The order of leaving group ability is
`.^(-)underset((I))(OAc).^(-) underset((II))(OMe).^(-)underset((III))(SO_3Me).^(-)underset((IV))(SO_3CF_3)` The order of leaving group ability is

Options

A. `I gt II gt III gt IV`
B. `IV gt III gt II gt I`
C. `I gt III gt IV gt II`
D. `IV gt III gt I gt II`

Answer

To determine the order of leaving group ability among the given groups, we need to analyze their basicity and the influence of their substituents. The ability of a leaving group is generally inversely related to its basicity; weaker bases are better leaving groups.

### Step-by-Step Solution:

1. **Identify the Leaving Groups**:
The leaving groups provided are:
- (I) OAc (Acetate)
- (II) OMe (Methoxy)
- (III) SO3Me (Methanesulfonate)
- (IV) SO3CF3 (Trifluoromethanesulfonate)

2. **Assess Basicity**:
- **OAc (Acetate)**: The acetate ion is a weak base due to the resonance stabilization of the negative charge by the carbonyl group (C=O).
- **OMe (Methoxy)**: The methoxy group is a stronger base compared to acetate because the methyl group is an electron-donating group, which destabilizes the negative charge.
- **SO3Me (Methanesulfonate)**: This group is a weak base due to the resonance stabilization of the sulfonate ion. It is a better leaving group than OAc.
- **SO3CF3 (Trifluoromethanesulfonate)**: This is the weakest base among the groups due to the strong electron-withdrawing effects of the trifluoromethyl group, making it an excellent leaving group.

3. **Rank the Leaving Groups**:
Based on the analysis of basicity:
- **SO3CF3** (weakest base, best leaving group)
- **SO3Me** (weak base, good leaving group)
- **OAc** (moderate base, fair leaving group)
- **OMe** (strongest base, poorest leaving group)

4. **Final Order of Leaving Group Ability**:
The order from best to worst leaving group is:
- SO3CF3 > SO3Me > OAc > OMe

### Conclusion:
The correct order of leaving group ability is:
**SO3CF3 > SO3Me > OAc > OMe**