1,4-Cyclohexanediol, separation

In 1994, Hanessian and co-workers [50] reported the first examples of metal-free three-dimensional triple-stranded helicates through spontaneous self-assembly of chiral C2-symmetrical diols and chiral C2-symmetrical diamines. The initial observation resulted from the utilization of enantiopure C2-symmetrical vicinal trans-1,2-diaminocyclohexane [51,52] as ligands in the asymmetric dihydroxylations of olefins [53] and as reagents for asymmetric synthesis [54], When equimolar amounts of (5,5)-frfl x-l,2-diaminocyclohexane (28) and its (i ,i )-enantiomer (29) were individually mixed with (5,5)-frfl x-l,2-cyclohexanediol and heated in refluxing benzene, crystals of the respective supraminol complexes 28 30 and 29 30 were formed quantitatively (Scheme 12). This was the physical basis for the separation of racemic diols with tr[Pg.104]

Figure 21.10 CC chromatogram showing the separation of enantiomeric sec-phenethyl alcohol, 1-phenyl-1-butanol, and trans-l,2-cyclohexanediol. Chromatographic conditions fused-silica capillary column (8m, 250pm ID) coated with (lS,2R)-(H-)-N,N-dimethylephedrinium-...

Investigate the effect of changing the ratios of the two solvents used for the separation of the 1,2-cyclohexanediols on the f /-values for the diastereomers. One way to report the relative effeotiveness of various solvent mixtures in effeoting the separation would be to report values of AR for each mixture used. Consult with your instructor before carrying out any experiments. 

In a separate study (324), the Baiker group reports a similar study on the amination of 1,4-cyclohexanediol in scNHs using this Co-Fe catalyst. Di-aminocyclohexanes are typically manufactured by the catalytic hydrogenation of aromatic amines such as p-phenylenediamine (324), so that direct amination of cyclohexanediols provides an attractive process alternative. Operation of a... 

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