Which of the following types of alcohol contain a bond between `sp^2` hybridised carbon and OH group ?

Options

A. Primary allylic alcohols
B. Secondary allylic alcohols
C. Tertiary allylic alcohols
D. vinylic alcohols

Answer

To determine which types of alcohol contain a bond between an sp² hybridized carbon and an OH group, we need to understand the structure of different types of alcohols and the hybridization of their carbon atoms.

### Step-by-Step Solution:

1. **Identify Alcohol Types**:
- Alcohols can be classified into three categories based on the carbon atom to which the hydroxyl (OH) group is attached: primary (1°), secondary (2°), and tertiary (3°) alcohols.

2. **Understanding Hybridization**:
- Carbon atoms can be hybridized in different ways:
- **sp³ hybridization**: This occurs when a carbon atom is bonded to four other atoms (single bonds).
- **sp² hybridization**: This occurs when a carbon atom is bonded to three other atoms (one double bond and two single bonds).

3. **Allylic Alcohols**:
- Allylic alcohols are a specific type of alcohol where the hydroxyl group is attached to a carbon atom that is adjacent to a carbon-carbon double bond (C=C). The carbon atom in the allylic position is sp² hybridized.

4. **Determine the Bond**:
- In allylic alcohols, the carbon that is bonded to the hydroxyl group (OH) is sp² hybridized because it is part of a system that includes a double bond.

5. **Conclusion**:
- Therefore, the type of alcohol that contains a bond between an sp² hybridized carbon and an OH group is **allylic alcohol**.