Potassium hydroxide as a promoter for the potassium-metal catalyzed side-chain alkylation of toluene

Article abstract of DOI:10.1016/0022-328X(90)80211-H

Potassium hydroxide acts synergistically with catalyst supports such as alumina, diatomaceous earth, or potassium carbonate to promote the potassium-metal catalyzed side-chain alkylation of toluene with propene.Carrying out the reaction with wet toluene to generate KOH in situ is a particularly effective method for promoting the reaction.The catalyst supports are not inert in the absence of the promoter, because they alter alkylation regiochemistry and increase the formation of methylindan by-products.As a mechanistic probe, the amounts of benzylpotassium that formare compared with propylation reaction rates.This is the first report concerning the amount of benzylpotassium that forms under side-chain alkylation conditions.From this and other data, a previously unrecognized mechanism for the promotion of side-chain alkylation is identified.