Iron-containing graphite as a Friedel-Crafts alkylation catalyst

The activity of iron-containing graphites for the Friedel-Crafts reaction o f phenol with tert-butyl halides was studied. Graphites were characterized by XRD and XPS. The reaction of phenol with either various tert-butyl halid es or tert-butyl alcohol on iron-containing graphite was performed in a ben zene solvent for 4 h at 50 degreesC. The conversion and yield of the reacti on on iron-containing graphite decreased in the order, tert-butyl iodide, t ert-butyl bromide, and tert-butyl chloride, whereas for AlCl3, tert-butyl c hloride was the most reactive while tert-butyl iodide was the least. Activa ted charcoal was not reactive. The presence of iron accelerated the reactio n of phenol with the tert-butyl halide on graphite to yield p-tert-butylphe nol as the main product. The presence of both tert-butyl bromide and iron i ncreased the distance between the layers of graphite but not in the presenc e of either the iron or tert-butyl bromide. tert-Butyl halide was first ads orbed on graphite and then dissociated to form tert-butyl and halogen ions. The peak was observed at d = 11.9 Angstrom in the XRD pattern of the graph ite after the reaction in which the high purity graphite was treated with t ert-butyl halide and iron in phenol. This is probably due to the mixture of phenol with tert-butyl ion and iron inserted into the layers of graphite t o form a two-stage structure. (C) 2001 Academic Press.