Category:Antiaromatic compounds - Wikipedia

    en.wikipedia.org/.../Category:Antiaromatic_compounds

    Pages in category "Antiaromatic compounds" The following 13 pages are in this category, out of 13 total. This list may not reflect recent changes. ...

  7. Cyclooctatetraene - Wikipedia

    en.wikipedia.org/wiki/Cyclooctatetraene

    Because COT is unstable and easily forms explosive organic peroxides, a small amount of hydroquinone is usually added to commercially available material. Testing for peroxides is advised when using a previously opened bottle; white crystals around the neck of the bottle may be composed of the peroxide, which may explode when mechanically disturbed.

  8. Aromaticity - Wikipedia

    en.wikipedia.org/wiki/Aromaticity

    Two different resonance forms of benzene (top) combine to produce an average structure (bottom). In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone.

  9. Thermodynamic activity - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_activity

    The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.