In acidic aqueous solutions the xylonic acid/xylonate equilibrium is coupled with the formation of the γ- and δ-lactones. The γ-lactone is formed more readily, whereas the δ-lactone can only be observed in traces at very low pH values (<2.5). By means of 13C NMR, both the lactone hydrolization constant and the acid dissociation constant could be determined (KL = 4.08, = 3.65 ± 0.34). Further, a second deprotonation of one of the hydroxyl groups could be observed at very high pH ( = 13.3 ± 0.76).
- Xylonic acid