Selective fructose transport through supported liquid membranes containingdiboronic acid or conjugated monoboronic acid-quaternary ammonium carriers.

The design and preparation of two new classes of boronic acid carriers is d escribed along with an evaluation of their abilities to extract and transpo rt the commercially important sugars, fructose, glucose, and sucrose throug h polymer supported liquid membranes. Transport fluxes with diboronic acid carriers are lower than those observed with monoboronic acids. However, fru ctose selectivity is improved when the diboronic linker group allows the fo rmation of a 1:1 macrocyclic complex. A conjugated monoboronic acid-quatern ary ammonium carrier facilitates fructose transport about twenty times bett er than an analogous monoboronic acid/quaternary ammonium mixture. The rate -determining step for the transport is diffusion through the membrane. (C) 1999 Elsevier Science Ltd. All rights reserved.