A NEW POLYMER-BONDED β-CYCLODEXTRIN CATALYST FOR SELECTIVE SYNTHESIS OF 4-HYDROXYBENZOIC ACID
摘要
A new polymer-bonded cyclodextrinwas prepared from chloromethyluted styrene-divinylben-zene copolymer , sodium salt of cyclodertrin CD, KI,and (C1II9)4N+I- in a molar ratio of Cl:CD 1 =1:1.5:1. Element analyses showed that CD content in the above catalyst was 701 molg-1. With the polymer-bonded CD as catalyst , 4-hydroxybenzoic acid was synthesized at 97% selectivity and in 90mol% yield by the reaction of phenol and CCl4. Without the polymer catalyst, however, the selectivity was 56% and the yield was only 15mol%. The CD polymer was conveniently recovered from the reaction mixture by filtration and could be repeatedly used without notable decreases in catalytic activity, which indicated that the CD polymer compared to the free CDs or the CDs modified by small molecules has the unproved industrial applicability. Finally, A possible mechanism catalyzed by the polymer-bonded CD was also suggested on the basis of these results.