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Benzene is an organic chemical compound with the molecular formula C 6 H 6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.
Line bond structure of benzene [5] Electron flow through p orbitals showing the aromatic nature of benzene [5] Benzene, C 6 H 6, is the least complex aromatic hydrocarbon, and it was the first one defined as such. [6] Its bonding nature was first recognized independently by Joseph Loschmidt and August Kekulé in the 19th century. [6]
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.
Benzene is one of the best-known aromatic compounds as it is one of the simplest and most stable aromatics. Aromatic hydrocarbons contain conjugated double bonds. This means that every carbon atom in the ring is sp2 hybridized, allowing for added stability.
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 and physical properties.
Aromatic rings such as benzene may be written in one of three forms: In Kekulé form with alternating single and double bonds, e.g. C1=CC=CC=C1, Using the aromatic bond symbol :, e.g. C:1:C:C:C:C:C1, or; Most commonly, by writing the constituent B, C, N, O, P and S atoms in lower-case forms b, c, n, o, p and s, respectively.
Hückel's rule can also be applied to molecules containing other atoms such as nitrogen or oxygen. For example pyridine (C 5 H 5 N) has a ring structure similar to benzene, except that one -CH- group is replaced by a nitrogen atom with no hydrogen. There are still six π electrons and the pyridine molecule is also aromatic and known for its ...
The Hückel method or Hückel molecular orbital theory, proposed by Erich Hückel in 1930, is a simple method for calculating molecular orbitals as linear combinations of atomic orbitals. The theory predicts the molecular orbitals for π-electrons in π-delocalized molecules, such as ethylene, benzene, butadiene, and pyridine.