Why shape of Aromatic compounds are hexagonal ?
2006-08-17 07:10:14 · 5 answers · asked by star123 2 in Science & Mathematics ➔ Chemistry
Aromatic compunds do not have to be hexagonal. The condition for aromatic compounds is that these compunds must be cyclic, with 4n + 2 conjugated pi electrons. Furthermore, the unhybridized p orbitals must overlap to form a continuous ring of parallel orbitals, and delocalization of the pi electrons over the ring must lower the electronic energy. The 4n + 2 rule can be derived from molecular orbital theory. If you recall the pattern of molecular orbitals (MOs) in a cyclic conjugated system, there is one all-bonding, lowest-lying MO, followed by degenerate pairs of bonding MOs. The lowest lying MO is always filled with two electrons, and each additional shell consists of two degenerate MOs, requiring four electrons to fill a shell. A compound has a filled shell of orbitals if it has two electrons for the lowest lying orbital, plus 4n electrons, where n is the number of filled pairs of degenerate orbitals. Compunds with all the shells filled are extremely stable, and are called aromatic. Examples of aromatic compounds include cyclopropenyl cation (triangular),
pyrrole (pentagonal) and indole (a ten pi-electron system).
2006-08-17 07:37:30 · answer #1 · answered by prune 3 · 0⤊ 0⤋
Not all aromatic compounds, but benzene is a perfect hexagon. It's because the bonds are the same lenght, intermediate between that of a single and that of a double bond - if all bond lenghts are equal it's more stabe in the form of hexagon. The Ï-bonds are formed from overlap of atomic p-orbitals above and below the plane of the ring.
2006-08-17 14:22:14 · answer #2 · answered by Anonymous · 1⤊ 0⤋
Carbon forms rings of various sizes. The most stable is a six membered ring (hexagonal). Most aromatic compounds have what is called a benzene ring in them -- the benzene ring is a special six membered ring. The benzene ring has three double bonds that constantly shift to make it appear as if every carbon-carbon linkage in the ring has ~1½ bonds. It is very stable and our noses pick up the scent of these rings very well (hence the name aromatic).
2006-08-17 14:23:10 · answer #3 · answered by The Q 2 · 0⤊ 0⤋
Aromatic carbons usually contain a benzene ring, which is hexagonal. That is just the way the carbons are bonded together in benzene.
2006-08-17 14:19:27 · answer #4 · answered by Anonymous · 0⤊ 0⤋
na na...al d aromatic compounds are not hexagonal.
its just benzene is due to perfect bond-length n over-lapping of p-orbitals!!
2006-08-17 15:02:21 · answer #5 · answered by ani 2 · 0⤊ 0⤋