To determine which of the given reactions are elimination reactions, we need to analyze each chemical transformation.
An elimination reaction typically involves the removal of atoms or groups from a molecule, resulting in the formation of a double bond or a multiple bond. Commonly, these reactions involve the production of small molecules such as water (H₂O) or hydrogen halides (HX).
Let's examine each reaction:
1. [tex]\(\text{CH}_3\text{OH} + \text{CH}_3\text{COOH} \rightarrow \text{CH}_3\text{CO}_2\text{CH}_3 + \text{H}_2\text{O}\)[/tex]:
- This reaction involves methanol ([tex]\(\text{CH}_3\text{OH}\)[/tex]) reacting with acetic acid ([tex]\(\text{CH}_3\text{COOH}\)[/tex]) to form methyl acetate ([tex]\(\text{CH}_3\text{CO}_2\text{CH}_3\)[/tex]) and water ([tex]\(\text{H}_2\text{O}\)[/tex]).
- This is a condensation reaction (specifically, esterification) where two molecules combine to form a larger molecule with the elimination of water. However, it's primarily classified as a substitution reaction where one group is substituted by another, leading to the formation of a new compound along with water.
- This is not an elimination reaction.
2. [tex]\(\text{C}_3\text{H}_7\text{OH} \rightarrow \text{C}_3\text{H}_6 + \text{H}_2\text{O}\)[/tex]:
- This reaction involves the dehydration of propanol ([tex]\(\text{C}_3\text{H}_7\text{OH}\)[/tex]) to form propene ([tex]\(\text{C}_3\text{H}_6\)[/tex]) and water ([tex]\(\text{H}_2\text{O}\)[/tex]).
- This fits the definition of an elimination reaction, where a molecule of water is removed from the alcohol, resulting in the formation of a double bond in the propene.
- This is an elimination reaction.
3. [tex]\(\text{H}_5\text{C}_2\text{Br} + \text{NaOH} \rightarrow \text{C}_2\text{H}_4 + \text{NaBr} + \text{H}_2\text{O}\)[/tex]:
- This reaction involves bromoethane ([tex]\(\text{H}_5\text{C}_2\text{Br}\)[/tex]) reacting with sodium hydroxide ([tex]\(\text{NaOH}\)[/tex]) to form ethene ([tex]\(\text{C}_2\text{H}_4\)[/tex]), sodium bromide ([tex]\(\text{NaBr}\)[/tex]), and water ([tex]\(\text{H}_2\text{O}\)[/tex]).
- Here, both hydrogen and bromine are eliminated from bromoethane to form ethene, without adding atoms from the base to the carbon chain.
- This is an elimination reaction.
Based on this analysis:
- The first reaction is not an elimination reaction.
- The second reaction is an elimination reaction.
- The third reaction is an elimination reaction.
Therefore, the correct identification is:
The second and third reactions are elimination reactions.
