MICROCOMPUTER-AUTOMATED REACTOR FOR SYNTHESIS OF C-13-LABELED MONOSACCHARIDES

For less labor-intensive, larger-scale, and more efficient production of D-[1-C-13]glucose and other labeled monosaccharides using the cyanohydrin reduction reaction, an automated reactor was designed, constructed, and tested. A suitable vessel and all ancillary and control equipment were fabricated, or otherwise obtained, and the apparatus was controlled with a microcomputer program written in BASIC. Running without manual intervention, the yields for the condensation reaction of D-arabinose with KCN and the recovery of the excess cyanide were high (> 90%), and the resultant aldononitriles were reduced to product aldoses with little reduction of the intermediate imines to amines. The reduction rate could be improved by controlling pH between 2-4 and by agitation speeds > 250 rpm, while no improvement resulted from the use of high hydrogen pressures [ > 129 kPa (4 psig)]. Reduction reactions conducted in the presence of formic acid (to regulate pH) suggest that formic acid acted as a coreducing agent.