Figure 2.

2nprop undergoes deuterium exchange in neutral phosphate buffer. ¹H-NMR spectra are shown for 2nprop in D₂O (top) and D₂O/phosphate buffer pH 7.4 (bottom) kept at room temperature for 3 days. Top spectrum (taken in D₂O): the presence of three proton signals (a, b, c) as expected from 2nprop. Bottom spectrum: disappearance of the b proton signal, corresponding to the position occupied on the nitro-carrying β-carbon. Also, because the NMR medium was water (i.e., D₂O), hydrogen bonding and proton exchange eliminates the hydroxyl proton peak in this spectrum.