Which of the followig is the strongest base ?

Options

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

Answer

To determine which of the given compounds is the strongest base, we will analyze the electron-donating capacity of each compound. The stronger the electron-donating ability, the stronger the base.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we are considering are:
- Tertiary butoxide (t-butoxide)
- Ethoxide
- Isopropoxide
- Methoxide

2. **Understand the Structure of Each Compound**:
- **Tertiary Butoxide (t-butoxide)**: This has the structure (CH3)3CO⁻. It has three methyl groups attached to the central carbon, which can donate electrons.
- **Ethoxide**: This has the structure CH3CH2O⁻. It has one ethyl group (CH2CH3) attached to the oxygen.
- **Isopropoxide**: This has the structure (CH3)2CHO⁻. It has two methyl groups and one hydrogen attached to the central carbon.
- **Methoxide**: This has the structure CH3O⁻. It has one methyl group attached to the oxygen.

3. **Analyze the Electron Donating Capacity**:
- The base strength is influenced by the inductive effect of the alkyl groups attached to the oxygen atom. Alkyl groups are electron-donating due to their +I (inductive) effect.
- Tertiary butoxide has three methyl groups, which provide a strong +I effect.
- Ethoxide has one ethyl group, which is less effective than three methyl groups.
- Isopropoxide has two methyl groups, which is stronger than ethoxide but weaker than tertiary butoxide.
- Methoxide has only one methyl group, making it the weakest among these options.

4. **Compare the Strengths**:
- Tertiary butoxide (t-butoxide) > Isopropoxide > Ethoxide > Methoxide
- Therefore, tertiary butoxide has the highest electron-donating capacity and is the strongest base among the four.

5. **Conclusion**: The strongest base among the given compounds is **Tertiary Butoxide (t-butoxide)**.