Melting points are normally highest for

Options

A. Tertiary amides
B. Secondary amides
C. Primary Amides
D. Amines.

Explanation

To solve the question regarding which category of compounds has the highest melting points, we will analyze the options provided: tertiary amides, secondary amides, primary amides, and amines.

### Step-by-Step Solution:

1. **Understanding Amides**:
- Amides are compounds that contain a carbonyl group (C=O) directly attached to a nitrogen atom (N). They can be classified into primary, secondary, and tertiary amides based on the number of carbon groups attached to the nitrogen.
- **Primary Amide**: Has one carbon group attached to the nitrogen (e.g., RCONH2).
- **Secondary Amide**: Has two carbon groups attached to the nitrogen (e.g., R1R2C=O-NH-R3).
- **Tertiary Amide**: Has three carbon groups attached to the nitrogen (e.g., R1R2R3C=O-N).

2. **Hydrogen Bonding in Amides**:
- Amides can exhibit intramolecular hydrogen bonding due to the presence of the carbonyl group and the amine group within the same molecule. This intramolecular hydrogen bonding is typically stronger than intermolecular hydrogen bonding but can lead to lower melting points because the molecules are less able to interact with each other.

3. **Understanding Amines**:
- Amines are compounds that contain one or more alkyl or aryl groups attached to a nitrogen atom. They can also form hydrogen bonds, but these are usually intermolecular hydrogen bonds.
- The presence of intermolecular hydrogen bonding in amines generally leads to higher melting points compared to amides.

4. **Comparison of Melting Points**:
- Since amides exhibit intramolecular hydrogen bonding, their melting points tend to be lower compared to amines which exhibit intermolecular hydrogen bonding.
- Among the options given, amines will have the highest melting points due to their ability to form strong intermolecular hydrogen bonds.

5. **Conclusion**:
- Based on the analysis, the category of compounds with the highest melting points is **amines**.

### Final Answer:
The melting points are normally highest for **amines**.