Which of the following is the strongest base in water?

Options

A.
B.
C.
D.

Answer

To determine which of the following compounds is the strongest base in water, we need to analyze the stability of their conjugate acids. The stronger the base, the less stable its conjugate acid will be. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
Assume we have four compounds to analyze:
1. Compound A (e.g., NH2-)
2. Compound B (e.g., C6H5NH2)
3. Compound C (e.g., R-NH-)
4. Compound D (e.g., R2N-)

### Step 2: Formulate the Conjugate Acids
To analyze the basicity, we need to add a proton (H⁺) to each compound to form their conjugate acids:
- For Compound A: NH2- + H⁺ → NH3 (conjugate acid)
- For Compound B: C6H5NH2 + H⁺ → C6H5NH3⁺ (conjugate acid)
- For Compound C: R-NH- + H⁺ → R-NH2 (conjugate acid)
- For Compound D: R2N- + H⁺ → R2NH (conjugate acid)

### Step 3: Analyze the Stability of Conjugate Acids
Next, we need to evaluate the stability of each conjugate acid formed:
- **Compound A (NH3)**: Stable, as it has no electron-withdrawing groups.
- **Compound B (C6H5NH3⁺)**: Less stable due to the presence of the aromatic ring, which can withdraw electron density.
- **Compound C (R-NH2)**: Generally stable, but depends on R group.
- **Compound D (R2NH)**: Likely stable, especially if R groups are electron-donating.

### Step 4: Compare Basicity
The stability of the conjugate acids indicates the strength of the bases:
- The less stable the conjugate acid, the stronger the base.
- Compound A (NH3) is stable, but not as strong as others.
- Compound B (C6H5NH3⁺) is less stable due to electron withdrawal.
- Compound C (R-NH2) can be a strong base depending on R.
- Compound D (R2NH) is likely the strongest base due to electron-donating R groups enhancing basicity.

### Step 5: Conclusion
Based on the analysis, Compound D (R2NH) is the strongest base in water because it can donate electrons more readily, leading to a less stable conjugate acid.

### Final Answer:
**The strongest base in water is Compound D (R2NH).**

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