Order of nucteophilicity is

Options

A. `CH_(3)O^(-)lt C_(2) H_(5) O^(-)`
B. `C_(2) H_(5) O^(-) lt C_(2) H_(5) S^(-)`
C. `CH_(3) O^(-) lt CH_(3) S^(-)`
D. All of these

Answer

To determine the order of nucleophilicity, we will analyze the factors that influence nucleophilicity, including the presence of negative charge, the stability of that charge, and the inductive effects of substituents on the nucleophiles.

### Step-by-Step Solution:

1. **Understanding Nucleophilicity**:
- Nucleophilicity refers to the ability of a species to donate an electron pair to an electrophile. A stronger nucleophile is one that can donate its electrons more readily.

2. **Role of Charge**:
- The presence of a negative charge typically increases nucleophilicity. The more negative charge a nucleophile has, the better it can donate electrons.

3. **Inductive Effect**:
- The inductive effect (I effect) from alkyl groups can influence nucleophilicity. Alkyl groups are electron-donating, which can increase the electron density on the nucleophile, making it more nucleophilic.
- Methyl groups have a weaker +I effect compared to ethyl groups. Therefore, a nucleophile with an ethyl group will generally be more nucleophilic than one with a methyl group due to the stronger electron-donating ability of the ethyl group.

4. **Comparing Nucleophiles**:
- When comparing nucleophiles that differ only in the alkyl groups attached, we can conclude that the nucleophile with the larger alkyl group (like ethyl) will be more nucleophilic than one with a smaller alkyl group (like methyl).

5. **Comparison of Oxygen and Sulfur Nucleophiles**:
- When comparing nucleophiles that have negative charges on oxygen and sulfur, we must consider the size of the atoms. Sulfur is larger than oxygen, which means that the negative charge on sulfur is more stable due to its larger atomic radius.
- Therefore, a nucleophile with a negative charge on sulfur will be more nucleophilic than one with a negative charge on oxygen.

6. **Final Order of Nucleophilicity**:
- Based on the above factors, we can conclude that the order of nucleophilicity will depend on the nature of the substituents and the atom carrying the negative charge.
- The correct order of nucleophilicity can be summarized as follows:
- Nucleophiles with larger alkyl groups (like ethyl) > Nucleophiles with smaller alkyl groups (like methyl) > Nucleophiles with negative charge on sulfur > Nucleophiles with negative charge on oxygen.

7. **Conclusion**:
- Thus, the overall order of nucleophilicity is determined by both the charge and the stability of that charge, influenced by the inductive effects of substituents.