DIBENZO-18-CROWN-6 POLYETHER

MACROCYCLIC POLYETHERS DIBENZO-18-CROWN-6 POLYETHER AND DICYCL0HEXYL-18-CR0WN-6 POLYETHER... 

This product, tan fibrous crystals melting at 161-162°, amounts to 221-260 g. (39-48%) and is sufficiently pure for use in the next part of this preparation. The product may be purified further by recrystallization from benzene. The dibenzo-18-crown-6 polyether separates as white fibrous needles melting at 162.5-163.5° (Note 6). 

This residue is a mixture of stereoisomerio dicyclohexyl-18-crown-6 polyethers which may be contaminated with some unchanged dibenzo-18-crown-6 polyether and with alcohols arising from hydrogenolysis of the polyether ring. The submitter reports that this residue is sufficiently pure for many purposes such as the preparation of complexes with potassium hydroxide which are soluble in aromatic hydrocarbons. 

The preparation of dibenzo-18-crown-6 polyether directly from catechol and bis(2-chloroethyl) ether has been reported previously. The present procedure is an improvement of this method. Although dibenzo-18-crown-6 polyether can be obtained in 80% yield from bis-[2-(o-hydroxyphenoxy)-ethyl] ether and bis(2-chloroethyl) ether, the former intermediate has to be synthesized by a method involving several steps. One of the hydroxyl groups of catechol must be protected against alkali by reaction with a molecule of dihydropyran or chloromethylm ethyl ether. Then the intermediate is treated with bis(2-chloroethyl) ether in the presence of alkali and, finally, converted into the desired intermediate by acid hydrolysis. The yield of bis[2-(o-hydroxyphenoxy)-ethyl] ether was less than 40% so that the overall yield of dibenzo-18-crown-6 polyether never approached 39-48%, the yield of the present direct method. 

The physical properties of many macrocyclic polyethers and their salt complexes have been already described. - Dibenzo-18-crown-6 polyether is useful for the preparation of sharpmelting salt complexes. Dicyclohexyl-18-crown-6 polyether has the convenient property of solubilizing sodium and potassium salts in aprotic solvents, as exemplified by the formation of a toluene solution of the potassium hydroxide complex (Note 13). Crystals of potassium permanganate, potassium Lbutoxide, and potassium palladium(II) tetrachloride (PdClj + KCl) can be made to dissolve in liquid aromatic hydrocarbons merely by adding dicyclohexyl-18-crown-6 polyether. The solubilizing power of the saturated macrocyclic polyethers permits ionic reactions to occur in aprotic media. It is expected that this [)ropcrty will find practical use in catalysis, enhancement of... 

DIAZOMETHANE, BIS(TRIFLUORO-METHYL)-, 50, 6 Diazomethane, dideuterio-, 53, 38 2-DIAZOPROPANE, 50, 5, 27 DIBENZO-18-CROWN-6 POLYETHER, 52, 66... 

Pedersen, C.J. Macrocyclic polyethers. Dibenzo-18-crown-6 polyether and dicyclohexyl-18-crown-6 polyether. Org. Synth. 1972, 52. 66-74. 

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