Which of the following is the strongest base ?

Options

A. tert-butoxide
B. Ethoxide
C. iso-propoxide
D. Methoxide

Answer

To determine which of the following compounds is the strongest base among tertiary butoxide, ethoxide, isopropoxide, and methoxide, we can analyze their structures and the effects of their substituents on basicity.

### Step-by-Step Solution:

1. **Understanding Basicity**:
- Basicity refers to the ability of a compound to donate a lone pair of electrons or accept protons. The stronger the base, the higher its tendency to donate its lone pair.

2. **Analyzing the Options**:
- **Option 1: Tertiary Butoxide (C(CH3)3O-)**:
- This compound has three methyl (CH3) groups attached to the central carbon. The presence of these three electron-donating groups enhances the electron density on the oxygen atom, increasing its ability to donate electrons and accept protons.

- **Option 2: Ethoxide (CH3CH2O-)**:
- Ethoxide has two carbon atoms and one methyl group. While it also exhibits a +I effect (inductive effect) due to the alkyl group, the effect is weaker compared to tertiary butoxide because it has fewer electron-donating groups.

- **Option 3: Isopropoxide ((CH3)2CHO-)**:
- Isopropoxide has two methyl groups and one ethyl group. The +I effect is present, but again, it is less than that of tertiary butoxide due to having only two methyl groups.

- **Option 4: Methoxide (CH3O-)**:
- Methoxide has only one methyl group. While it does have a +I effect, it is the weakest among the four options due to the least number of electron-donating groups.

3. **Comparing Basicity**:
- The strength of the base is influenced by the number of electron-donating alkyl groups. The more alkyl groups present, the higher the electron density on the oxygen, and thus, the stronger the base.
- Tertiary butoxide has the highest number of electron-donating groups (three methyl groups), followed by isopropoxide (two methyl groups), ethoxide (one methyl group), and methoxide (one methyl group).

4. **Conclusion**:
- Based on the analysis, tertiary butoxide has the highest basicity due to the strong +I effect from three methyl groups, making it the strongest base among the options provided.

### Final Answer:
The strongest base among the given options is **Tertiary Butoxide (Option 1)**.

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