For making `(CH_3)_3C-O-C_2H_5` the ideal combination is -

Options

A. `(CH_3)_3 CONa and C_2H_5Br`
B. `(CH_3)_3 CBr and C_2H_5ONa`
C. Both the above
D. None

Answer

To determine the ideal combination for synthesizing the compound `(CH₃)₃C-O-C₂H₅`, we need to analyze the two given options based on the reaction mechanism involved, which is likely an SN2 reaction. Here’s a step-by-step solution:

### Step 1: Identify the structure of the target compound
The target compound `(CH₃)₃C-O-C₂H₅` consists of a tert-butyl group `(CH₃)₃C-` attached to an ethoxy group `-O-C₂H₅`.

### Step 2: Understand the SN2 reaction mechanism
In an SN2 reaction, a nucleophile attacks an electrophilic carbon atom, resulting in the displacement of a leaving group. The ideal scenario for an SN2 reaction is to have a primary or secondary carbon as the electrophile because steric hindrance can hinder the nucleophile's approach.

### Step 3: Analyze the first option
Let’s denote the first option as:
- Nucleophile: `CH₃₃C-O⁻` (tert-butoxide)
- Electrophile: `C₂H₅-Br` (ethyl bromide)

In this case, the nucleophile (tert-butoxide) is attacking the primary carbon of ethyl bromide. Since the carbon is primary, the steric hindrance is minimal, allowing for a successful nucleophilic attack.

### Step 4: Analyze the second option
Let’s denote the second option as:
- Nucleophile: `CH₃₃C-O⁻` (tert-butoxide)
- Electrophile: `C(CH₃)₃-Br` (tert-butyl bromide)

Here, the nucleophile is attempting to attack a tertiary carbon (from tert-butyl bromide). Tertiary carbons are highly hindered due to the presence of three bulky alkyl groups, which makes it difficult for the nucleophile to approach and effectively perform the attack.

### Step 5: Conclusion
Based on the analysis:
- The first option allows for an effective SN2 reaction due to the primary carbon being attacked.
- The second option is not effective due to steric hindrance at the tertiary carbon.

Thus, the ideal combination for making `(CH₃)₃C-O-C₂H₅` is **Option A**.