Alkenes to aryl alkanes:

The reaction of an aromatic ring like benzene with an alkene within acid conditions results in the creation of an aryl alkane.

Figure: Synthesis of arylalkanes from alkenes.

As far as the alkene is considered this is other example of electrophilic addition including the addition of a proton to one end of the double bond and the addition of the aromatic ring to another. As far as the aromatic ring is considered this is an instance of an electrophilic substitution reaction termed as the Friedel-Crafts alkylation.