Kinetics of isotopic hydrogen exchange in 3-hydroxypyridine N-oxide

1. A study has been made of the effect of temperature on the pH of aqueous solutions of 3-hydroxypyridine N-oxide, working over the pH range from 1.0 to 9.5 and at temperatures in the 24–90‡C interval. 2. Equations describing the effect of temperature on the protonzation and ionization constants of aqueous solutions of 3-hydroxypyridine N-oxide have been developed. 3. Analysis of the kinetics of H/D exchange in 3-hydroxypyridine N-oxide at 160‡C and pD 1.0–9.5 showed electrophilic substitution at high pD to involve the D3O+ ion and the anion form of 3-hydroxypyridine N-oxide; at pD < 6 H/D exchange involves the OD− ion and the cation and neutral forms of the compound.