Chapter 11.7, Problem 11.10PSP

The Raschig reaction produces the industrially important reducing agent hydrazine, N₂H₄, from ammonia, NH₃, and hypochlorite ion, OCl⁻, in basic aqueous solution. A proposed mechanism is

Step 1: ${\text{NH}}_3(\text{aq})+{\text{OCl}}^{-}(\text{aq})\stackrel{\text{slow}}{\to }{\text{NH}}_2\text{Cl}(\text{aq})+{\text{OH}}^{-}(\text{aq})$

Step 2: ${\text{NH}}_2\text{Cl}(\text{aq})+{\text{NH}}_3(\text{aq})\stackrel{\text{fast}}{\to }{\text{N}}_2{\text{H}}_5^{+}(\text{aq})+{\text{Cl}}^{-}(\text{aq})$

Step 3: ${\text{N}}_2{\text{H}}_5^{+}(\text{aq})+{\text{OH}}^{-}(\text{aq})\stackrel{\text{fast}}{\to }{\text{N}}_2{\text{H}}_4(\text{aq})+{\text{H}}_2\text{O}(\ell )$

1. (a) What is the overall stoichiometric equation?
2. (b) Which step is rate-limiting?
3. (c) What reaction intermediates are involved?
4. (d) What rate law is predicted by this mechanism?