Benzene rings ( Aromatic Structures )
Aromatic compounds are so named because in the early days of carbon chemistry, fragrant structures turned out often to have benzene rings.
Benzene itself was isolated by Michael Faraday in 1825.
Studies of the structure using X Rays, show it has a very unusual structure, quite unlike most cyclic carbon compounds.
It is a flat structure whereas cyclic compounds are usually bent due to the tetrahedron bonding. The reason for this is, again, due to quantum mechanical reasons. The electrons "smear" around the ring forming a "hybridisation."
The analysis of molecules using X-Rays was initiated by physicists Sir William Bragg, his son Sir Lawrence Bragg and Max von Laue. The process involves crystalising the molecules and passing monochromatic X-Rays through the crystal from different directions. Interference patterns are created due to the separate planes of crystals and unique diffraction patterns are produced. The patterns are then use to recreate both the crystal and molecular structure. The technique is still very much used to analyse proteins and other molecules and was essential to the discovery of the structure of DNA.
