Step 1: Understanding the Question:
We need to classify "crotonyl alcohol" based on the position of its hydroxyl group relative to the carbon-carbon double bond.
Step 2: Detailed Explanation:
Crotonyl alcohol (also known as crotyl alcohol or 2-buten-1-ol) has the chemical formula:
\[ CH_3 - CH = CH - CH_2OH \]
1. In this structure, the $-OH$ group is attached to an $sp^3$ hybridized carbon atom.
2. This $sp^3$ carbon is directly adjacent to a carbon-carbon double bond ($C=C$).
3. Such alcohols, where the $-OH$ group is on the carbon next to a double bond, are classified as allylic alcohols.
Step 4: Final Answer:
Crotonyl alcohol is an allylic alcohol.