A process for alkylating an aromatic compound comprising reacting at least one aromatic compound with a mixture of olefins selected from olefins having from about 8 to about 100 carbon atoms, in the presence of an acidic ionic liquid catalyst, wherein the resulting product comprises at least about 50 weight percent of a 1, 2, 4 tri-substituted aromatic compound or a 1, 2, 3 tri-substituted aromatic compound or mixtures thereof.