The main product of the following reaction is `C_6H_5CH_2CH(OH)CH(CH_3)_2 overset("conc". H_2SO_4)to ?`

Options

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Answer

To solve the problem, we need to analyze the reaction of the compound \( C_6H_5CH_2CH(OH)CH(CH_3)_2 \) with concentrated sulfuric acid (\( H_2SO_4 \)). The steps are as follows:

### Step 1: Protonation of the Alcohol
When the compound is treated with concentrated sulfuric acid, the first step is the protonation of the hydroxyl group (-OH) by the acid. This converts the -OH group into a better leaving group, forming a positively charged oxonium ion.

**Hint:** Remember that acids donate protons (H⁺) to increase the electrophilicity of the alcohol.

### Step 2: Formation of Carbocation
After protonation, the oxonium ion loses a water molecule (H₂O), resulting in the formation of a carbocation. The carbocation is formed at the carbon that was originally attached to the -OH group.

**Hint:** Identify the position of the carbocation and consider its stability based on the surrounding groups.

### Step 3: Carbocation Rearrangement
Next, we check if the carbocation can rearrange to form a more stable carbocation. In this case, a hydride shift can occur from the adjacent carbon, leading to a more stable benzylic carbocation.

**Hint:** Look for possible shifts that can stabilize the carbocation, such as hydride or alkyl shifts.

### Step 4: Elimination to Form Alkene
The final step involves elimination, where a proton is removed from the adjacent carbon to the carbocation, resulting in the formation of a double bond (alkene). The product will be an alkene with a double bond between the carbons that were involved in the carbocation formation.

**Hint:** Remember that the elimination reaction will yield an alkene, and consider the stereochemistry of the product.

### Step 5: Determine the Major Product
In this case, the major product will be a trans-alkene due to the stability of the trans configuration over the cis configuration. The trans product minimizes steric hindrance and is therefore more stable.

**Hint:** Compare the stability of cis and trans isomers to determine which is the major product.

### Final Product
The main product of the reaction is the trans-alkene, which can be represented as:

\[ C_6H_5CH=CHCH(CH_3)_2 \]

This is the final product after the reaction with concentrated sulfuric acid.

### Summary of Steps:
1. Protonation of -OH group.
2. Formation of carbocation.
3. Rearrangement to a more stable carbocation.
4. Elimination to form alkene.
5. Determine the major product based on stability (trans over cis).