Toluene methyl group dehydrogenation

Because much toluene is demethylated for use as benzene, considerable effort has been expended on developing processes in which toluene can be used in place of benzene to make directiy from toluene the same products that are derived from benzene. Such processes both save the cost of demethylation and utilize the methyl group already on toluene. Most of this effort has been directed toward manufacture of styrene. An alternative approach is the manufacture of i ra-methylstyrene by selective ethylation of toluene, followed by dehydrogenation. Resins from this monomer are expected to displace... 

The Diels-Alder reaction between 3-(2-nitroethenyl)indole (229) and methyl 3-nitroacrylate (230) in the presence of aluminum chloride in boiling toluene was shown to lead to the formation of both the nitro carbazole species 233 and 235, in very low yield (8%, 1 10), and the corresponding compounds without the nitro group, 234 and 236 (25%, 10 1) [90]. The reaction was presumed to proceed via the cycloaddition adducts 231 and 232 (34%, 3 2), followed by dehydrogenation and denitration (Scheme 51). 

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