The use of zeolites for the isopropylation of toluene with propene or 2-propanol has been explored [2-7]. Selected results are shown in Table 6.1. Alkylation of toluene with 2-propanol at 520 K over H-beta, H-mordenite, H-ZSM-12 and H-Y gave cymenes selectively [2-5]. No appreciable enrichment in para isomer of cymenes was observed. On the other hand, over H-ZSM-5, high para-selectivity can be reached. However, n-propyltoluenes are always formed as a side product in non-negligible amounts [2, 5]. In contrast, a very high selectivity for p-cymene (94%) was observed over ZSM-5 modified with H3PO4, which was loaded only on its internal surface [6]. n-Propyltoluenes are not produced over the modified ZSM-5 [6].