Cyclohexyl-18-crown

Cyclohexyl[l 5]crown-5, potassium complex equilibrium constant, 7, 742 (73MI52101) Cyclohexyl[15]crown-5, sodium complex equilibrium constant, 7, 742 (73MI52101) Cycloocta[ 1,2-c 5,6-c ]difuran H NMR. 4. 564 (70JA973) Cyclopenta[h][2.2.4]cyclazine... 

Frensdorff (3) has determined log K values for the reaction in methanol of several cyclic polyethers of varying ring size and numbers of donor atoms with Na+, K+, and Cs+ (all chlorides). The log K values are plotted in Fig. 2 where several trends are evident. The relationship between ring size and cation size which has been referred to as the selectivity order changes from Na+>K+ for dicyclohexyl-14-crown-4 to Na+ K+>Cs+ for cyclohexyl-15-crown-5, to K+ >Cs+ Na+ for dibenzo-... 

The ligands (15-crown-5) (78,83,85) and cyclohexyl(15-crown-5) 81) are both reported to give complexes of composition ULCI3, and a hy-... 

Figure 3.29 Variation of binding constant as a function cation radius for cyclohexyl crown ethers.

Crown ethers have particularly large complexing constants for alkali metals equilibrium constants for cyclohexyl-crown-6, for example, are in the order K+ > Rb+ > Cs+ > Na+ > Li+. The cryptates have high complexing ability especially for M2+ ions and will render even BaS04 soluble. They also have good complexing ability for transition metal ions (e.g., for lanthanides). 

Figure 1. Dependence of butyl acrylate percent conversion to polymer on the stability constants for potassium ion complexation in methanol of the various crown ethers. Line calculated by regression analysis o, experimental values 1, 18-crown-6 2, dicyclohexyl-18-crown-6 3, 21-crown-7 4, dibenzo-18-crown-6 5, 15-crown-5 6, cyclohexyl-1 5-crown-5 8, 1,10-diaza-18-crown-6. Reproduced from Ref. 2. Copyright 1981, American Chemical Society.

Acetylacetonato Trithio-benzo [9] crown-3 Hexathio-dibenzof 18]crown-6 Carbon monoxide dehydrogenase Coenzyme A Cyclopentadienyl Cyclic voltammetry Cyclohexyl... 

Ethers with from 3 to 20 oxygen atoms have been synthesized. The hydrogenated derivative of dibenzo-18-crown-6 is formally 2,5,8,15,18,21-hexaoxatri-cyclo[20.4.0.0]-hexacosane but usually is called cyclohexyl-18-crown-6. A general abbreviation is n-C-m where n is the ring size and m is the number of O atoms, for example, 18-C-6. 

Alcohol inversion. Elimination competes with S, 2 substitution in the inversion of secondary alcohols by the Mitsunobu reaction or by reaction of mesylates with cesium propionate or cesium acetate. Elimination in the inversion of cyclopentyl and cyclohexyl alcohols can be largely suppressed by reaction of the mesylate with cesium acetate (excess) and a catalytic amount of l8-crown-6 in refluxing benzene. Even inversion of an ally lie alcohol can be effected in moderate yield under these conditions (equation I). ... 

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