Reaction of olefins with aluminium chloride stabilized arene-mercury complexes

Article type: Research Article

Authors: Borovik, Alexander S. | Barron, Andrew R.

Affiliations: Department of Chemistry, Rice University, Houston, Texas 77005

Note: [] Corresponding author. E-mail: arb@rice.edu

Abstract: Mercury-arene complexes, [Hg(arene)2(AlCl4)2], are found to be active catalysts for the alkylation of arenes with olefins. Ethylene, propylene, and cyclohexylene react with benzene, toluene or ethylbenzene to form mono- or polyalkylated products, the distribution being dependent on the nature of the alkene. Deuterium labeling experiments using C6D6 show that deuterium is exclusively attached to the primary carbon atom of the resulting alkyl substituent leading to the proposal that the alkylation reaction occurs via the insertion of an olefin into a Hg–Car σ bond formed from the reaction of [Hg(arene)2(AlCl4)2] with arene solvent. The limiting factor in controlling the yield of the alkylation reaction is the preferential binding of the polyalkyl-arene products to the mercury. The lack of equivalent reaction for either AlCl3 or HgCl2 alone suggests that the ‘indirect activation’ of a weak Lewis acid (HgCl2) by the coordination of a strong Lewis acid (AlCl3).

Keywords: Aluminium, Mercury, Olefin, Arene, Deuterium, Indirect activation

DOI: 10.1080/10241220500296951

Journal: Main Group Chemistry, vol. 4, no. 2, pp. 135-144, 2005