Among the following compounds ,the strongest base is

Options

A. `NH_2-overset(O)overset(||)C-NH_2`
B. `NH_2-overset(NH)overset(||)C-NH_2`
C. `C_6H_5-NH_2`
D. `CH_3-NH-CH_3`

Answer

To determine which compound is the strongest base among the given options, we can follow these steps:

### Step 1: Identify the types of amines
- Alkyl amines and aryl amines are the two types of amines we will consider.
- Alkyl amines (like methylamine) are generally stronger bases than aryl amines (like aniline) because the alkyl groups are electron-donating, which increases the electron density on the nitrogen atom.

**Hint:** Remember that alkyl groups are electron-donating while aryl groups can withdraw electron density due to resonance.

### Step 2: Compare the basicity of alkyl and aryl amines
- In aryl amines, the lone pair of electrons on the nitrogen is delocalized into the aromatic ring, making it less available for protonation.
- In contrast, the lone pair in alkyl amines is more available for donation due to the electron-donating nature of the alkyl groups.

**Hint:** Consider the effect of resonance in aryl amines that stabilizes the lone pair, making it less basic.

### Step 3: Analyze specific compounds
- Among the compounds given, we have urea and guanidine.
- Guanidine has a structure that allows for resonance stabilization of the lone pairs on nitrogen. It has multiple resonance forms that enhance its basicity.

**Hint:** Look for structures that allow for resonance stabilization; they often indicate stronger bases.

### Step 4: Compare urea and guanidine
- Urea has a carbonyl group that can withdraw electron density from the nitrogen, making it less basic than guanidine.
- Guanidine, on the other hand, can stabilize the positive charge that results from protonation through resonance, making it a stronger base.

**Hint:** Identify electron-withdrawing and electron-donating groups in the structures; this will help you determine which compound is more basic.

### Step 5: Conclusion
- Based on the analysis, guanidine is the strongest base among the given compounds due to its ability to stabilize the lone pair on nitrogen through resonance and its overall electron-donating character.

**Final Answer:** The strongest base among the given compounds is **guanidine**.