In _________ alcohols , the -OH group is attached to a `sp^2` hybridised carbon atom.

Options

A. allylic
B. benzylic
C. vinylic
D. all of these

Answer

To solve the question, "In _________ alcohols, the -OH group is attached to a `sp^2` hybridised carbon atom," we need to identify the type of alcohol where the hydroxyl (-OH) group is bonded to a carbon atom that is `sp^2` hybridized.

### Step-by-Step Solution:

1. **Understanding Hybridization**:
- The hybridization of a carbon atom can be determined by its steric number, which is the sum of the number of sigma bonds and lone pairs around the carbon atom.
- For `sp^2` hybridization, the steric number is 3. This means the carbon atom is bonded to three other atoms (which can include other carbons or hydrogens) and has no lone pairs.

2. **Identifying Alcohol Types**:
- We need to consider different types of alcohols and their structures to see which one has the -OH group attached to an `sp^2` hybridized carbon.

3. **Types of Alcohols**:
- **Allylic Alcohol**: The -OH group is attached to a carbon that is adjacent to a carbon-carbon double bond. The carbon with the -OH group is `sp^2` hybridized.
- **Benzylic Alcohol**: The -OH group is attached to a carbon that is adjacent to a benzene ring. The carbon with the -OH group is also `sp^2` hybridized.
- **Vinylic Alcohol**: The -OH group is attached to a carbon that is part of a double bond. The carbon with the -OH group is `sp^2` hybridized.

4. **Conclusion**:
- Among the options, both allylic and benzylic alcohols have the -OH group attached to an `sp^2` hybridized carbon atom. However, the question specifically asks for one type of alcohol.
- The correct answer is **benzylic alcohol**, as it is a common example where the -OH group is attached to a carbon adjacent to a benzene ring, which is `sp^2` hybridized.

### Final Answer:
In **benzylic** alcohols, the -OH group is attached to a `sp^2` hybridised carbon atom.

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