Synthesis and phase‐transfer catalytic activity of crown ethers bound to microporous polystyrene resins by oxyethylene spacers

Abstract

Crown ethers bound to microporous polystyrene resins by oxyethylene spacers were prepared by the reaction of monoazacrown ethers with 2‐tosyloxyethoxymethylated or 2‐(2‐tosyloxyethoxy)ethoxymethylated polystyrene resins crosslinked with 2 mol % of divinylbenzene. The activity of the immobilized lariat crowns for halogen exchange reactions under triphase conditions has been studied as a function of catalyst structure, loading, substrate structure, reagent structure, and solvent. The lariat catalysts with extra oxygen donors in the spacer chain exhibited higher activity than the corresponding immobilized catalysts without the donors in the spacer. The increased activity of the catalyst containing 15‐crown‐5 unit and two extra donors for the reaction of 1‐bromooctane with KI was concluded to result from the enhanced complexation with the K+ ion, induced by the cooperative coordination of the crown unit donors and the donors in the spacer chain. The recovered catalysts could be re‐used without decrease in activity.

Synthesis of a Novel Class of Azacrown Macrocycles and Lariat Crown Ethers Containing Two 1,2,4-Triazole Rings as Subunits

“…Lariat ethers have been designed as cation complexing agents which exhibit complexation behavior similar to crown ethers, but with a three-dimensional binding character. 10,11 Also, as efficient organic ligands, lariat crown ethers meet the requirement of rapid, strong, and three-dimensional cation binding, and can mimic the properties of natural ionophores. 12 In connection with these findings, and in a continuation of our interest in synthesizing macrocyclic crown compounds containing heterocyclic moieties, 13 we report here the synthesis of a series of 18-21-membered azacrown macrocycles fused with two 1,2,4-triazole rings, containing N and O inside the macrocyclic ring as donor atoms and possessing pendent thiol groups as precursors for the synthesis of lariat thioether macrocycles.…”

Insoluble Phase-Transfer Catalysts

“…When the spacer chain also contains complexable ether oxygen atoms, using 15-crown-5 as the PTC functional group, catalyst activity is even greater, as observed in halide exchange of KI with I-bromooctane [83].…”

A Novel Synthesis and Characterisation of Poly{1-[4-(Benzo-9-Crown-3-4″-Ylaminosulfonyl)Phenyl]Ethylene} as Phase Transfer Catalyst

“…4,5 It has been suggested that polystyrene containing crown ethers and mono azacrown ethers were used as phase-transfer catalysts for dehydrohalogenation, addition and substitution reaction and other organic reaction. 6 The major advantages of the polymer-supported phase transfer catalyst [7][8][9][10] are: (1) ease of separation from reaction mixture by filtration; and (2) recycling of the catalyst. This paper describes the synthesis of such polymeric crown ether by direct in this new method.…”