The order of decreasing nucleophilicity of the following is

Options

A. `H_(2)O gt OH^(-) gt CH_(3)COO^(-) gt CH_(3)O^(-)`
B. `CH_(3)O^(-) gt OH^(-) gt CH_(3)COO^(-) gt H_(2)O`
C. `CH_(3)COO^(-) gt CH_(3)O^(-) gt H^(-) gt H_(2)O`
D. `HO^(-) gt CH_(3)O^(-) gt CH_(3)COO^(-) gt H_(2)O`

Answer

To determine the order of decreasing nucleophilicity among the given nucleophiles: H2O, OH-, CH3COO-, and CH3O-, we need to analyze the structure and electron availability of each nucleophile.

### Step-by-Step Solution:

1. **Identify the Nucleophiles**: The nucleophiles given are:
- H2O (water)
- OH- (hydroxide ion)
- CH3COO- (acetate ion)
- CH3O- (methoxide ion)

2. **Understand Nucleophilicity**: Nucleophilicity refers to the ability of a species to donate an electron pair to an electrophile. Generally, the more available the electron pair is, the stronger the nucleophile.

3. **Compare OH- and H2O**:
- **OH-** has a negative charge, which means it has an extra lone pair of electrons compared to H2O. This makes OH- a stronger nucleophile than H2O.
- **Conclusion**: OH- > H2O

4. **Analyze CH3O- (Methoxide Ion)**:
- CH3O- has a negative charge on the oxygen, similar to OH-. Additionally, the methyl group (CH3) is an electron-donating group due to its +I effect, which increases the electron density on the oxygen and makes the lone pair more available for nucleophilic attack.
- **Conclusion**: CH3O- > OH-

5. **Consider CH3COO- (Acetate Ion)**:
- In CH3COO-, the negative charge is delocalized between the two oxygen atoms due to resonance. This delocalization reduces the availability of the lone pair for nucleophilic attack, making it a weaker nucleophile compared to OH- and CH3O-.
- **Conclusion**: CH3COO- < OH- and CH3O-

6. **Final Comparison**:
- Based on the above analysis, we can summarize the nucleophilicity order as:
- CH3O- > OH- > H2O > CH3COO-

### Final Order of Decreasing Nucleophilicity:
**CH3O- > OH- > H2O > CH3COO-**