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  2. Clar's rule - Wikipedia

    en.wikipedia.org/wiki/Clar's_rule

    An aromatic π-sextet can be represented by a circle, as in the case of the anthracene molecule (below). Clar's rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. one with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical ...

  3. Anthracene - Wikipedia

    en.wikipedia.org/wiki/Anthracene

    Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C 14 H 10, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the production of the red dye alizarin and other dyes. Anthracene is colorless but exhibits a blue (400–500 nm peak) fluorescence under ultraviolet radiation. [13]

  4. Aromatic compound - Wikipedia

    en.wikipedia.org/wiki/Aromatic_compound

    Heteroarenes are aromatic compounds, where at least one methine or vinylene (-C= or -CH=CH-) group is replaced by a heteroatom: oxygen, nitrogen, or sulfur. [3] Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one ...

  5. Diels–Alder reaction - Wikipedia

    en.wikipedia.org/wiki/Diels–Alder_reaction

    Frontier molecular orbital theory has also been used to explain the regioselectivity patterns observed in Diels–Alder reactions of substituted systems. Calculation of the energy and orbital coefficients of the components' frontier orbitals [ 17 ] provides a picture that is in good accord with the more straightforward analysis of the ...

  6. 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 by the stabilization of conjugation alone.

  7. Organic semiconductor - Wikipedia

    en.wikipedia.org/wiki/Organic_semiconductor

    In the early days of fundamental research into organic semiconductors the prototypical materials were free-standing single crystals of the acene family, e.g. anthracene and tetracene. [21] The advantage of employing molecular crystals instead of amorphous film is that their charge carrier mobilities are much larger.

  8. Cell theory - Wikipedia

    en.wikipedia.org/wiki/Cell_theory

    From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...

  9. Simple aromatic ring - Wikipedia

    en.wikipedia.org/wiki/Simple_aromatic_ring

    Simple aromatic rings can be heterocyclic if they contain non-carbon ring atoms, for example, oxygen, nitrogen, or sulfur. They can be monocyclic as in benzene, bicyclic as in naphthalene, or polycyclic as in anthracene. Simple monocyclic aromatic rings are usually five-membered rings like pyrrole or six-membered rings like pyridine.