Alkylations of a-methylnaphthalene with long-chain olefins in the presence of various synthesized novel ionic liquids have been investigated. The effects of various parameters such as types of cation and anion of ionic liquids, molar fraction of anhydrous aluminum trichloride on the alkylations were studied. It is found that the alkylpyridinium bromochloroaluminate ionic liquids, especially butylpyridinium bromochloroaluminate (0.71-0.75 molar fraction of aluminum trichloride) indicated excellent catalytic performance for long-chain alkylations of alpha-methylnaphthalene. It is also found that the anions determine, to a large extent, both physical and chemical properties of ionic liquids, but organic cations mainly influence physical properties, and only have a slight impact on the catalytic performance, Moreover. the effects of type and dosage of transition metal in the modified ionic liquids on the catalytic performances were also investigated. For the less expensive reagents and the easier synthesis process, the Cu2+ modified butylpyridinium bromochloroaluminate ionic liquid could be a practical catalyst for alkylations of alpha-methylnaphthalene with long-chain olefins. (c) 2005 Elsevier B.V. All rights reserved.