Processes for the disproportionation and isomerization of a hydrocarbon feed using a liquid catalyst comprising an ionic liquid and a carbocation promoter are described. The ionic liquid is unsupported, and the reactions occur at temperatures below the decomposition temperature of the ionic liquid, typically below about 250° C. The process includes isomerizing a hydrocarbon feed comprising normal C6 alkane or branched C6 alkane by contacting the hydrocarbon feed with a liquid catalyst in a reaction zone to form a product mixture. Isomerization reaction mixtures are also described.