Which will most readily precipitate with `AgNO_(3)` ?

Options

A. `H_(3)C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-Br`
B. `D_(3)C-underset(CD_(3))underset(|)overset(CD_(3))overset(|)(C)-Cl`
C. `H_(3)C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-Cl`
D. `H_(3)C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-l`

Answer

To determine which compound will most readily precipitate with AgNO₃, we need to analyze the stability of the leaving groups and the carbocation formed during the reaction. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
We have four compounds to consider:
1. CH₃-CH₂-Br (Bromopropane)
2. CH₃-CH₂-Cl (Chloropropane)
3. CH₃-CH₂-I (Iodopropane)
4. CH₃-CH(CH₃)-I (Iodopropane with a methyl group)

### Step 2: Understand the Reaction Mechanism
When a compound reacts with AgNO₃, the halogen (leaving group) will depart, forming a carbocation. The stability of this carbocation is crucial for the reaction to proceed efficiently. The leaving group ability also plays a significant role in determining which compound will precipitate the fastest.

### Step 3: Analyze the Leaving Groups
The leaving groups in our compounds are:
- Bromine (Br)
- Chlorine (Cl)
- Iodine (I)

Among these, the order of leaving group ability is:
- Iodine (I⁻) > Bromine (Br⁻) > Chlorine (Cl⁻)

Iodine is the best leaving group due to its larger size, which allows it to stabilize the negative charge better when it leaves.

### Step 4: Determine the Stability of the Carbocations
The stability of the carbocation formed after the leaving group departs is also important. More substituted carbocations are generally more stable:
- Primary carbocation (less stable)
- Secondary carbocation (more stable)
- Tertiary carbocation (most stable)

In our case:
- CH₃-CH₂-Br forms a primary carbocation.
- CH₃-CH₂-Cl also forms a primary carbocation.
- CH₃-CH₂-I forms a primary carbocation.
- CH₃-CH(CH₃)-I forms a secondary carbocation, which is more stable.

### Step 5: Conclusion
Since Iodine is the best leaving group and the compound CH₃-CH(CH₃)-I forms a more stable secondary carbocation, it will react the fastest with AgNO₃ and precipitate the most readily.

### Final Answer
**The compound that will most readily precipitate with AgNO₃ is CH₃-CH(CH₃)-I.**

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