The isomers differ in the location of the bromine, but have the same chemical formula.
Benzyl bromide is an isomer, which has a bromine substituted for one of the hydrogens of toluene's methyl group, and it is sometimes named α-bromotoluene.
A laboratory route to p-bromotoluene proceeds from p-toluidine, which is diazotiized followed by treatment with copper(I) bromide.
For example, the methyl group may be oxidized using potassium permanganate to form the corresponding bromobenzoic acid.
[5] The methyl group may also be partially oxidized to form bromobenzaldehyde.