The catalytic effect of a 2 : 1 complex between 3-deoxy-3-[N-(2-aminoethyl)] amino-β-cyclodextrin and Cu(II) on the oxidation of furoin, 1, 2-difuryl-2-oxoethanol, was examined at pH 1O.5 and 25 ℃.
The reaction was siginficantly accelerated by the complex. However, the magnitude of the increase was smaller than that by the corresponding 6-deoxy-6-[N-(2-aminoethyl)] amino-β-cyclodextrin complex. The existence of two β-cyclodextrin cavities in a complex molecule may be preferable for the rate acceleration to that of one cavity in a molecule.
This fact suggests that each cavity in the complex fixes each furil group in furoin to locate the reaction site of furoin in the vicinity of the Cu(II)ion. The rate acceleration may be caused by electrostatic stabilization of the enolate anion of furoin.