All organic compounds are classified as either aliphatic or aromatic. Aliphatic molecules are those that contain carbon chains with single and possibly double bonds. Aromatic compounds demonstrate properties that make them particularly special. Because of their structure, aromatics are stable and only undergo specific reactions. Benzene, shown below, is the most common aromatic compound.
There is a specific set of criteria by which a molecule must meet to be considered aromatic.
· They are found in a ring structure that is in a circular pattern with alternating double bonds. This property identifies them as cyclic molecules.
· They are planar, which means they can be drawn in a single plan dimension.
· Aromatic compounds also have conjugated double bonds, meaning the electrons surrounding the double bonds overlap those found on nearby adjacent atoms.
· They must also obey Hϋckles Rule, which states that that all the bonding orbitals must be full. An equation used to determine this is 4n+2, with n being a positive integer. Benzene for example has 3 π bonds, and therefore 6 π electrons ,(2 electrons per bond), the equation is written as
4n+2 = 6
n =1
Since n = 1 = positive, the rule is satisfied and thus the compound, in this case benzene, is indeed aromatic.
