`CHF_(2) Br overset(OH^(-))(rarr) (A)` [Intermediate] `overset("Trans -2-butene")(rarr) (B)`

Options

A.
B.
C.
D.

Answer

To solve the question regarding the reaction of CHF₂Br with OH⁻ and then with trans-2-butene, we will break down the process step by step.

### Step 1: Reaction of CHF₂Br with OH⁻
The first step involves the reaction of CHF₂Br with a hydroxide ion (OH⁻). The hydroxide ion acts as a base and abstracts a proton (H⁺) from the CHF₂Br molecule.

**Chemical Equation:**
\[ \text{CHF}_2\text{Br} + \text{OH}^- \rightarrow \text{CF}_2\text{Br}^- + \text{H}_2\text{O} \]

### Step 2: Formation of Carbene
After the proton abstraction, we have CF₂Br⁻. The bromine (Br) atom is a good leaving group and will leave, resulting in the formation of a carbene intermediate, specifically a singlet carbene (CF₂).

**Chemical Equation:**
\[ \text{CF}_2\text{Br}^- \rightarrow \text{CF}_2 + \text{Br}^- \]

### Step 3: Reaction with Trans-2-butene
Now, the singlet carbene (CF₂) will react with trans-2-butene. The double bond in trans-2-butene can react with the carbene. The carbene will insert itself into the double bond of trans-2-butene.

**Chemical Structure of Trans-2-butene:**
\[ \text{CH}_3\text{CH}=\text{CH}\text{CH}_3 \]

### Step 4: Insertion of the Carbene
When the carbene (CF₂) inserts into the double bond of trans-2-butene, it will form a new carbon-carbon bond. The stereochemistry of the double bond will remain unchanged because the insertion does not lead to a change in the relative positions of the substituents.

**Resulting Product Structure:**
The resulting product will have the two fluorine atoms attached to one of the carbon atoms that were involved in the double bond of trans-2-butene.

### Final Product
The final product can be represented as follows:
\[ \text{CH}_3\text{C}(\text{F}_2)\text{C}(\text{H})\text{CH}_3 \]

### Summary of the Reaction
The overall reaction can be summarized as:
1. CHF₂Br reacts with OH⁻ to form CF₂Br⁻.
2. CF₂Br⁻ loses Br⁻ to form the singlet carbene CF₂.
3. CF₂ reacts with trans-2-butene to form the final product.