Hypohalous Acids
The most common hypohalous acids, HOCl and HOBr, are relatively weak acids (pKa = 7.5 & 8.6 respectively) that are only stable in solution. These acids and their ester derivatives are formed reversibly when the corresponding halogens are dissolved in hydroxylic solvents.
| X2 + H2O |
|
HOX + HX |
|---|---|---|
| X2 + ROH |
|
ROX + HX |
For a solution of chlorine in water the equilibrium constant is only about 5 * 10-4. The concentration of HOCl may be increased by adding silver oxide ( Ag(+) reduces the chloride ion concentration and the oxide increases the pH ), but this is not a common procedure. As a rule, these reagents are prepared by hydrolysis of N-chloro and N-bromo precursors immediately prior to their use.
