[74] The preparation and identification of 5-dehydroquinic and 5-dehydroshikimic acids

Publisher Summary This chapter describes the preparation and identification of 5-dehydroquinic and 5-dehydroshikimic acids. 5-Dehydroquinic and 5-dehydroshikimic acids can be prepared by the nitric acid oxidation of quinic acid. A more convenient procedure for the preparation of 5-dehydroquinic acid is, however, the platinum-catalyzed dehydrogenation of quinic acid and the stereospecificity of this reaction is dependent on quinic acid existing predominantly in a conformation in which the 5-dehydroxyl group is axially disposed. Quinic acid is dissolved in water and the pH is adjusted to 6.0 with solid sodium bicarbonate. It is observed that platinum oxide is placed in a hydrogenation flask, covered with water, and shaken with hydrogen at atmospheric pressure until the uptake of hydrogen ceases. Shikimic acid is recovered as a crystalline solid by concentration of the appropriate fractions. An important factor in this oxidation is the degree of dispersion of the platinum, because finely colloidal platinum is the best catalyst if it is freshly prepared.