CHM247H1 Chapter Notes - Chapter 15: Phenyl Group, Benzene, Substituent
Document Summary
Benzene and aromaticity: aromatic substances differ from others in their chemical behaviour, aromaticity: the special characteristics of cyclic conjugated molecules, including unusual stability and a tendency to undergo substitution rather than addition reactions on treatment with electrophiles. Aromatic molecules are planar, cyclic, conjugated species with 4n+2 electrons. This gives benzene a lot of stability from resonance. Delocalization of the electrons leads to an increase in energy: only aromatic if planar, monocyclic conjugated system, that contains 4n+2 electrons, where n is an integer. 15. 4 aromatic ions: carbon can be charged so that it represents 2 electrons (- charge) or 0 electrons (+ charge) or 1 electron (carbon radical). These electrons contribute to the p orbitals and therefore can be considered aromatic: ways in preparing involve removing a hydrogen with 2, 1 or no electrons. Infrared spectroscopy: characteristic stretching at 3030 cm-1 and a series of peaks in 1450-1600 cm-1.
