http://www.ck12.org Chapter 25. Organic Chemistry
FIGURE 25.15
An alternate system for naming di-substituted benzene rings uses three different prefixes:ortho,meta, andpara. If
two groups areorthoto one another, they are on adjacent carbon atoms.Metapositioning refers to a 1,3 arrangement,
andparasubstituents are in a 1,4 arrangement. Shown below are the three possibilities for dimethylbenzene.
Lastly, a benzene ring missing one hydrogen atom (−C 6 H 5 ) can itself be considered the substituent on a longer chain
of carbon atoms. That group is called aphenylgroup, so the molecule below is called 2-phenylbutane.