Choose an allylic alcohol form the given options.

Options

A. `CH_2=CH-CH_2-OH`
B. `CH_2=CH-OH`
C.
D.

Answer

To determine which of the given options is an allylic alcohol, we need to understand the definitions and characteristics of allylic alcohols.

### Step-by-Step Solution:

1. **Understanding Alcohols**:
- Alcohols are organic compounds that contain one or more hydroxyl (–OH) groups attached to a carbon atom. The carbon atom to which the –OH group is attached is called the alcohol carbon.

**Hint**: Remember that the presence of the –OH group is what defines an alcohol.

2. **Defining Allylic Alcohol**:
- An allylic alcohol is a specific type of alcohol where the hydroxyl group (–OH) is attached to a carbon atom that is adjacent to a carbon-carbon double bond (C=C). This means that the carbon with the –OH group is sp³ hybridized and is next to a carbon that is part of a vinyl group (C=C).

**Hint**: Allylic alcohols have the –OH group on a carbon that is next to a double bond.

3. **Identifying Vinyl Group**:
- A vinyl group is defined as a carbon-carbon double bond (C=C) where one of the carbons is also attached to a hydrogen atom. The structure of a vinyl group can be represented as –CH=CH2.

**Hint**: Look for the presence of a double bond in the structure to identify vinyl groups.

4. **Analyzing the Options**:
- We need to evaluate each option provided to see which one fits the definition of allylic alcohol:
- **Option A**: If the structure is CH2=CH-CH2OH, the –OH group is on the carbon adjacent to the double bond, making this an allylic alcohol.
- **Option B**: If the structure is CH2=CH2OH, the –OH group is on a carbon that is part of the double bond itself, making this a vinylic alcohol, not allylic.
- **Option C**: If the structure has a carbon attached to a benzene ring with an –OH group, this is not an allylic alcohol as it does not have the required adjacent double bond.
- **Option D**: If the structure is a benzyl alcohol (where the –OH is attached to a carbon that is part of a benzene ring), this is also not an allylic alcohol.

**Hint**: Compare the structure of each option to the definition of allylic alcohol to make your determination.

5. **Conclusion**:
- After analyzing all the options, we find that **Option A** is the only structure that qualifies as an allylic alcohol because the –OH group is attached to a carbon that is adjacent to a carbon-carbon double bond.

**Final Answer**: **Option A is the correct allylic alcohol.**