Which of the following statements are correct about nucleophilic acyl substitution ?

Options

A. `RCOCl` is more reactive than `RCON_3` (acid azide).
B. `RCON_3` is more reactive then enhydride.
C. `RCON_3` is less reactive than anhydride.
D. Esters are less reactive than anhydrides but more reactive tham amides.

Answer

To determine which statements are correct about nucleophilic acyl substitution, we will analyze each statement based on the reactivity of different acyl compounds.

### Step-by-Step Solution:

1. **Understanding Nucleophilic Acyl Substitution**:
Nucleophilic acyl substitution is a reaction where a nucleophile attacks the carbonyl carbon of an acyl compound, leading to the substitution of a leaving group. The reactivity of the acyl compound is influenced by the nature of the leaving group.

2. **Reactivity Order of Acyl Compounds**:
The general reactivity order of acyl compounds in nucleophilic acyl substitution is:
- Acid chlorides (RCOCl)
- Acid anhydrides (RCO-O-COR')
- Acid azides (RCON3)
- Carboxylic acids (RCOOH)
- Esters (RCOOR')
- Amides (RCONR2)

3. **Evaluating the Statements**:
- **Statement A**: "RCOCl (acid chlorides) are more reactive than acid azides."
- **Evaluation**: This is true. Acid chlorides are indeed more reactive than acid azides.
- **Statement B**: "Acid azides are more reactive than anhydrides."
- **Evaluation**: This is also true. Acid azides are more reactive than acid anhydrides.
- **Statement C**: "Acid azides are less reactive than anhydrides."
- **Evaluation**: This is false. As established, acid azides are more reactive than anhydrides.
- **Statement D**: "Esters are less reactive than anhydrides."
- **Evaluation**: This is true. Esters are indeed less reactive than anhydrides.

4. **Conclusion**:
The correct statements about nucleophilic acyl substitution are A, B, and D. Therefore, the final answer is:
- **Correct Statements**: A, B, D.