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 need to identify the initiation step and the mechanism involved in this reaction.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The dehydration of alcohol involves the removal of a water molecule (H₂O) from the alcohol to form an alkene. This process is typically facilitated by heating the alcohol with a strong acid, such as concentrated H₂SO₄.

2. **Initiation Step**:
- The first step in the dehydration process is the **protonation of the alcohol**. When the alcohol (R-OH) is mixed with concentrated H₂SO₄, the acid donates a proton (H⁺) to the alcohol.
- This step can be represented as:
\[ R-OH + H^+ \rightarrow R-OH_2^+ \]
- Here, the alcohol molecule gains a proton, resulting in the formation of an oxonium ion (R-OH₂⁺).

3. **Mechanism**:
- Following the initiation step, the mechanism of dehydration proceeds through a **carbocation mechanism**.
- The protonated alcohol (oxonium ion) is now more reactive, and the bond between the oxygen and the carbon atom can break, leading to the formation of a carbocation (R⁺) and the release of a water molecule (H₂O).
- This can be represented as:
\[ R-OH_2^+ \rightarrow R^+ + H_2O \]
- The carbocation can then lose a proton (deprotonation) to form the alkene (R=R').

4. **Final Answer**:
- Therefore, the initiation step is **protonation of alcohol**, and the mechanism that follows is a **carbocation mechanism**.

### Summary:
- **Initiation Step**: Protonation of alcohol
- **Mechanism**: Carbocation mechanism