In the preparation of alkene from alcohol using `Al_(2)O_(3)`, which is effective factor?

Options

A. Porousity of `Al_2O_3`
B. Temperature
C. Concentration
D. Surface area of `Al_2O_3`

Answer

To solve the question regarding the effective factor in the preparation of alkene from alcohol using `Al2O3`, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When alcohol is heated in the presence of `Al2O3`, it undergoes dehydration to form an alkene. The general reaction can be represented as:
\[ \text{RCH}_2\text{CH}_2\text{OH} \xrightarrow{\text{Al}_2\text{O}_3, \text{Heat}} \text{RCH}=\text{CH}_2 + \text{H}_2\text{O} \]

2. **Identifying the Conditions**:
- The reaction is sensitive to the temperature at which it is conducted. The effective temperature range for this dehydration reaction to yield alkenes is typically between 350 to 380 degrees Celsius.

3. **Exploring Different Temperatures**:
- If the temperature is lower (e.g., 220 to 250 degrees Celsius), the reaction does not yield alkenes but instead forms ethers:
\[ 2 \text{RCH}_2\text{CH}_2\text{OH} \xrightarrow{\text{Al}_2\text{O}_3, \text{Heat}} \text{RCH}_2\text{CH}_2\text{OCH}_2\text{CH}_2\text{R} + \text{H}_2\text{O} \]

4. **Conclusion on Effective Factor**:
- Since the product of the reaction (alkene vs ether) depends significantly on the temperature, we conclude that temperature is the most critical factor in determining the outcome of the reaction when preparing alkenes from alcohol using `Al2O3`.

5. **Final Answer**:
- The effective factor in the preparation of alkene from alcohol using `Al2O3` is **B) Temperature**.