A vinyl halide is clearly a species with a formula #H_2C=C(X)H#, in which a halide is directly bound to an olefinic bond. Formally, this is ethylene, #H_2C=CH_2#, with one of the hydrogens substituted by a heteroatom. Vinyl chloride, #H_2C=CHCl# is an example. An aryl halide has general formula #C_6H_5X#, in which an halide group #X# has substituted the aryl ring. The simplest examples of an aryl halides are bromobenzene or chlorobenzene, #C_6H_5X#.
Of course, we often represent benzene with a formula of #"1,3,5-cyclohexatriene"#, but this is a representation rather than an actuality. In an aromatic ring, the #pi# electrons are conceived to be delocalized around the ring.
