Rank the following in order of increasing leaving group ability, putting the worst leaving group first. $$\begin{array} { c c c c }
\mathrm { H } _ { 2 } \mathrm { O } & \mathrm { HO } ^ { - } & \mathrm { NH } _ { 3 } & \mathrm { H } _ { 2 } \mathrm {~N} ^ { - } \
\text {I } & \text { II } & \text { III } & \text { IV }
\end{array}$$

Question

Rank the following in order of increasing leaving group ability, putting the worst leaving group first. $$\begin{array} { c c c c } 
\mathrm { H } _ { 2 } \mathrm { O } & \mathrm { HO } ^ { - } & \mathrm { NH } _ { 3 } & \mathrm { H } _ { 2 } \mathrm {~N} ^ { - } \
\text {I } & \text { II } & \text { III } & \text { IV }
\end{array}$$

Quizplus · Accepted Answer

The correct order of increasing leaving group ability is: $$\mathrm { H } _ { 2 } \mathrm { O } < \mathrm { NH } _ { 3 } < \mathrm { HO } ^ { - } < \mathrm { H } _ { 2 } \mathrm {~N} ^ { - }$$This is because the leaving group ability of a group increases with its stability. The more stable the group, the more likely it is to leave the molecule. Water is a very stable molecule, so it is a poor leaving group. Ammonia is less stable than water, so it is a better leaving group. Hydroxide ion is even less stable than ammonia, so it is a better leaving group still. Hydrazide ion is the least stable of the four groups, so it is the best leaving group.

Rank the Following in Order of Increasing Leaving Group Ability