Search results
Results from the WOW.Com Content Network
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 ...
when a ring with a circle is adjacent to a ring with two double bonds, an arrow is drawn from the former to the latter ring. Some results from these rules are worth being made explicit. Following Clar, [ 1 ] rules 1 and 2 imply that circles can never be in adjacent rings.
Every atom in the ring must have an occupied p orbital, which overlaps with p orbitals on either side (completely conjugated). Molecule must be planar. It must contain an odd number of pairs of pi electrons; must satisfy Hückel's rule: (4n+2) pi electrons, where n is an integer starting at zero.
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 ...
The theory predicts the molecular orbitals for π-electrons in π-delocalized molecules, such as ethylene, benzene, butadiene, and pyridine. [ 1 ] [ 2 ] [ 3 ] It provides the theoretical basis for Hückel's rule that cyclic, planar molecules or ions with 4 n + 2 {\displaystyle 4n+2} π-electrons are aromatic .
[2] [3] [4] This is usually considered to be because electrons are free to cycle around circular arrangements of atoms that are alternately single- and double-bonded to one another. This commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds ...
Since one of the most commonly encountered aromatic systems of compounds in organic chemistry is based on derivatives of the prototypical aromatic compound benzene (an aromatic hydrocarbon common in petroleum and its distillates), the word “aromatic” is occasionally used to refer informally to benzene derivatives, and this is how it was ...
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.