Regulations for the Product Distribution of the Oxidative Coupling of p-Cresol by Cyclodextrins

Abstract

The oxidative coupling of p-cresol in the aqueous solution was carried out in the presence of cyclodextrins. The production of the dimeric compound was preferentially prevented by α-cyclodextrin, while the trimerization was efficiently inhibited by γ-cyclodextrin. The different effects of these two cyclodextrins were explained by their different inclusion complex forming ability which depended on their cavity size.

Biomimetic Reactions Catalyzed by Cyclodextrins and Their Derivatives

“…For example, an interesting alkylation of a hydroquinone is promoted modestly by binding into a cyclodextrin (Figure 7). 140 Also, there are many examples in which the point of reaction of an external reagent is influenced when a substrate binds into a cyclodextrin cavity [12][13][14][15][16][17][18][19][20][21][22][23][24][141][142][143][144] but so far with no evidence that the cyclodextrin catalyzes the process as it does in the HOCl chlorinations. The bromination of anisole and some phenols shows at most a slight acceleration by R-CD and is often retarded because tribromide ion binds into the cyclodextrin cavity.…”

“…For example, an interesting alkylation of a hydroquinone is promoted modestly by binding into a cyclodextrin (Figure ) . Also, there are many examples in which the point of reaction of an external reagent is influenced when a substrate binds into a cyclodextrin cavity − ,− but so far with no evidence that the cyclodextrin catalyzes the process as it does in the HOCl chlorinations. The bromination of anisole and some phenols shows at most a slight acceleration by α-CD and is often retarded because tribromide ion binds into the cyclodextrin cavity. , However, α-CD catalyzes the debromination of some bromocyclohexadienones (the proposed mechanism is shown in Figure ), the reverse of one of the steps in the bromination of aromatic rings. , α-CD also modestly catalyzes the reaction of formic acid with bromine …”