Dehyration of alcohol to alkene by heating with conc. `H_(2)SO_(4)`, the initiation step is _______ followed with ________ mechanism.

Options

A. Elimination of water, free radical
B. Formation of an ester, free radical
C. Protonation of alcohol, carbocation
D. Protonation of alcohol, carbanion

Answer

To solve the question regarding the dehydration of alcohol to alkene by heating with concentrated sulfuric acid (H₂SO₄), we can break down the process into clear steps:

### Step-by-Step Solution:

1. **Identify the Reaction**: The reaction involves the dehydration of an alcohol, which means the removal of a water molecule to form an alkene.

2. **Initiation Step**: The first step in this reaction is the **protonation of the alcohol**. When the alcohol (R-OH) is treated with concentrated H₂SO₄, the hydroxyl group (-OH) of the alcohol gets protonated. This results in the formation of an oxonium ion (R-OH₂⁺).

- **Chemical Equation**:
\[ R-OH + H_2SO_4 \rightarrow R-OH_2^+ + HSO_4^- \]

3. **Formation of Carbocation**: After protonation, the next step involves the **removal of a water molecule** from the oxonium ion. This leads to the formation of a carbocation (R⁺).

- **Chemical Equation**:
\[ R-OH_2^+ \rightarrow R^+ + H_2O \]

4. **Deprotonation to Form Alkene**: The final step involves the **deprotonation** of the carbocation. A hydrogen ion (H⁺) is removed from an adjacent carbon, resulting in the formation of a double bond, thus yielding the alkene.

- **Chemical Equation**:
\[ R^+ \rightarrow R=CH_2 + H^+ \]

5. **Mechanism**: The mechanism that describes this reaction is the **E1 mechanism** (unimolecular elimination). This is characterized by the formation of a carbocation intermediate, which is a key feature of E1 reactions.

### Final Answer:
- The initiation step is **protonation of alcohol**, followed with **E1 mechanism**.